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Soil Microbial Community Responses to Dairy Manure or Ammonium Nitrate Applications
Abstract
Soil management practices that result in increased soil C also impact soil microbial biomass and community structure. In this study, the effects of dairy manure applications and inorganic N fertilizer on microbial biomass and microbial community composition were determined. Treatments examined were a control with no nutrient additions (CT), ammonium nitrate at 218 kg N ha−1 (AN), and manure N rates of 252 kg manure-N ha−1 (LM) and 504 kg manure-N ha−1 (HM). All plots were no-till cropped to silage corn (Zea mays, L. Merr) followed by a Crimson clover (Trifolium incarnatum, L.)/annual ryegrass (Lolium multiflorum, Lam.) winter cover crop. Treatments were applied yearly, with two-thirds of the N applied in late April or early May, and the remainder applied in September. Soil samples (0–5, 5–10, and 10–15 cm) were taken in March 1996, prior to the spring nutrient application. Polar lipid fatty acid (PLFA) analysis was used to assess changes in microbial biomass and community structure. Significantly greater soil C, N and microbial biomass in the 0–5 cm depth were observed under both manure treatments than in the CT and AN treatments. There was also a definable shift in the microbial community composition of the surface soils (0–5cm). Typical Gram-negative bacteria PLFA biomarkers were 15 and 27% higher in the LM and HM treatments than in the control. The AN treatment resulted in a 15% decrease in these PLFA compared with the control. Factor analysis of the polar lipid fatty acid profiles from all treatments revealed that the two manure amendments were correlated and could be described by a single factor comprised of typical Gram-negative bacterial biomarkers. The AN treatments from all three depths were also correlated and were described by a second factor comprised of typical Gram-positive bacterial biomarkers. These results demonstrate that soil management practices, such as manuring, that result in accumulations of organic carbon will result in increased microbial biomass and changes in community structure.
... (Fig I-4). This result was supported by some studies in paddy soil Tang et al., 2018) and other soil systems (Peacock et al., 2001;Denef et al., 2009;Wang et al., 2014). However, it contradicted other studies (Zhang et al., 2012b;Dong et al., 2014) and requires further investigations on the underlying mechanisms. ...
... For example, mineral N fertilizer increased the ratio of G+ to G− bacteria in forest soils after 120 days of incubation (Wang et al., 2014b). In two other studies, NPK fertilizer increased the relative abundance of G+ bacterial PLFAs in grasslands (Denef et al., 2009) and corn fields (Peacock et al., 2001). Thus, over the long term, G+ bacteria benefit the most from mineral fertilizer-derived nutrients in paddy soils. ...
... Straw replacement increased the abundance of G− bacteria in the 0−20 cm soil layer (Fig Ⅱ.3-1b, P > 0.05). This might be because G− bacteria preferentially utilize labile organic C in straw (Peacock et al., 2001). Unexpectedly, straw promoted the abundance of fungal PLFAs in the 10−20 cm soil layer ( Table Ⅱ.3-S1). ...
Rice feeds more than half of the world’s population; in addition, artificial rice paddies are an important contributor to global carbon emissions. Carbon turnover (production and oxidation) primarily comprises microbially mediated processes, and microorganisms (abundances and communities) are strongly affected by anthropogenic activities in paddy soils, such as fertilization and water management. In turn, microbial abundance and community shifts can strongly influence soil C turnover by affecting soil organic matter (SOM) decomposition through priming effects (PEs). This thesis aimed to gain a more comprehensive understanding of C turnover (CO2 and CH4) in paddy soils by determining the temporal dynamics of CO2 and CH4 and disentangling the underlying mechanisms. Uncertainty still exists about the contributions of the two main pathways (acetoclastic methanogenesis and hydrogenotrophic methanogenesis) to CH4 production throughout the rice growing season, especially under field conditions. To fill this knowledge gap, in Study 1 and 2, we took soil gas samples using passive diffusion gas samplers to determine the temporal dynamics of CO2 and CH4. Since labile C input affects microbial processes in soil, the C allocation from above- to belowground pools was quantified by 13CO2 pulse labelling of rice plants. Of particular interest was the result of the natural abundance 13C enrichment of CO2 over time under flooded conditions, indicating that hydrogenotrophic methanogenesis continuously contributed to CH4 production. Alternating wet-dry cycles (AWD) resulted in a significant decrease in CH4 concentrations, along with conspicuous isotopic signals indicative of CH4 oxidation. However, the time and magnitude of AWD should be carefully considered as it can reduce rice yield. Sulfate fertilizer had positive effects on rice plant biomass and grain yield, though it showed no effect on lowering CH4 concentrations. Especially under AWD conditions, sulfate fertilizer increased shoot biomass and stabilized grain production. Additionally, based on 13CO2 pulse labelling results, more than 50% of newly assimilated C was retained aboveground at grain-filling stage (14 days after pulse labelling), which is likely explained by a high C demand for fruit production. We did not detect any effect of sulfate addition and AWD on 13C allocation in the plant-soil system. In addition to these short-term effects of fertilizer addition, in Study 3, soil samples were collected from a long-term experimental trial and analyzed for microbial biomass and community composition. Both mineral and organic fertilization can prevent microbial biomass from decreasing vertically. In addition, Gram-positive (G+) bacteria benefited the most from mineral fertilizers, and the partial replacement of mineral fertilizer with manure primarily enhanced the abundance of G+ bacteria at 0−30 cm soil depth. In contrast, replacement with straw particularly enhanced the abundances of fungi at 10−20 cm soil depth, which is explained by the key role of fungi in straw decomposition. Study 4 was designed to investigate how the changes of microbial activity and communities, shown in Study 3, affect SOM decomposition through PE. 13C-glucose was added to incubated soils to mimic C input by rhizodeposition. Following glucose addition, SOM-derived microbial biomass C decreased at 0–10 cm in all soils (apparent PE). It was suggested that in upper soil depths with frequent C input through rhizodeposition and organic fertilizers, microorganisms focused on renewing their C rather than investing in growth after substrate addition. N mining mechanism suggests that primed CO2 is higher under nutrient-limited conditions as microorganisms produce extracellular enzymes to mine SOM for limiting nutrients. Our results fit well with this mechanism, as lower percentage primed CO2 (PECO2) was observed in soil with balanced nutrient conditions (NPK). In contrast, in low nutrient (unfertilized) or extra C (organic fertilized) conditions, PECO2 was higher because of the demand for nutrients. However, the higher positive primed-DOC together with weak PECO2 in topsoil than subsoil cannot be explained by N mining. Therefore, we proposed a mineral-related mechanism: glucose addition increased DOC by release of mineral-bound C biotically and/or abiotically. Apart from accelerating SOM decomposition, positive PECO2 can also be achieved by direct utilization of those released C. However, after 20 days of incubation, the organic C concentration was reduced by rebinding or co-precipitating to mineral surfaces, which can explain the negative PE at later incubation phases commonly observed in paddy soils. In summary, this thesis extends our understanding of plant-microbe interactions on CO2 and CH4 turnover in paddy soils. In addition, we drew attention to complex mechanisms of C turnover in submerged paddy soils: 1) apparent PE, 2) biotic and/or abiotic release of mineral-bound OC, 3) negative PE at later incubation phases. Considering the mineral-associated mechanisms (substrate desorption and resorption with soil matrix) in further investigations is crucial, as they alter substrate availability to microorganisms and thus affect soil C stocks. Moreover, the studied mechanisms are vital for maintaining food security and mitigating global warming through adaptations in management practices in rice cropping systems.
... Under a given cropping system, SOM content tended toward an equilibrium level, which was greater for clayey than for sandy soils. Application of organic amendments can improve the C and N content in the top 5 cm of the soil (Peacock et al., 2001), although the magnitude of the effect depends on their dry matter content. Consequently, effects can be small with liquid manure, such as that from pigs (Angers et al., 2010). ...
... A significant enhancement of the soil microbial biomass has frequently been reported following manure additions (e.g. Peacock et al., 2001). A recent meta-analysis has shown that activities of enzymes acquiring C, N, P, sulfur and energy were 1.3-3.3 ...
... In addition to increasing the total microbial population, manure applications can also change the community structure with a significant shift from Grampositive organisms in soil under crops given mineral fertilizer to one with many Gram-negative bacteria and more protozoa compared to mineral fertilizer applications or untreated controls (Peacock et al., 2001;Zhang et al., 2012). Likewise, the application of manure may enrich both r-and K-strategists when compared with an appropriate control soil (Parham et al., 2003). ...
This chapter reviews the impacts associated with the application of livestock and poultry manure on the ability of soil to deliver a range of ecosystem services that sustain plants, animals, people and the environment in which they live.
... Soil organic matter and C are important indicators of soil quality and influence many soil properties and processes. Cover crop grazing has the potential to improve organic matter through the aboveground and belowground CC biomass (Blanco-Canqui et al., 2015;Sokol et al., 2019;Gale and Cambardella, 2020;Xu et al., 2021) and cattle additions from manure (Drinkwater et al., 1998;Peacock et al., 2001;Russelle et al., 2007;Drewnoski et al., 2016;. Although organic matter is vital to soil health and soil ecosystem services, there is little research on CC grazing impacts on organic matter and C. As summarized in Table 2.3, while CC grazing generally does not reduce organic matter and C, there are some inconsistent findings on the impact of CC grazing on organic matter, soil C, and their fractions. ...
... The third study, located in Brazil, found that soil microbial biomass was greater in the CC grazed sites compared to the non-grazed sites (Table 2.4). Cattle manure is known to increase soil microbial biomass and activity in the soil (Frostegard et al., 1997;Peacock et al., 2001) and roots can contribute C to feed soil microorganisms (Hinsinger et al., 2009;Sokol et al., 2019;Gale and Cambardella, 2020). ...
... In a long term (6 yr) CC grazing study, Carvalho et al. (2010) argued that increasing stocking density reduces residue amount, although nutrient cycling, through manure additions, could counteract the potential negative effects of residue removal. It is well known that cattle manure can increase microbial biomass and activity in the soil (Fraser et al., 1988;Frostegard et al., 1997;Peacock et al., 2001) and contribute to soil fertility (Drinkwater et al., 1998;Russelle et al., 2007;Drewnoski et al., 2016). Also, moderate grazing density can improve soil microbial biomass whereas high density grazing can degrade microbial biomass (Souza et al., 2008;Carvalho et al., 2010). ...
Re-integrating crop and livestock production through cover crop (CC) and corn residue grazing could efficiently utilize resources and ensure profitability while improving environmental quality, but how this integration affects soils and crops is not well understood. We conducted two studies to address this. In the first study, we evaluated the impact of cattle (1.3-3.7 head ha-1) grazing an oat (Avena sativa L.) CC on soil and crop yields in two adjacent irrigated no-till corn (Zea mays L.)-soybean (Glycine max L.) fields on silt loam soils in eastern Nebraska. Field I was grazed twice, while Field II was grazed thrice during a 5-yr study. Cover crop grazing reduced CC biomass by 47 to 87% without impacting soil penetration resistance, bulk density, aggregate stability, hydraulic properties, organic matter fractions, microbial biomass, and crop yields compared to non-grazed CC. In the second study, we evaluated the impact of cattle grazing of corn residue [717-807 animal unit days (AUD) ha-1] and an oat CC (1354 AUD ha-1) on soil compaction parameters including bulk density, penetration resistance, and initial infiltration under two rainfed no-till systems (I and II) on a silty clay loam in eastern Nebraska. System I had one year of corn residue grazing under soybean-corn without horse manure, while System II had one year of CC grazing and another year of corn residue grazing under soybean-wheat (Triticum aestivum L)-corn with horse manure. Dry horse manure application rate in System II averaged 3.92 Mg ha-1. Oat CC was planted following wheat. Corn residue grazing did not impact bulk density, penetration resistance, and infiltration in both Systems. Cover crop grazing in System II did not impact penetration resistance and infiltration but increased bulk density (1.43±0.04 vs 1.38±0.04 Mg m-3), although the increase was below values that affect root growth. Overall, grazing of CC and corn residue has little to no impact on soil properties and crop production and, thus, it could be a viable practice to re-integrate crop with livestock production. Advisor: Humberto Blanco
... Manure application enhanced PLFA biomass, whereas, nitrogen fertilizer had no effect (Lupwayi, 2018). Soil management practices, such as manuring, which result in accumulation of organic C can result in increased microbial biomass and changes in community structure (Peacock et al., 2001). Stark, Condron et al. (2007) also reported that addition of OM ultimately enhanced the soil microbial biomass and activity. ...
... Effects of inorganic fertilizers on soil microbial community structure varied; they can have positive effect directly because of nutrients being added to the soil (Lupwayi et al., 2012) as well as indirect positive effect because of increased root exudates by crops or crop biomass which adds organic C (Geisseler and Scow, 2014). Inorganic fertilization can have direct negative effect due to acidification which can lead to changes in soil microbial community composition (Peacock et al., 2001). Organic manure application is rich in OM, N, P, and K, and other nutrients. ...
... Cellobiose is the main component of microbial hydrolysis of cellulose and a major source of C for soil bacterial communities (Lynd et al., 2002;Li et al., 2009). The results of Peacock et al. (2001) showed that the abundance of soil bacteria has a positive correlation with MBC by applying dairy manure. These results indicated that HM application can stimulate the growth of beneficial families such as Chitinophagaceae, Burkholderiaceae, Beijerinckiaceae, and Cellulomonadaceae, which are mostly involved in biogeochemical cycles of P and C that this practice might increase the nutrient availability and in turn, the yield of the crops. ...
The intensive use of mineral fertilizers to achieve high crop yield has led to soil degradation and poor soil health. Thus, manure application as an alternative to mineral fertilizers can be an effective fertilization strategy to sustain soil health and biodiversity. This study aims to assess the impacts of long-term manure and mineral fertilizers on key soil biochemical and biological indicators. The study was conducted on a 16-year long-term experimental site with six different manure and fertilizer treatments that included no amendments (CK), recommended mineral fertilizer (MF), higher rate of mineral fertilizer (HF), manure application based on the phosphorus requirement (LM), manure application based on the nitrogen requirement (MM), and double the rate of MM treatment (HM). Data showed that higher rates of organic manure application (HM) significantly increased enzyme activities, and soil microbial community phospholipid fatty acid biomass compared to the CK for 0–10 cm soil depth. However, both mineral fertilizer rates did not show any differences in microbial community when compared with the CK for either depth. Soil bacterial community structure was significantly altered by manure and mineral fertilizer application. In comparison to HF and CK, the HM application stimulated some microbial groups (Chitinophagaceae, Burkholderiaceae, Beijerinckiaceae, and Cellulomonadaceae) those are often involved in phosphorus solubilization, nitrogen mineralization, methane degradation, and degradation of complex organic compounds. This study demonstrated that, compared to mineral fertilizers application, the long-term manure application strategy based on different nutrients requirement especially higher manure treatment can be beneficial in enhancing soil biochemical and biological indicators.
... As soil microbes are generally C-limited, the addition of manure can offer a substrate that is either reasonably stable or labile, which is necessary to improve the quantity of total microorganism abundances (Zhang et al. 2015b, a). However, another study suggested that application of ammonium nitrate decreased total microbial PLFAs by 15% in a silt loam soil compared with the addition of no extra nutrients (Peacock et al. 2001). The contradictory result may be due to the fact that the addition of cattle manure does provide both relatively stable and labile (readily available) substrates for the microbial community, whereas the relatively small increase of labile organic C under inorganic fertilizations may be unable to support the substantial growth of microorganisms (Zhang et al. 2015a). ...
... There have been a variety of conclusions produced about the impact of fertilizations on the levels of G + and G − bacteria (Heitkoetter et al. 2017;Li et al. 2020;Song et al. 2022). For instance, Peacock et al. (2001) found that the addition of manure over a period of five years led to an increase in the G-bacterial biomass while leading to a decrease in the G + bacterial biomass. While Ai et al. (2012) presented evidence that a 31-year application of organic fertilizer led to an increase in the amount of G + bacteria. ...
Aims
Application of cattle manure could improve soil fertility by increasing the stability of soil organic carbon (SOC), however, the extent of this effect might depend on the soil layer. This study aims at evaluating the differences in SOC chemistry between topsoil and subsoil caused by cattle manure addition.
Methods
Here, a 90-day pot experiment was used to investigate the SOC chemical structure (¹³C-NMR and FTIR), as well as microbial community composition (PLFA), with cattle manure amended in topsoil (T1M) and subsoil (T2M) and without manure in topsoil (T1) and subsoil (T2).
Results
Application of cattle manure significantly increased SOC, total nitrogen (TN) contents and plant biomass either in topsoil or subsoil. The alkyl C/O-alkyl C (A/OA) ratio of T1M was lower than that of T1, while T2M was greater than that of T2, indicating the SOC of T1M decomposition was delayed but of T2M was promoted. The A/OA ratio of T2M was greater than that of T1M, indicating the decomposition degree of SOC of T2M was greater. The fungi/bacterial PLFA ratio, G⁺/G⁻ PLFA ratio and fungi PLFA were lower in T2M than T1M. RDA analysis demonstrated that O-alkyl C was negatively associated with bacterial and G- PLFA, especially Gemmatimonadetes and Acidobacteria, while positive correlation with fungi PLFA. However, the alkyl C was negatively associated with fungi PLFA, especially Basidiomycota.
Conclusions
The subsoil with cattle manure added promoted bacterial consumed labile C, especially Gemmatimonadetes and Acidobacteria. Therefore, the subsoil with cattle manure added had a higher decomposition degree of SOC when compared with the topsoil with cattle manure added, improving the stability of SOC.
... An apparent suppression of biomass uptake of added substrate was observed following the addition of both types of slurry to the three 14 C-carbohydrate treatments (Table 4.3). However, these findings are not consistent with the concept of slurry application stimulating the soil microbial community and activity that has been reported in some research previously (Kandeler and Eder, 1993, Paul and Beauchamp, 1996, Saviozzi et al., 1997, Lalande et al., 2000, Peacock et al., 2001, Murugan et al., 2014. ...
... Further, the addition of organic amendments, including crop residues and farmyard manure (FYM), to soil has been shown to influence soil microbial communities. Indeed, such addition has predominantly been associated with increases in soil microbial biomass and changes in microbial community structure, particularly the relative abundance of bacteria and fungi within a community (Frostegård et al., 1997, Ritz et al., 1997, Dinesh et al., 2000, Peacock et al., 2001, Lupwayi et al., 2005, Toyota and Kuninaga, 2006, Calbrix et al., 2007, Enwall et al., 2007, Kallenbach and Grandy, 2011, Kätterer et al., 2014, Blaud et al., 2015. In turn, the modifications of microbial biomass and community composition that result from the addition of organic amendments to soil can result in shifts in nutritional competition between r-and K-strategists. ...
The research project aims to enhance organic nutrient management in livestock farms using microbial and enzyme inoculations, with a particular focus on the phosphorus biogeochemical cycle. In order to do this the first approach consists of characterising the chemical and biological properties of farm slurries as a baseline to evaluate possible amendments of the intrinsic properties of the slurry. Consequently, it is pivotal to consider properties such as plant nutrients, i.e., phosphorus, nitrogen and potassium, as well as the microbial community within the slurry. Likewise, attention needs to be paid to soil chemical and biological properties, e.g. pH, salinity and organic matter, as well as to the variety of organisms inhabiting the soil, in order to determine the impact of inoculation on phosphorus cycling and nutrient availability for plant use. Furthermore, it is important to know how soil and its productivity may be influenced by the addition of the inoculated slurry. Of particular interest are also the soil properties which have an effect on plant growth. The pH of soil and, notably, nutrient availability and retention capacity are some of the features on which to direct the research in order to assess the quality of soil and, as a result, the production of a grass crop in livestock farms. The characterisation of these properties will be performed using a variety of approaches, beginning with analysis at laboratory- and mesocosm-scales and progressing to a fieldwork approach in order to evaluate the results directly in a farm system.
... For example, mineral N fertilizer increased the ratio of G+ to G− bacteria in forest soils after 120 days of incubation (Wang et al., 2014). In two other studies, NPK fertilizer increased the relative abundance of G+ bacterial PLFAs in grasslands (Denef et al., 2009) and corn fields (Peacock et al., 2001). Thus, over the long term, G+ bacteria benefit the most from mineral fertilizer-derived nutrients in paddy soils. ...
... Straw replacement increased the abundance of G− bacteria in the 0-20 cm soil layer (Fig. 1b, P > 0.05). This might be because G− bacteria preferentially utilize labile organic C in straw (Peacock et al., 2001). Unexpectedly, straw promoted the abundance of fungal PLFAs in the 10-20 cm soil layer (Table S1). ...
Knowledge remains limited on how the structure of microbial community in paddy soils changes in relation to different types of fertilizers with same amount of nutrients. Thus, here, soil samples were collected at 0-10, 10-20, 20-30, and 30-40 cm depths from a paddy field subjected to four long-term fertilization treatments (no fertilization, mineral fertilization, mineral fertilization combined with rice straw, and chicken manure) and analyzed for microbial biomass and community composition. In unfertilized soils, microbial biomass decreased from 0 to 40 cm (with actinomycetes < gram-positive (G+) bacteria < gram-negative (G−) bacteria < fungi). This ordering was retained after fertilization, but the decline with depth was less pronounced. Both mineral and mineral plus organic fertilization increased the biomass of G+ bacteria compared to G− bacteria (22.7-56.2% increase) and actinomycetes (14.8-52.5% increase). Thus, over the long term, G+ bacteria benefited the most from mineral fertilizer than the other microbial groups. The partial replacement of mineral fertilizer with manure primarily enhanced the abundance of G+ bacteria at 0-30 cm soil depth, whereas replacement with straw enhanced the abundance of fungi at 10-20 cm soil depth. Our findings demonstrate that the structure of the microbial community is strongly impacted by long-term fertilization, independent of fertilizer type.
... Another study reported that organic fertilizer treatment in sweet corn plant led to an increase in the abundance of Gram-negative bacteria [50]. Other studies also showed similar effects on bacterial abundance by the introduction of organic fertilizers [51,52]. The building up of denitrifiers during early stages of plant growth can be explained by the fact that for the benefit of slow growing K-strategic species, the r-strategic species that include Gram-negative bacteria proliferate during early stages and then decline [50,51,[53][54][55]. ...
... Other studies also showed similar effects on bacterial abundance by the introduction of organic fertilizers [51,52]. The building up of denitrifiers during early stages of plant growth can be explained by the fact that for the benefit of slow growing K-strategic species, the r-strategic species that include Gram-negative bacteria proliferate during early stages and then decline [50,51,[53][54][55]. ...
Improper nutrient management is one of the major limitations linked with cultivation of Cajanus cajan. This calls for an urgent need for a promising alternative, employing both bioinoculants and chemical fertilizer. Present study attempted to understand the impact of bioinoculants {Azotobacter chroococcum, Bacillus megaterium, and Pseudomonas fluorescens (ABP)} as their mono-inoculations, triple-inoculation, and their combination with different doses of fertilizer on (a) plant parameters, (b) soil nitrogen (N) economy, (c) resident bacterial community, (d) genes and transcripts involved in N cycle, and to evaluate the extent to which fertilizer could be replaced by ABP without compromising on grain yield. Bradyrhizobium sp. was used in all the treatments (as it was recommended for C. cajan). Combined application of bioinoculants and 75% of recommended dose of fertilizer (RDF) led to 1.28-fold enhancement in grain yield as compared to RDF alone. Apart from exerting a positive impact on grain yield, the combined application of ABP and fertilizer led to an improvement in soil fertility, and modified the culturable rhizospheric bacterial community involved in N cycle. Integrated use of bioinoculants and fertilizer led to better N substrate utilization and hence, metabolic diversity when compared with application of fertilizer alone. An increase in the transcripts of nifH gene at the harvest stage in the soil treated with ABP alone and its combination with fertilizer, over individual treatment with fertilizer was observed. The combined use of ABP and fertilizer shaped the resident bacterial community towards a more beneficial community, which helped in increasing soil nitrogen turnover and hence, soil fertility as a whole.
... Microbial biomass is the living component of soil organic matter, while at the same time microbes change levels of soil organic matter through decomposition. Given the interrelated nature of soil organic matter and microbes, shifts in community composition are often common in observational (Yavitt et al. 2021) and empirical studies (Peacock et al. 2001;Whitman et al. 2016). For example, in systems where tillage disrupts organic matter soil bacterial communities are often demonstrably different in till vs. no-till systems (Tyler 2019;Srour et al. 2020).We also found shifts in bacterial community composition were related to potassium availability. ...
Saint John’s wort, Hypericum perforatum, is a medicinally and ecologically important perennial plant species that has a broad global distribution. Despite the species’ importance, little is known about the factors that structure its microbial communities and the identity of microbes that enhance plant growth and fitness. Here we aim to describe the microbial communities associated with Hypericum perforatum and elucidate factors that structure these communities. We collected H. perforatum root samples in three adjacent habitat types: wet and dry alvars (two types of limestone barren) and fallow agricultural fields (i.e. old-fields), in Jefferson County, New York. We used high-throughput amplicon sequencing to characterize the bacterial and fungal root microbiome. We also quantified aspects of the plant phenotype and soil characteristics to evaluate habitat variables that correlate with the root microbiome. Habitat and plant height were correlated with shifts in microbial community composition. We identified two bacterial taxa positively associated with plant height, both belonging to the bacterial phylum Actinobacteria. This work contributes to our understanding of the environmental determinants of microbial community composition and identifies microbial taxa that may be important in promoting plant growth.
... Microbial community compositions of soil and microbial activities are critical to maintaining soil health; thus, there is a need to consider biological soil properties when the evaluation of impacts of manure application takes place. Applications of dairy manure generally maintain or increase SOC and microbial compositions in comparison to mineral fertilizer treatments (Peacock et al., 2001). For instance, Larkin et al. (2006) found that substrate richness, enzyme activities, bacterial populations, and FAME biomarkers for gram-negative organisms were increased by dairy manure additions in all soils. ...
... Furthermore, the longer crop cycle duration in DC (4 months longer than MC) contributed to higher cumulative autotrophic respiration in DC. Moreover, the incorporation of legume residues in DC increased the input of organic matter, which enhanced the activity of decomposer microorganisms and, consequently, heterotrophic respiration (Peacock et al., 2001). This is supported by the relationship found between soil CO 2 emissions and C and N inputs from aboveground biomass. ...
... Fertilization usually strongly favors the accumulation of bacterial residues (Murugesan and Kumar 2013). The application of organic manure and fertilizers has tendency to increase counts of soil microorganisms, higher microbial biomass, greater enzyme activity and accumulation of carbon (EbhinMasto et al. 2006;Peacock et al. 2001). However, the continual use of chemical fertilizers for a longer period may decline physical, chemical, and microbial properties due to alteration in availability of nutrients in soil. ...
... Additional FAMEs were detected based on mass spectral matching to the NIST Mass Spectral Library (v14) [36,37]. According to [21,23], the EL-FAME biomarkers were attributed to the following microbial groups: Gram-positive bacteria (i14:0, i15:0, a15:0, i16:0, i17:0, and a17:0), Gram-negative bacteria (16:1ω7c, 17:1ω7, 17:0cy, 18:1ω7c, 18:1ω8, and 19:0cy), actinomycetes (10Me16:0, 10Me17:0, and 10Me18:0), fungi (18:2ω6,9c), and arbuscular mycorrhizal (AM) fungi (16:1ω5c). Total bacterial biomass was determined from the sum of biomarkers of Gram-positive and Gram-negative bacteria, actinomycetes, as well as the general bacterial fatty acids 15:0 and 17:0. ...
This study explores the impact of diverse organic fertilizers, including a non-traditional cyanobacteria-based alternative, on soil microbial communities in varying soil types and depths. The research aims to elucidate the effects of these fertilizers on soil microorganisms in certified organic cucumber (Cucumis sativus) field and peach (Prunus persica) orchard settings. Fertilizers were applied either on the soil surface or banded 5 cm below the soil surface, and microbial ester-linked fatty acids (EL-FAMEs) were analyzed in collected soils. Notably, cyanobacteria and Neptune hydrolyzed fish emulsion fertilizers induced significant alterations in the microbial communities of cucumber plots, enhancing microbial biomass and favoring the proliferation of Gram-negative bacteria, Gram-positive bacteria, and actinomycetes compared to other treatments. In the peach orchard, fertilizer choice differentially impacted microbial communities, especially in the first year and at greater soil depths. Notably, the supplementation of poultry manure with cyanobacteria fertilizer resulted in augmented microbial biomass and relative fungal and arbuscular mycorrhizal fungal abundances compared to poultry manure alone. These shifts have promising implications for organic vegetable and fruit cultivation. The study further underscores the potential of cyanobacteria-based fertilizers to reduce reliance on traditional options and minimize manure application, promoting self-sufficiency and benefiting soil microorganisms, plant growth, and the ecosystem. Thus, the research emphasizes the importance of exploring and adopting cyanobacteria-based fertilizers to bolster sustainable agricultural practices.
... Microbial biomass is directly related to soil C and N contents. According to Peacock et al. (2001), the amount and quality of detritus input impact the amount of soil microbial biomass, which can be easily measured, indicating changes in soil organic C content at an early stage (Wiesmeier et al. 2019). Furthermore, microbial biomass C and N reflect the size and activity status of the soil microflora and provide a biologically bonded pool of nutrients in the soil (Nair et al. 2012). ...
This study aimed to examine the dynamics of soil functional indicators under the influence of deadwood in old mixed beech forests in northern Iran. In January and February 2006, several strong wind events occurred in the forest of Khanikan, which led to severe windthrow. All the fallen trees remained in the protected parcel and were not removed. Immediately after tree felling in the studied areas, five common tree species [Fagus orientalis (Fagus), Acer velutinum (Acer), Carpinus betulus (Carpinus), Alnus subcordata (Alnus), and Tilia begonifolia (Tilia)] with the highest abundance of deadwood (with 14 individual trees) were marked as permanent plots for monitoring their effect on soil functions. Wood samples were collected from the trunks and soil samples (0–10 cm depth) from the lower part of deadwood in August 2011, 2016, and 2021. In addition, soil samples were taken from areas that did not have deadwood as control areas. For the study of soil biological parameters, soil samples were collected in August and November (2011, 2016, and 2021). However, for monitoring soil N transformation, soil samples were taken in August, September, November, and December (2011, 2016, and 2021). We found that Alnus and Carpinus deadwood had higher N, K, P, and Ca contents than deadwood of other species. Higher values of C and Mg were observed in Fagus deadwood in the final stages of sampling (2021). Anlus deadwood enhanced the stability of soil aggregates, soil nutrient contents, as well as soil enzyme and microbial activities, and soil fauna and microflora populations during the decay process. Based on our findings, the intensity of soil functions increased in the order control < Fagus < Tilia < Acer < Carpinus < Alnus, which corresponds to the increasing quality of the deadwood of the tree species. Our data emphasize that retaining deadwood is highly effective in boosting carbon and nutrient cycling in forest ecosystems, which may have implications for forest management strategies to improve soil ecological functions and forest sustainability. Although our observations were obtained in an old mixed beech forest, the importance of deadwood on soil functional characteristics can also be assumed in a broader range of forest environments, but this requires further investigation to determine the mechanisms that explain these phenomena.
... On the other hand, phyla such as Firmicutes are highly resistant to environmental stresses and can quickly outgrow other microorganisms (Sass & Parkes, 2011). However, some studies have linked the reduction in Actinobacteria abundance in the soil to increased SOM (Peacock et al., 2001;Fierer, Bradford & Jackson, 2007;Philippot et al., 2009). In our study, both locations (UPVS and PolVS) had very low SOM, which could be related to the very high sand %. ...
Although dumping treated wastewater into soil might provide nutrients and organic matter, it can also expose the ecosystem to biological and chemical risks. A vital indication of soil health and quality is the soil microbial community. The current work used next-generation 16S rRNA gene amplicon sequencing to evaluate the effects of the long-term influx of tertiary treated wastewater (TWW) into Wadi Uranah, a dry valley in Makkah city, Saudi Arabia, on native topsoil bacterial community composition and predicted functions. The findings demonstrated that neither the compositions of microbial communities nor their predicted functions using PICRUSt2 differed significantly ( p > 0.05) between polluted valley soil (PolVS) and unpolluted valley soil (UPVS). Alpha and beta diversity, however, showed that the PolVS samples had a considerably higher level of diversity and variability. Firmicutes, Actinobacteria, Proteobacteria, and Bacteroidetes were the most prevalent phyla in both groups. Noticeable relative variations existed in some metabolic pathways such as cofactor, prosthetic group, electron carrier degradation, aldehyde degradation, and Entner-Doudoroff (ED) pathways. Overall, our findings suggest that because both groups have very similar core microbiomes and functions, the long-term disposal of tertiary TWW into Wadi Uranah may have little to no influence on the composition and function of soil bacterial communities. In addition, the long-term discharge of tertiary TWW after partially treated wastewater’s initial disposal may have helped the native soil microbial community recover.
... Sample weight (g) Among the different fertility levels, FL3 (NP application @ 150 percent RDF) had the highest WBC (4.71 g/kg) for surface soil, but the influence of fertility levels on changes in WBC at subsurface depths of the soil profile was non-significant. The changes in OC concentration caused by graded fertilizer application could be related to differences in organic matter quantity and rate of oxidation by microorganisms (Peacock et al., 2001;Zhang et al., 2010 (Kundu et al., 2007, Ghosh et al., 2012. Soil macroaggregates and microaggregates were significantly higher under FYM application @ 10 t/ha, with an increase of 17.1% and 10% over unfertilized control plots in the surface soil, and 15.5 and 12.2% increases in the sub-surface soil, respectively. ...
The study was undertaken by utilizing an ongoing long-term experiment on continuous cropping at Anand Agricultural University that began in 1980. From 1994 onwards, a modification was made by including Farmyard Manure (FYM) treatments for studying the following objectives: long-term effect of fertility levels with and without FYM on changes in soil organic carbon pools for assessing the role of organics and chemical fertilizers on soil organic carbon buildup and their interrelationship with soil aggregate stability under the pearl millet-mustard-cowpea (F) cropping sequence. Under F1 (FYM @ 10 t/ha) and FL3 (NP application @150 percent of RDF), there was a considerable improvement in the status of Walkley and Black C (WBC), Soil Microbial Biomass Carbon (SMBC), and Total Organic Carbon (TOC) compared to the control in both depths (0-15 and 15-30 cm). Long-term manuring and fertilization practices affect aggregate development and stabilization. In all depths, the highest soil macroaggregates and microaggregates were found when FYM @ 10 t/ha and FL3 (150 percent NP) were applied. Under FYM treated plots and with the greater dose of NP (NP application @150 percent of RDF) in both the surface and sub-surface layers, the maximum water-stable aggregate expressed as mean weight diameter (MWD) was recorded. Furthermore, a significantly positive correlation was observed between SMBC and enzymatic activities (phosphatase, urease, and dehydrogenase) in both the soil depths; indicating the effect of labile C on the biological activities of soil which might be achieved by means of changes in microbial diversity of the soil.
... The asterisk marks (*, **, ***) show significant difference with two-tailed p-value at (p < 0.05, p < 0.01, and p < 0.001), respectively. manures like FYM enhances the microbial activities (Peacock et al., 2001) in the soil and therefore improves the enzymatic (Crecchio et al., 2001) and nutrient profile (Crecchio et al., 2001) of the soil. Variation in MBC and MBN indicates variation in mineralisation and uptake of nutrients due to enhanced microbial activity on organic addition in soil (Gunapala and Scow, 1998;Singh et al., 2015). ...
-Enhancing the productivity of rainfed crops, especially rice, while coping with climate adversities and saving critical natural resources is essential for ensuring the food and nutrition security of a growing population. With this context, the present study was undertaken to validate promising farm innovation and adaptation practices used by small-medium landholding farmers for rice cultivation in eastern Uttar Pradesh (UP), north India, as well as to examine the sustainability of innovative practices for large-scale adoption. For this, a 3-year study comprising extensive field surveys and experiments was undertaken to compare single transplantation (ST) and double transplantation (DT) in rice along with organic addition (farm-yard manure, FYM) on crop growth, yield, climate resilience, soil quality, and overall sustainability i.e., social (women involvements and labour productivity), environmental (water productivity and nutrient use efficiency), and economic (benefit:cost ratio) dimensions of sustainability. Field experiments were conducted in triplicate using two local rice varieties (MotiNP-360 and Sampurna Kaveri) in two agroclimatic zones, namely the middle Gangetic plains and the Vindhyan zone, in the Mirzapur district of eastern Uttar Pradesh. The DT practices of rice with and without farm yard manure (FYM) (replacing at a dose of 25% NPK) were evaluated over conventional methods of rice cultivation (i.e., ST, as control) and analysis was done periodically. The DT practice improved growth (p < 0.05), percent fertile tiller and grain (p < 0.05), and rice yield (15-20% higher than ST), while also improving soil quality, yield indices, water and labour productivity, and the benefit-cost ratio. The DT practice also resulted in early maturity (10-15 days earlier than ST), created more labour days for women, decreased lodging and pest/disease incidence, as well as a subsequent reduction in the use of synthetic chemical pesticides and associated environmental costs. Importantly, the residual effects of FYM application significantly improved (p < 0.05) the grain yield in subsequent years of cropping. Optimizing DT cultivation practices, preferably with FYM input for various agro-climatic regions, is essential for large-scale sustainable rice production under changing climatic conditions.
... 농도 (1 mM)가 낮고, 토양과의 반응시간 (70일)이 길었기 때문에 미생물이 킬레이트제를 분해하는 비율이 높았으며, 더군다나 토양유기물 함량이 많아 미생물의 번성정도가 커서(Peacock et al., 2001;Suh et al., 2010), 수용성 양분을 영양원으로 소모하였기 때문이라 추정한다. 수용성 Fe 3+ 의 함량이 다른 이온보다 많이 증가하였는데 (89 -95%), Fe 은 킬레이트제와 안정화상수 (log K Fe-DTPA = 29.19)가 ...
... In our study, MBC was enhanced by the organic production system relative to the conventional production system. Our findings are in agreement with the previous studies (29)(30)(31)(32). A meta-data analysis study found that organic agriculture can increase MBC by as much as 32% over conventional practices (33). ...
The effects of organic and conventional production systems on crop productivity have been greatly explored, but their effects on soil microbial processes were often neglected. A comparative field study of organic and conventional production systems was conducted at the Tennessee State University research farm to determine soil heterotrophic respiration and microbial biomass carbon. Leafy green vegetables were grown in a conventional production system in an open field, and they were grown in an organic production system, using three different row covers (agribon cloth, insect net, and plastic), and in an open field. Soil samples (0-15cm) were collected from the two production systems. Soil heterotrophic respiration rate (RH), microbial biomass carbon (MBC), and biomass-specific heterotrophic respiration rate (the inverse is used as a proxy for microbial carbon use efficiency) were quantified. The results showed that the conventional production system significantly increased RH relative to the organic system. Organic production system, however, significantly enhanced MBC and reduced biomass-specific respiration rate indicating an increase in carbon use efficiency. Although MBC remained unchanged among the row covers, insect net increased RH and biomass-specific heterotrophic respiration rate. Our results suggest that the organic production system not only promoted soil microbial abundance but also limited soil heterotrophic respiration to the atmosphere governed by the elevated carbon use efficiency.
... Integrated use of inorganic fertilizer with organic fertilizer has been reported to improve soil fertility and crop yield sustainably than the sole application of inorganic fertilizer [7]. The application of organic fertilizers like cattle manure increases the accumulation of organic C in the soil, which in turn induces a change in the microbial community structure and stimulates the microbial biomass [47]. ...
... Even though we did not measure it, manure typically changes soil pH and increases the availability of nutrients, which in turn increases microbial biomass (84,85). This shift in pH and biomass affects the structure of the microbial soil community (86)(87)(88). Such changes in the soil may also affect the development of larger organisms. ...
... Manure-derived organic matter plays a positive role in climate change mitigation by soil carbon sequestration [4]. Positive effects of soil treatment with manure on total soil carbon, nitrogen, microbial biomass carbon, and dehydrogenase activity in soil has been generally observed [5,6]. However, the time scale impacts on treated soil and its properties after application is limited by the rate of decomposition of complex compounds in the manure and availability and leachability of nutrients [4]. ...
Background
The farmyard manure application maintains quality of arable soils, provides nutrients, mitigates climate change by soil carbon sequestration. Biochar and other complex carbon rich amendments may stabilize organic matter derived by composting and decelerate organic carbon mineralization. However, how the combined utilization of biochar, humic substances and manure effects on soil chemical and biological properties have been least explored, especially their effect on soil basal and substrate induced respirations are needed to be further explored. Therefore, the potential of biochar and Humac (a commercial humic substances product) in combination with manure to improve the soil properties and plant growth was investigated in this experiment using barley under a short-term (12 weeks) and maize under long-term (following 12 weeks, a total of 24 weeks) cultivation.
Results
In the early phase of cultivation (12 weeks) Humac- or biochar-enriched manures (M + H, M + B, respectively) enhanced the contents of nutrient elements (carbon + 5.6% and + 7%, nitrogen + 6.7% and − 5%, sulphur − 7.9% and + 18.4%), the activity of enzymes including (β-glucosidase + 32% and + 9.6%, phosphatase + 11% and 6.3%), and dry aboveground biomass (+ 21% and + 32%), compared to the control and manure-treated soil. However, these impacts of M + H and M + B manures were reduced under longer period, i.e., at the experiment end (24 weeks). After 24 weeks of cultivation, a decrease in absolute values of all determined enzyme activities indicated putative reduction of mineralization rate due to presumed higher recalcitrance of manure-derived organic matter, with Humac, biochar amendments. Increased stability of soil organic matter reduced microbial activity due to lower availability of nutrients. Possibly, the shortened period of manure maturation could help preserve a higher amount of less degraded organic matter in the enriched manures to counteract these observed features.
Conclusions
We summarized that the biochar and humic substances combined with manure have the potential to improve the soil characteristics, plant biomass and soil health indicators but the improvements faded away in a cultivation time-dependent manner. Further studies are required to explore the structure and functioning of microbial activities under long-term experimental conditions.
Graphical abstract
... Moreover, soil alkalinization due to manure can raise the availability of soil nutrients to plants and it can thereby increase plant growth [52]. High values of soil pH may also induce variations in soil enzyme activity, increases in microbial biomass, and changes in microbial community structure, which might be important mechanisms for alleviating acid stress and metal(loid) toxicity into soil by providing a better environment for the growth of plants [82]. Thus, in the present study, the better growth of S. triandra plants found in the different treatments with respect to the control condition is almost certainly attributable to the manure use, and manure capacity to raise nutrient availability into soil. ...
Past mining extraction activities still have a negative impact in the present time, the resulting metal(loid) contaminated soils affecting both the environment and human health. Assisted phytostabilization technology, combining soil conditioner application to immobilize metal(loid)s and plant growth to reduce erosion and leaching risks, is a useful strategy in the restoration of metal(loid) contaminated lands. However, contaminants will respond differently to a particular amendment, having their own specific characteristics. Therefore, in multi-contaminated soils, soil conditioner combination has been suggested as a good strategy for metal(loid) immobilization. In the present study, in a mesocosm experiment, organic (biochar and manure) and inorganic (ochre) amendments were evaluated in single and combined applications for their effect on metal(loid) stabilization and Salix triandra growth improvement, in an arsenic and lead highly contaminated soil. Specifically, the effects of these amendments on soil properties, metal(loid) behavior, and plant growth were evaluated after they aged in the soil for 6 months. Results showed that all amendments, except biochar alone, could reduce soil acidity, with the best outcomes obtained with the three amendments combined. The combination of the three soil conditioners has also led to reducing soil lead availability. However, only ochre, alone or combined with the other soil fertilizers, was capable of immobilizing arsenic. Moreover, amendment application enhanced plant growth, without affecting arsenic accumulation. On the contrary, plants grown on all the amended soils, except plants grown on soil added with manure alone, showed higher lead concentration in leaves, which poses a risk of return of lead into the soil when leaves will shed in autumn. Considering that the best plant growth improvement, together with the lowest increase in lead aerial accumulation, was observed in manure-treated soil, the addition of manure seems to have potential in the restoration of arsenic and lead contaminated soil.
... Based on our simulations, the soil Cu contamination was expected to substantially modify the proportion of available N in soils with the increase in NH 4 -N stock at the expense of NO 3 -N. NH 4 -N accumulation and the large expected de-crease in NO 3 -N/NH 4 -N ratio in contaminated soils (around 50 % for the 60 % WHC) may lead to a shift in plant community structures with different preferences in N assimilation (Cui and Song, 2007;Peacock et al., 2001). Therefore, Cu stress could not only have implications in microbial community patterns as a stressor but could also induce further shifts due to N species redistributions in soils. ...
Continental biogeochemical models are commonly used to predict the effect of land use, exogenous organic matter input or climate change on soil
greenhouse gas emission. However, they cannot be used for this purpose to investigate the effect of soil contamination, while contamination affects
several soil processes and concerns a large fraction of land surface. For that, in this study we implemented a commonly used model estimating soil
nitrogen (N) emissions, the DeNitrification DeCompostion (DNDC) model, with a function taking into account soil copper (Cu)
contamination in nitrate production control. Then, we aimed at using this model to predict N2O-N,
NO2-N, NO-N and NH4-N emissions in the presence of contamination and in
the context of changes in precipitations. Initial incubations of soils were performed at different soil moisture levels in order to mimic expected
rainfall patterns during the next decades and in particular drought and excess of water. Then, a bioassay was used in the absence or presence of
Cu to assess the effect of the single (moisture) or double stress (moisture and Cu) on soil nitrate production. Data of nitrate
production obtained through a gradient of Cu under each initial moisture incubation were used to parameterise the DNDC model and to estimate
soil N emission considering the various effects of Cu. Whatever the initial moisture incubation, experimental results showed a
NO3-N decreasing production when Cu was added but depending on soil moisture. The DNDC-Cu
version we proposed was able to reproduce these observed Cu effects on soil nitrate concentration with r2 > 0.99 and RMSE < 10 % for all treatments in the DNDC-Cu calibration range (> 40 % of the water holding capacity) but
showed poor performances for the dry treatments. We modelled a Cu effect inducing an increase in NH4-N soil concentration and
emissions due to a reduced nitrification activity and therefore a decrease in NO3-N, N2O-N and
NOx-N concentrations and emissions. The effect of added Cu predicted by the model was larger on N2-N
and N2O-N emissions than on the other N species and larger for the soils incubated under constant than variable moisture. Our
work shows that soil contamination can be considered in continental biogeochemical models to better predict soil greenhouse gas emissions.
... Long-term manure application can also increase the soil microbial biomass, which provides better soil conditions for crop growth (Peacock et al. 2001). In the present study, the microbial biomass of C, N and P was the highest under the MNPK treatment and did not show significant differences among the NK, PK and NPK treatments (Fig. 1). ...
Understanding the impact of biological activities on the soil phosphorus (P) distribution under long-term fertilizer application can facilitate better soil P fertility management. Therefore, the primary objectives of this study were to investigate the effect of long-term (since 1981) fertilizer application on the soil P fractions and microbial community and to evaluate correlations between the microbial community structure and P distribution. The following treatments were implemented in a long-term field trial: no fertilization (CK), inorganic N and K (NK), inorganic P and K (PK), inorganic N, P and K (NPK) and manure+NPK (MNPK) fertilization. The study showed that the soil pH, soil organic carbon and total and available N and P concentrations were considerably higher in the MNPK treatment than in the CK treatment. The soil microbial biomass C, N and P concentrations were also significantly higher in the MNPK treatment than in the CK treatment. Among fertilization treatments, the β-1,4-glucosidase, α-1,4-glucosidase, urease, acid phosphatase and phosphodiesterase activities were the highest in the MNPK treatment. Compared to inorganic fertilization, the MNPK treatment increased the labile soil P fractions and decreased the residual soil P concentration. Continuous fertilization significantly affected the soil microbial composition. The total phospholipid fatty acid (PLFA) concentrations in the NK, PK, NPK and MNPK treatments were 23.3, 43.1, 48.7 and 87.7% higher, respectively, than in the CK treatment. A significant correlation was observed between the microbial community and soil P fractions. Moreover, the aggregated boosted tree (ABT) model showed that among the various soil biochemical properties, the total PLFA concentration was the factor that most influenced the active P pool, accounting for 35.4% of the relative influence of all soil biochemical properties examined. These findings reveal that combined manure and inorganic fertilizer application is a better approach than applying inorganic fertilizer alone for sustaining long-term P fertility by mediating soil biological activity.
... The bacterial community may then be significantly altered in response to the individual components of the added waste and with respect to time. Therefore, it is important to understand the major factors in shaping the soil prokaryotic community to pave the way for improving soil quality and carrying out proper fertilization using alternative byproducts such as digestate (Peacock et al., 2001). ...
There is a renewed global awareness to improve soil health through the intensification and management of organic inputs such as the application of animal waste–based digestate and other types of organic fertilizers to the soil. The objective of this study was to evaluate the influence of different types of animal waste–based digestate application on soil prokaryotic diversity and composition in an agricultural cropping system over a period of 3 years, cultivated with three different annual cereal crops (spring wheat, triticale, and barley). Treatments were laid out in a randomized design with five conditions (three replicates per condition): fertilizer treatments included three different types of digestate (pig manure, chicken manure, and cow manure digestates), synthetic mineral nitrogen, and unfertilized control. Prokaryotic soil communities were characterized by Illumina MiSeq sequencing. The three most abundant phyla identified were Actinobacteria, Acidobacteria, and Proteobacteria, which accounted for over 55% of the total prokaryotic community. Other phylogenetic groups such as Verrucomicrobia and Bacteroidetes were also identified as part of the native soil microbiota. It was observed that the period of digestate application did not significantly influence the prokaryotic diversity in the soil. On the contrary, sampling time was a major factor in driving β-diversity. A correlation with soil pH was also observed for several taxonomic groups, indicating its importance in shaping prokaryotic community composition. Our study showed that the richness and diversity of the soil prokaryotic community were not affected by digestate application, while other factors such as the yearly crop varieties and seasonal/climate changes were the major contributors to differentiating the prokaryotic community composition over time.
... Even though we did not measure it, manure typically changes soil pH and increases the availability of nutrients, which in turn increases microbial biomass (84,85). This shift in pH and biomass affects the structure of the microbial soil community (86)(87)(88). Such changes in the soil may also affect the development of larger organisms. ...
Insects are integral to terrestrial life and provide essential ecosystem functions such as pollination and nutrient cycling. Due to massive declines in insect biomass, abundance, or species richness in recent years, the focus has turned to find their causes. Anthropogenic pollution is among the main drivers of insect declines. Research addressing the effects of pollutants concentrates on aquatic insects and pollinators, despite the apparent risk of contaminated soils. Pollutants accumulating in the soil might pose a significant threat because concentrations tend to be high and different pollutants are present simultaneously. Here, we exposed queens of the black garden ant Lasius niger at the colony founding stage to different concentrations and combinations of pollutants (brake dust, soot, microplastic particles and fibers, manure) to determine dose-dependent effects and interactions between stressors. As proxies for colony founding success, we measured queen survival, the development time of the different life stages, the brood weight, and the number of offspring. Over the course of the experiment queen mortality was very low and similar across treatments. Only high manure concentrations affected the colony founding success. Eggs from queens exposed to high manure concentrations took longer to hatch, which resulted in a delayed emergence of workers. Also, fewer pupae and workers were raised by those queens. Brake dust, soot and plastic particles did not visibly affect colony founding success, neither as single nor as multiple stressors. The application of manure, however, affected colony founding in L. niger negatively underlining the issue of excessive manure application to our environment. Even though anthropogenic soil pollutants seem to have little short-term effects on ant colony founding, studies will have to elucidate potential long-term effects as a colony grows.
... In post-agricultural landscapes that target temperate forest restoration, we suggest active management to alter the soil properties to support tree seedlings. For example, using soil amendments such as biochar or compost could greatly improve the organic matter content and water holding capacity of the soils surface (Peacock et al. 2001;Blumenthal et al. 2003;Mulumba & Lal 2008;Laird et al. 2010;Biederman et al. 2017). These amendments can shift microorganism communities toward those that promote native tree species (Lehmann et al. 2011). ...
Overcoming establishment limitation is an integral task during forest restoration on degraded lands for tree species whose prominence is declining, such as those in the Quercus genus. Fallow agricultural lands are suitable for forest restoration efforts by planting seedlings; however, tree seedling success may be limited due to soil conditions that are distinct from relict forests. Here, we assessed soil nutrient content, physicochemical parameters, and microorganism function via soil enzyme activity from five restorations that were implemented 0, 7, 10, 50 or 100‐years ago. We planted Q. macrocarpa (bur oak) seedlings in soils collected from each site for 5 months before collecting dry biomass, used as a proxy for size. We found that Q. macrocarpa seedlings had the largest total biomass when they were planted in soils from older restorations. There was a significant positive correlation of the amount of soil carbon, nitrogen, organic matter and soil moisture with tree size, and these soil parameters increased with forest age. We assessed seedling roots for mutualistic ectomycorrhizal fungi, but we did not find associations between their presence and tree size. Forest restoration is a complex process which can take many decades, but we suggest that reforestation may be accelerated by implementing active soil restoration to increase soil carbon, nitrogen, and water holding capacity prior to planting tree seedlings in target sites. Active soil restoration may aide in overcoming a significant portion of establishment limitation of ecologically important tree species that typically do not fare well in early‐stage restorations. This article is protected by copyright. All rights reserved.
... These laboratory measures are considered 'gold standards' for assessing biological soil health (Fuhrer, 2020). As a result, there is a plethora of evidence confirming they are highly sensitive to practices such as reduced tillage (Houben et al., 2018;Wardle et al., 1999), crop rotation (McDaniel and Grandy, 2016), manure addition (Ringelberg et al., 2002), and cover crops (Finney et al., 2017). However, these measures are also spatially and temporally variable (Cambardella et al., 1994;Culman et al., 2013;Debosz et al., 1999), and therefore sometimes difficult to detect changes in management practices. ...
Recognition that soil resources are fragile has increased interest in soil health promoting practices (SHPPs) and ways to monitor changes in agricultural soil health. To enhance this effort, inexpensive and user-friendly methods are needed. Especially methods to measure biological activity, which is central to soil health but current methods are expensive and inconvenient. Our objective was to quantify biological activity by monitoring decomposition (via mass loss) of common household items [green and rooibos tea (Camellia sinensis and Aspalathus linearis), bleached cotton (Gossypium hirsutum), and birch craft sticks (Betula spp.)], and compare these results with common laboratory measurements of biological soil health (microbial biomass carbon and nitrogen, permanganate oxidizable carbon, and potentially mineralizable carbon and nitrogen). First, we compared both strategies using correlation, including with the yield of the dominant crop in the region [maize (Zea mays L.)]. Second, we evaluated their response to several long-term SHPPs: (i) biochar, (ii) winter cover crops, (iii) nitrogen fertilizer, (iv) no-tillage, (v) diversified rotation, (vi) perennial crops, (vii) crop residue addition/removal, and (viii) prairie restoration. Correlations between decomposition and laboratory measurements were poor and often negative. Maize yield positively correlated with tea decomposition but not with the laboratory indicators. Based on ‘signal-to-noise’ ratios, or magnitude of SHPP treatment effect compared to variability, measurements of decomposition, especially mass loss of rooibos tea (for 4 days) and bleached cotton (for 35 days), outperformed many of the laboratory indicators in detecting treatment differences. Decomposition was also easier and less expensive than laboratory methods indicating it is a simple, yet scientifically defensible, alternative for measuring soil biological health in agroecosystems.
... Soil microbial PLFA. Several PLFA based studies reported significant differences in soil microbial community composition and abundance under different fertilizer management practices 49,50 . Soil microbial community (SMC) are sensitive to external application of N and P 51,52 . ...
Phosphorus (P) is the second most important macronutrient that limits the plant growth, development and productivity. Inorganic P fertilization in podzol soils predominantly bound with aluminum and iron, thereby reducing its availability to crop plants. Dairy manure (DM) amendment to agricultural soils can improve physiochemical properties, nutrient cycling through enhanced enzyme and soil microbial activities leading to improved P bioavailability to crops. We hypothesized that DM amendment in podzol soil will improve biochemical attributes and microbial community and abundance in silage corn cropping system under boreal climate. We evaluated the effects of organic and inorganic P amendments on soil biochemical attributes and abundance in podzol soil under boreal climate. Additionally, biochemical attributes and microbial population and abundance under short-term silage corn monocropping system was also investigated. Experimental treatments were [P0 (control); P1: DM with high P2O5; P2: DM with low P2O5; P3: inorganic P and five silage-corn genotypes (Fusion RR, Yukon R, A4177G3RIB, DKC 23-17RIB and DKC 26-28RIB) were laid out in a randomized complete block design in factorial settings with three replications. Results showed that P1 treatment increased acid phosphatase (AP-ase) activity (29% and 44%), and soil available P (SAP) (60% and 39%) compared to control treatment, during 2016 and 2017, respectively. Additionally, P1 treatments significantly increased total bacterial phospholipids fatty acids (ΣB-PLFA), total phospholipids fatty acids (ΣPLFA), fungi, and eukaryotes compared to control and inorganic P. Yukon R and DKC 26-28RIB genotypes exhibited higher total bacterial PLFA, fungi, and total PLFA in their rhizospheres compared to the other genotypes. Redundancy analyses showed promising association between P1 and P2 amendment, biochemical attributes and active microbial population and Yukon R and DKC 26-28RIB genotypes. Pearson correlation also demonstrated significant and positive correlation between AP-ase, SAP and gram negative bacteria (G−), fungi, ΣB-PLFA, and total PLFA. Study results demonstrated that P1 treatment enhanced biochemical attributes, active microbial community composition and abundance and forage production of silage corn. Results further demonstrated higher active microbial population and abundance in rhizosphere of Yukon R and DKC 26-28RIB genotypes. Therefore, we argue that dairy manure amendment with high P2O5 in podzol soils could be a sustainable nutrient source to enhance soil quality, health and forage production of silage corn. Yukon R and DKC 26-28RIB genotypes showed superior agronomic performance, therefore, could be good fit under boreal climatic conditions.
... Increasing evidence suggest that responses of microbial diversity and activity to different organic strategies are largely determined by the amount and composition of organic substrates (Bowles et al., 2014;van der Bom et al., 2018). Compared with cover cropping, adding animal manure to the soil is a fast and convenient way to provide a large amount of soil organic carbon (Brennan and Acosta-Martinez, 2017), leading to improved crop growth and suppressed pests and diseases by enhancing soil microbial activity and diversity (Peacock et al., 2001;Shannon et al., 2002;Jilani et al., 2007;Ding et al., 2016). Yet, there are some reports on a significant reduction of fungal and bacterial abundance, particularly Acidobacteria, under cattle and livestock manure amendment (Parham et al., 2003;Sun et al., 2015). ...
Food systems need to become more sustainable. There is a need to investigate the agricultural management components that address the sustainability better. Long crop rotations are suggested to be environmentally friendly, yet, little is known how soil microbial communities may be affected by long-term rotation under organic cropping with cover crops and manure and conventional cropping with different nitrogen rates. We examined the composition and diversity of soil bacterial and fungal communities in a five-field crop rotation at the beginning and end, respectively in 2013 and 2018. Our analysis revealed that bacterial and to a lesser extent fungal diversity increased by the end of the rotation in all organic treatments and in conventional treatments with low to medium nitrogen rate (20‐100 kg of nitrogen per hectare). Conventional treatment with no added nitrogen decreased bacterial and fungal diversity. Nitrogen rate of 150 kg/ha decreased only bacterial diversity, while the impact on fungal diversity was neutral. Crop rotation significantly increased the relative abundance of bacterial taxa involved in nitrification and denitrification. Of fungal functional groups, the relative abundance of pathogenic functional groups decreased and mycorrhizal groups increased during crop rotation and especially with added cover crops. Our results suggest that crop rotation may outperform cropping systems in structuring soil microbial communities.
... Cox et al. (2001), Reeve et al. (2012), Tautges et al. (2016), Calderón et al. (2018), and Shiwakoti et al. (2020) also showed benefits of compost/manure application to a range of dryland soil properties including soil organic C, macronutrients, and enzyme activities. These findings are also consistent with research conducted in more humid regions (Flieβbach & Mäder, 2000;Peacock et al., 2001). ...
Organic dryland wheat (Triticum aestivum L.) is an important crop in Utah and the Intermountain Western United States; however, growers face numerous challenges maintaining yield, grain quality, soil fertility, and health. Wheat yields in the West are severely constrained by lack of rainfall, so dryland organic wheat farmers generally do not grow cover crops due to the risk of subsequent crop failure or apply soil amendments due to the inability to recoup application costs in the short‐term. Compost may have significant non‐nutritive as well as nutritive effects on soil processes, however, potentially changing calculations of perceived costs vs benefits. The goal of this study was to quantify the effects of a one‐time compost application on soil health, yield, and crop quality in an organic dryland wheat‐fallow system in Northern, UT. Four rates of compost, applied once, (0, 12.5, 25, and 50 Mg ha−1 DW) were compared to anhydrous ammonia (50 kg N ha−1) applied at planting. Mineralizable carbon, microbial biomass, and phosphatase enzyme activity increased significantly at all compost rates, while available soil phosphorus increased at the 25 and 50 Mg ha−1 rates and total soil N at the 50 Mg ha rate−1. Soil moisture was generally no different between treatments. Wheat yield was significantly greater three years after application at the 50 Mg ha−1 compost rate only, with no response to conventional fertilizer. A lack of yield response to conventional fertilizer suggests that non‐nutritive benefits of improved soil health were responsible for improved yields at the high compost rate. This article is protected by copyright. All rights reserved Effects of a single compost application persist in organic dryland wheat systems Nutritive and non‐nutritive effects of compost on wheat yield and quality are important Improved soil health is responsible for yield increases
... Imbalanced fertilizers application for a long-time can reduce the growth of these bacteria (Eo and Park, 2016;Bei et al., 2018). Similarly, manure application decreased the growth of Actinobacteria compared to that of inorganic fertilizers (Peacock et al., 2001). Bacterial communities associated with carbon and nitrogen cycling can be described by their relations with soil carbon and nitrogen fractions. ...
Soil bacterial community structure, enzyme activities, and their relationships to soil carbon and nitrogen in response to long-term fertilization remain poorly understood. Therefore, the objective of this study was to evaluate soil carbon and nitrogen fractions, enzyme activity, and bacterial community structure at 0-15, 15-30, and 30-60 cm depths after 34-yr of continuous application of manure and inorganic fertilizers. The study had a randomized complete block design with six treatments and three replications. Treatments were inorganic nitrogen fertilizer only (N), nitrogen plus phosphrous fertilizers (NP), manure (M), nitrogen plus manure (NM), nitrogen plus phosphorus plus manure (NPM), and unfertilized control (CK) in a winter wheat (Triticum aestivum L.) monoculture system. Most soil carbon and nitrogen fractions at 0-15 and 15-30 cm were greater with M, NM, and NPM, and winter wheat yield was greater with NPM than other treatments. The NPM increased β-glucosi-dase, β-xylosidase, and β-N-acetylglucosidase compared to other treatments at all depths. Soil bacterial Shannon index was similar among treatments at 0-15 and 15-30 cm and lower in N and NP than other treatments at 30-60 cm. Compared to CK, inorganic and manure fertilization increased relative abundances of Gemmatimo-nadetes and Bacteroidetes but decreased those of Nitrospirae, Planctomycetes, and Latescibacteria. Increases in soil enzyme activities and bacterial communities after long-term application of inorganic N and P fertilizers and manure was related to increased substrate availability. Overall, a combination of chemical fertilizers and manure can enhance soil health and quality through increased soil organic matter component, enzyme activity, and bacterial abundance.
... The microbial biomass is related to the content of C and N. According to Peacock et al. [53], the amount and quality of detritus input influence microbial biomass. The soil microbial biomass can be used to indicate changes in the soil organic C content because the soil microbial biomass pool is easily measurable [39]. ...
Disturbances play an essential role in the shaping of temporal and spatial heterogeneity in natural community structures. The aim of this study was to provide an assessment of the deadwood influence on the chemical and biochemical properties of soils in a landslide area. The samples used to determine soil properties were collected from the entire landslide area, with locations distributed on a regular grid (50 × 50 m). The soil samples were collected from directly under the logs, and background soil samples were taken 1 m from the deadwood logs. The effect of the deadwood decomposition process was visible in the total organic carbon (C) and nitrogen (N) content and microbial activity of the soil. An increase in the enzyme activity and microbial biomass of the soil from directly beneath the deadwood was noted. In this study, it was found that a greater stock of deadwood was present in the accumulation zone, which resulted in a stronger effect of the released components on the soil cover. In order to restore landslide soils, microbial activity can be effectively stimulated by leaving deadwood on the landslide surface.
... Manure application increases the C input and crop residues within the soil, which enhances the soil C sequestration rate and increases soil productivity (Cai et al. 2019). Manure can also increase microbial biomass and activity within the soil, which provides a better environment for crop growth (Peacock et al. 2001). In this study, manure application treatments significantly increased crop yield compared to the inorganic fertilization treatments. ...
Soil organic carbon (SOC) and nitrogen (N) are two of the most important indicators for agricultural productivity. Therefore, the primary objectives of this study were to investigate the changes in SOC and N within the deep soil profile (up to 100 cm) and their relationships with crop productivity under the influence of long-term (since 1990) fertilization in the wheat-maize cropping system. Treatments included the CK (control), NP (inorganic N and P fertilizers), NPK (inorganic N, P and potassium fertilizers), NPKM (NPK plus manure), and M (manure). The crop yield and the properties of the topsoil were measured yearly from 2001 to 2009. While, C and N contents were measured at five different depths in 2001 and 2009. The results showed that the wheat and maize yield decreased between 2001 and 2009 under the inorganic fertilizer (NP and NPK) treatments. The average yield between 2001 and 2009 under the NP, NPK, NPKM, and M treatments (compared with the CK treatment) increased by 38, 115, 383, and 381%, respectively, for wheat and 348, 891, 2738, and 1845% respectively, for maize. Different long-term fertilization treatments significantly changed the coarse free particulate (cfPOC), fine free particulate (ffPOC), intramicroaggregate particulate (iPOC), and mineral-associated (mSOC) organic carbon fractions. In the experimental years of 2001 and 2009, soil fractions occurred in the following order for all treatments: mSOC>cfPOC>iPOC>ffPOC. All fractions were higher under the manure application treatments than under the inorganic fertilization treatments. Compared to the inorganic fertilization treatments, manure input enhanced the stocks of SOC and total N within the surface layer (0–20 cm) but decreased SOC and N within the deep soil layer (between 80 and 100 cm). This reveals the efficiency of manure for higher yield productivity and a lower risk of vertical loss of nutrients, especially N, compared to inorganic fertilization treatments. Our findings recognize the potential opportunities for understanding deep soil C and N dynamics that can then help to mitigate climate change and to maintain soil health within the agricultural production system.
... They can have direct positive effect because of the nutrients being added to the soil (Lupwayi et al. 2012) as well as indirect positive effect because of the increased root exudates by crops or crop biomass which increase OC (Geisseler and Scow 2014). In contrast, inorganic fertilization can have direct negative effect due to acidification, decreasing SOC and TN and lowering microbial activity (Peacock et al. 2001). ...
Manure application can enhance soil fertility and crop yield; however, knowledge of optimum application rates of manure is needed to prevent negative impacts on soils and environment. This study was aimed to compare the long-term effects of manure and inorganic fertilizer application at different rates on soil nutrients, aggregate stability, organic carbon, and nitrogen in different aggregate size fractions. The experiment was conducted on a long-term manure site under a randomized complete block design with six treatments: three manure [low manure (LM; application based on phosphorous requirement), medium manure (MM; application based on nitrogen requirement), high manure (HM; two times prescribed nitrogen rate)], two chemical fertilizer [medium fertilizer (MF; suggested inorganic fertilizer rate), high rate of fertilizer (HF)], and control (CK; no manure nor fertilizer). Manure application maintained soil pH, improved nutrient availability and aggregate stability compared to the CK. The HM treatment increased aggregate-associated soil organic carbon (SOC) and total nitrogen (TN) concentration by 40 to 50% in all size fractions as compared to the CK. Further, HM increased particulate organic matter (POM) by 1.2 times as compared to the CK, while inorganic fertilizer application did not alter these parameters compared to the CK.
... Noteworthy, the magnetic biochar also significantly reduced the PLFA concentrations of G − bacteria. G − bacteria biomass is associated with monounsaturated fatty acids, which correspond to a high organic matter content and substrate availability (Peacock et al., 2001). Accordingly, the magnetic biochar used in this study could potentially reduce the soil quality. ...
Magnetic biochar has been widely used in the removal of aquatic pollutants due to its
strong adsorption capacity and recyclability. However, the nutrient deficiency caused
by magnetic biochar reduces plant performance and limits its use. The effects of
magnetic biochar (derived from either eucalyptus wood or pig manure compost) on soil
Cd, Zn, and Pb bioavailability to Phragmites australis L. (reed) and soil microbial
community were investigated in a pot experiment. We also examined treatments of
magnetic biochar with P supplementation and unmodified biochar with Fe addition to
elucidate the mechanism by which magnetic biochar affects plant growth. We found
that the addition of magnetic biochar significantly reduced the concentrations of
available heavy metals in soil and inhibited heavy metal uptake by reeds. It also
promoted the formation of iron plaque on reed roots to inhibit metal translocation.
However, compared to unmodified biochar, magnetic biochar reduced reed
performance, as indicated by the reduced plant biomass and photosynthetic ability,
and it also reduced the biomass of soil bacteria and fungi. This was due to the
interception of P by the iron plaque and the reduced concentration of soil available P.
Collectively, although magnetic biochar exhibited a strong potential for heavy metal
remediation, P supplementation is recommended to maintain plant performance and
soil health when applying magnetic biochar.
... Long-term application of inorganic fertilizers containing nitrogen and phosphorus will result in the assimilation of more nitrogen and phosphorus into microorganisms, thereby improving soil MBN and MBP. Long-term application of organic fertilizer can also speed up the decomposition of organic carbon sources by microorganisms, and more substantial assimilation rates can increase soil nutrient contents and ensure higher microbial biomass [63][64][65][66]. ...
Background: Poplar (Populus) is a genus of globally important plantation trees used widely in industrial and agricultural production. However, poplar is easily damaged by Micromelalopha troglodyta and Hyphantria cunea, resulting in a decline in poplar quality. Due to their strong insect resistance, Bt toxin-encoded Cry genes have been widely adopted in poplar breeding; however, potential adverse effects of Cry1Ah1-modified poplars on the ecological environment have raised concerns.
Results: In this study, we comprehensively analyzed the structural and functional composition of the rhizosphere microbiome in field-grown transgenic Bt poplar.
Conclusions: Our analysis of soil chemistry patterns revealed that soil alkaline nitrogen, soil available phosphorus, and microbial biomass nitrogen and phosphorus levels were improved, whereas microbial biomass carbon declined in Cry1Ah1-modified poplar rhizosphere samples. We applied metagenomic sequencing of Non-Transgenic (NT) and Cry1Ah1-modified poplar rhizosphere samples collected from a natural field; the predominant taxa included Proteobacteria, Acidobacteria, and Actinobacteria. We also identified microbial functional traits involved in membrane transport, amino acid metabolism, carbohydrate metabolism, and replication and repair in NT and Cry1Ah1-modified poplars. Together, these results demonstrate that the NT and Cry1Ah1-modified poplar rhizosphere microbiomes had similar diversity and structure. These differences in relative abundance were observed in a few genera but did not affect the primary genera or soil.
In acid soils, majority of the applied phosphorus (P) transforms to sparingly soluble Fe (P Fe) and Al phosphates (P Al), triggering rampant P deficiency. This study aimed to evaluate the impact of long-term (46-years) nutrient management practices on P fractions and P adsorption-desorption behaviour of an acid soil with a soybean-wheat cropping system. Out of ten treatments employed in this experiment, eight most pertinent to the study, viz., control, N (100 % of recommended N fertilizer), NP (100 % of recommended N and P fertilizers), 50 % NPK (50 % of recommended N, P, and K fertilizers), NPK, 150 % NPK, NPK+FYM (100 % of recommended N, P, and K fertilizers with farmyard manure), and NPK+Lime (100 % of recommended N, P, and K fertilizers with lime) were selected. The findings revealed that amorphous Fe and Al, which play a significant role in P fixation, increased due to cultivation. The treatment 150 % NPK recorded the highest available P (104 mg kg-1), followed by NPK+FYM (84.1 mg kg-1) at 0-15 cm depth. The P Fe was the dominant inorganic P fraction (25-46 %) while soluble and loosely bound P (the easiest plant available fraction) was the lowest (0.9-1.9 %). The long-term cultivation led to an accumulation of P Fe and P Al fractions while caused dissolution of calcium bound P (P Ca). The highest content of organic P (P o) was recorded with NPK+FYM (234 kg ha-1). The analysis of Langmuir and Freundlich isotherms indicated that NPK+FYM and 150 % NPK reduced the P adsorption maxima to 341 and 231 mg kg-1 , respectively, compared to 406 mg kg-1 for NPK. Moreover, these treatments increased the P sorption saturation to 33 % and 37 %, respectively, as compared to 12 % for NPK, and significantly enhanced P desorption, raising concerns about eutrophication. A path analysis was carried out to elucidate the effects of P dosage, liming, and manuring on soil properties, available P, P adsorption-desorption parameters, yield, and P uptake. In summary, the NPK+Lime treatment offered the most balanced approach, improving both crop yield and P uptake while effectively managing P dynamics in the soil. On the contrary, long-term application of NPK+FYM in an acid soil may result in faster P saturation of adsorption sites and increase the chances of leaching and eutrophication. Furthermore, tailored P fertilization strategies should be developed to better utilize the P Fe and P Al fractions and supplementing applied P.
Aims: The cattle manure application to subsoil is an efficient and sustainable approach to increase soil fertility. However, the change of soil organic carbon (SOC) chemistry after manure amended in subsoil is remains elusive.
Methods: Here, a pot experiment was used to investigated the SOC chemical structure (¹³C-NMR and FTIR), as well as microbial community composition (PLFA), with cattle manure amended in topsoil (T1M), and subsoil (T2M) and without manure in topsoil (T1) and subsoil (T2).
Results: The utilization of cattle manure significantly improved SOC, total nitrogen (TN) content and PLFAs biomass, as well as the relative absorption of the band at 2920 cm-1 and 1640 cm⁻¹ of SOC, while decreased the C/N ratio by 15.7-50.5%. T1M increased the proporations of O-alkyl C and Aromatic C by 3.8%-17.6% compared to T1, but decreased the proporations of Alkyl C and Carbonyl C by 9.9%-11.5% and the ratio of Alkyl C/O-Alkyl C (A/OA) by 60.0%. However, T2M showed the opposited trend compared to T2. The fungal to bacterial ratio (F/B) of T2 was lower than that of T1, while it was greater in T2M than that in T1M. Both RDA and MRT analyses demonstrated that the Cyanobacteria, Acidobacteria and Ascomycota were negatively association with O-alkyl C, and the Actinobacteria, Verrucomicrobia and Cyanobacteria were negatively association with Alkyl C.
Conclusions: Our findings reveal application cattle manure in subsoil was more beneficial to decompose SOC owing the transfromation of bacterial to fungal and made the chemical structure of SOC more stabilization.
This study was conducted in a temperate mixed oak-pine forest of Central Himalaya, India to i) evaluate altitudinal and seasonal variations in the microbial biomass carbon (C), nitrogen (N) and phosphorus (P) and (ii) analyse the relationships between soil microbial biomass C, N and P and physico-chemical properties of soil. Three permanent plots were established in natural forest stands along an altitudinal gradient, three replicates were collected seasonally from each site, and microbial biomass (C, N and P) were determined by a fumigation extraction method. Microbial biomass C, N and P decreased significantly (p < 0.01, correlation coefficient 0.985, 0.963, 0.948, respectively) with increasing altitude having maximum values during rainy season and minimum values during winter season. Microbial biomass C, N and P showed positive correlations with silt particles, water holding capacity, bulk density, soil moisture, organic C, total N and P and negative correlations with sand particles, porosity and soil pH. Microbial biomass C was strongly associated with soil microbial N (r = 0.80, p < 0.01) and P (r = 0.89, p < 0.01) content and soil microbial biomass N and P also showed a strong linear relationship (r = 0.92, p < 0.01). Soil microbial biomass exhibited weak seasonality and was highly influenced by altitude and abiotic variables. The significantly high microbial C, N and P during the rainy season (p < 0.01) and low microbial biomass during the winter season may be due to higher immobilization of nutrients from decomposing litter by microbes as the decomposition rate of litter and microbial activity are at their peak during the rainy period. The microbial C:N ratio indicated that soil fertility is influenced by species composition. Our findings suggested that high microbial biomass and low C:N ratios during the rainy season could be considered a nutrient conservation strategy of temperate mixed oak-pine forest ecosystems .
The concept of soil health has gained importance recently, recognizing the soil as a living entity. In the recent scenario of urbanization and excessive land use, agricultural land is subjected to degradation and desertification. For sustainable agriculture production and ecological interactions, there is a dire need for management strategies to improve soil health and quality. Mulching is among the important conservation strategies to enhance soil health by improving soil biota, organic contents, and soil aggregation. In this chapter, we encompassed the different categories of living entities dwelling in soil and their key activities to enhance ecological relations of soil. Based on the literature study, mulches are proved to be very efficient in improving soil biota, soil moisture retention, maintaining the soil temperature, nutrient dynamics, decrease in severity of soil contaminants, suppression of weeds, and control in insects pests. The addition of mulch in the soil fluctuate a number of indicators of soil biota, which account for soil health. Species diversity, microbial biomass, soil respiration, organic content, and enzymatic respiration mainly determine quality status of soil biota, which are influenced by mulches. We have also given the overview of indices of species diversity, i.e., richness, evenness, and phylogenetic indices altered by the introduction of mulches in soil and thus modify the ratio of pests predators. Moreover, based on field conditions, crop and mulch type, and environment-specific application of mulch can become more productive for soil conservation, plant growth and soil biota.
Manure amendments are a common soil amendment in forage and row cropping systems used to provide plant-available nutrients, build soil organic matter, and enhance soil health. Many of the benefits of manure applications are thought to be driven via their impacts on soil microbial communities. However, manure amendments may also introduce potential undesirable microbes (pathogens, or those with antibiotic resistance elements) to soils. Despite the widespread use of manure amendments and their importance in agricultural systems, the forces governing the assembly of bacterial communities in soil in response to manure amendments are poorly characterized, limiting our ability to predict their impacts on soil communities. We constructed soil microcosms using five soils from different locations to investigate the impacts of liquid dairy manure on bacterial communities. Moreover, we used combinations of autoclaved liquid dairy manure and soils to determine the roles of abiotic and biotic factors in the response of indigenous soil communities to manure and the fate of manure-borne bacteria. Bacterial amplicon sequence variants (ASVs) that responded to manure amendment were largely dependent on soil origin. Initial shifts in soil communities after manure amendment were driven by the introduction of manure-borne taxa. However, introduced taxa died off rapidly while some indigenous taxa increased in relative abundance over time. Introduced taxa died off even in the absence of indigenous microbiota, suggesting that the soil abiotic environment is a strong barrier to colonization by manure-borne bacteria. Finally, autoclaved manure amended to soil elicited a similar response from indigenous soil microbes as did live manure, indicating that organic matter, nutrients, or other physiochemical factors associated with manure amendments are responsible for changes in indigenous soil populations.
Human activities have caused an increase in greenhouse gas emissions, resulting
in climate change that affects many factors of human life including its effect
on water and food quality in certain areas with implications for human health.
CH4 and N2O are known as potent non-CO2
GHGs. The livestock industry contributes to direct emissions of CH4
(38.24%) and N2O (6.70%) through enteric fermentation and manure
treatment, as well as indirect N2O emissions via NH3
volatilization. NH3 is also a secondary precursor of particulate
matter. Several approaches have been proposed to address this issue, including
dietary management, manure treatment, and the possibility of inhibitor usage.
Inhibitors, including urease and nitrification inhibitors, are widely used in
agricultural fields. The use of urease and nitrification inhibitors is known to
be effective in reducing nitrogen loss from agricultural soil in the form of
NH3 and N2O and can further reduce CH4 as a
side effect. However, the effectiveness of inhibitors in livestock manure
systems has not yet been explored. This review discusses the potential of
inhibitor usage, specifically of N-(n-butyl) thiophosphoric triamide,
dicyandiamide, and 3,4-dimethylpyrazole phosphate, to reduce emissions from
livestock manure. This review focuses on the application of inhibitors to
manure, as well as the association of these inhibitors with health, toxicity,
and economic benefits.
This study aimed to investigate the effect of different farming practices (conventional vs. organic farming) and crops on soil microbial biomass and microbial community structure based on signature phospholipid fatty acid (PLFA). Randomized complete block design with three blocks/site and factorial treatment combination of 4 crops (chickpea, mustard, soybean, and maize) × 2 farming practices (24 blocks) was applied. Soils samples were analyzed for soil biological characteristics including, microbial biomass (C and N) and microbial profile (lipid biomarker-based) in triplicate. Organic farming practices significantly elevated the soil total organic C (TOC), total N (TN), and microbial biomass C (MBC) and N (MBN). Total phospholipid fatty acid contents increased significantly under organic management. Bacterial PLFA with G + bacteria dominated the scenario under both the treatments with the highest value under organic farming. The fungal: bacterial ratio showed positive variation with conventional to organic fertilizer treatments suggesting a shift in the microbial community. A significant effect (p < 0.05) of the crop was observed with the highest total PLFA content/microbial biomass in maize and lowest in soybean cultivated soil. The PCA analysis, where two principal components explained 92.38% variation, represented most of the PLFA biomarkers towards organic farming. This study shows that total microbial community composition responds actively to crop and farming practices. Organic farming emerged as an effective management practice because of its potential to improve soil biological properties and thus a sustained crop yield. Among crops, maize showed the highest total PLFAs in both the farming practices while lowest in the soybean.
Irrigation enhances the connectivity between the surface and groundwater by facilitating the transport of energy sources and oxygen. When combined with fertilisers, the impact on groundwater microbial communities and their interactions with nitrogen cycling in aquifers is poorly understood. This study examines the impact of different landuses (irrigated and non-irrigated) on groundwater microbial communities. A total of 38 wells accessing shallow aquifers in three sub-catchments of the Murray Darling Basin, Australia, were sampled for water chemistry and microbial community structure using environmental DNA (eDNA) techniques. All sub-catchments showed evidence of intense irrigation and groundwater contamination with total nitrogen, nitrates and phosphorus concentrations often well above background, with total nitrogen concentrations up to 70 mg/L and nitrate concentration up to 18 mg/L. Across sub-catchments there was high microbial diversity, with differences in community structure and function between catchments and landuses. Of the 1100 operational taxonomic units (OTUs) recorded, 47 OTUs were common across catchments with species from Woesearchaeota, Nitrospirales, Nitrosopumilales and Acidobacter taxonomic groups contributing greatly to groundwater microbial communities. Within non-irrigated sites, groundwaters contained similar proportions of nitrifying and denitrifying capable taxa, whereas irrigated sites had significantly higher abundances of microbes with nitrifying rather than denitrifying capabilities. Microbial diversity was lower in irrigated sites in the Macquarie catchment. These results indicate that irrigated landuses impact microbial community structure and diversity within groundwaters and suggest that the ratios of denitrifying to nitrifying capable microbes as well as specific orders (e.g., Nitrososphaerales) may be useful to indicate long-term nitrogen contamination of groundwaters. Such research is important for understanding the biogeochemical processes that are key predictors of redox state and contamination of groundwater by N species and other compounds. This will help to predict human impacts on groundwater microbial structure, diversity, and ecosystem functions, aiding the long-term management groundwater resources.
Nitrogen (N) fertilizer management in agricultural field affects soil N budget that can have significant implication in greenhouse gas emission and environmental pollution. This study investigates the effects of nitrification inhibitors Dicyandiamide (DCD) and 3,4-dimethyl pyrazole phosphate (DMPP) with urea application on soil N budget and microbial community in a subtropical pasture field. A field experiment consisting of four treatments, including control, urea, urea DCD, and urea DMPP was conducted in 2016 and 2017. Nitrous oxide emission and inorganic-N losses through leaching and runoff were quantified. In addition, soil microbial community response to the imposed treatments was characterized by analysis of phospholipid fatty acid (PLFA). The results showed that DCD and DMPP applications significantly reduced fertilizer-induced N2O emission by over 76% and 67%, respectively. Although nitrification inhibitors’ (NIs) applications greatly reduced NO3– in runoff and leaching, there was no significant impact of either NI on pasture biomass yields. Comparing to the plant N uptake, N loss through N2O emission, runoff, and leaching were small in pasture. The low N losses would indicate that NI’s potential to increase yield is small. Addition of 10 kg DCD ha⁻¹ and 1 kg DMPP ha⁻¹ reduced the negative effect induced by urea on total microbial PLFA, and benefited fungi, bacteria, and actinomycetes in short-term. Overall, the results demonstrate the positive effects of NIs on greenhouse gas reduction, water quality, and improving soil health through enhancing total microbial activity and reducing microbial environmental stress.
The ecological distribution and activities of soil microbes can reflect the influence of environmental factors on microbes and changes in soil fertility. Understanding the community structure of the soil microbes is of great importance to maintaining soil health in ancient mulberry plantation ecosystems. In this study, the population structure of soil microorganisms in different ages of mulberry plantations was analyzed using high-throughput sequencing technology. A total of 1616, 1568, 1379 and 1477 operational taxonomic units were acquired from samples of 3Y (3-year-old), 35Y (35-year-old), 200Y (200-year-old) and 600Y (600-year-old) soils, respectively. The results exhibited that the highest community diversity was found in 35Y soil, followed by 200Y soil, and showed that the stand age strongly influenced the community structure of soil bacteria. A total of 23 phyla were detected in 12 samples, and the genus of bacteria that predominated the different stand ages mainly included; Phenylobacterium, Cohnella, Lactococcus, Sphingomonas, Bacillus, and Microbispora. The relative abundance of Phenylobacterium accounts for 22.6–53.5% of the total abundance. This study showed that the richness and diversity of the soil bacteria decreased as the stand age increased in ancient mulberry plantations.
Utilization of organic matter as a chief substrate for agricultural crops and beneficial microorganisms is gaining interest of plant pathologists, agronomists, manufacturing and processing industries, regulators, growers, tycoons and consumers. These organic inputs provide energy and nutrients to soil leading to a considerable change in the environment which becomes appropriate for survival of crops and proliferation of microorganisms. More likely, this exercise is further reinforced by the consumers’ demand as they are more conscious towards their health. Moreover, use of organic matter rather than disposal is preferred because it imparts in the market value and recycles back to the land leading towards the enhanced sustainable agricultural system. Various types of organic materials are now available and growers have been familiar with these wastes. However, efficacious nature of each organic matter is different maybe partly due to their chemical constituents, types, origin and duration of decomposition. Henceforth, the results of these natural products are inconsistent from site to site as well as from field to field. Similarly, there is no single mechanism which can advocate the queries prudently pertaining to disease management caused by various soilborne plant pathogens. Some common instances have, however, been exemplified like secretion of pathogen toxic compounds, alteration in soil physico-chemical properties, enhanced microbial activities and induction of host resistance against wide spectrum of soilborne pathogens. Moreover, soil is indistinct part of the ecosystem which may regulate the plants response. Application of low rate of organics is suggested as this will be affordable to the growers. In our opinion, this may be possible through appropriate site selection, formulation, storage and handling as well as consortia of organic matter with other compatible modules. Major problem in the adoption of this technology is insufficient supply of ready-made organics which needs a prudent optimization in order to attain sustainable agriculture.
Interactions between bacteria and protozoa in soil were studied over 2-week periods in the field and in a pot experiment. Under natural conditions the total biological activity was temporarily synchronized by a large rainfall, and in the laboratory by the addition of water to dried-out soil, with or without plants. In the field, peaks in numbers and biomass of bacteria appeared after the rain, and a peak of naked amoebae quickly followed. Of the three investigated groups-flagellates, ciliates, and amoebae-only populations of the latter were large enough and fluctuated in a way that indicated a role as bacterial regulators. The bacterial increase was transient, and the amoebae alone were calculated to be able to cause 60% of the bacterial decrease. The same development of bacteria and protozoa was observed in the pot experiment: in the presence of roots, amoebic numbers increased 20 times and became 5 times higher than in the unplanted soil. In the planted pots, the amoebic increase was large enough to cause the whole bacterial decrease observed; but in the unplanted soil, consumption by the amoebae caused only one-third of the bacterial decrease.
An uncontaminated subsurface aquifer sediment contains a sparse microbial community consisting primarily of coccobacillary bacteria of relatively uniform size which can be counted directly with appropriate staining. The morphological simplicity and the relatively decreased cell numbers, when compared with surface soils and sediments, make the subsurface an ideal natural community with which to compare the utility of chemical measures of microbial biomass to direct microscopic counts. The membrane phospholipids (estimated as the polar lipid fatty acids, the lipid phosphate, and phosopholipid glycerol phosphate), lipopolysaccharide lipid A (estimated as the LPS hydroxy fatty acids), cell walls (estimated as the muramic acid), and adenosine triphosphate all give essentially identical estimates of cell numbers and dry weight as the direct counts, using conversion factors determined on subsurface microorganism monocultures. Assays of microbial cell components are thus validated by comparison with the classical direct count in at least one soil/sediment.
Soil samples taken from four experimental sites that had been cropped to continuous corn for 3–11 years in Ontario and Quebec
were analyzed to evaluate changes in quantity and quality of labile soil organic carbon under different nitrogen (N) fertility
and tillage treatments. Addition of fertilizer N above soil test recommendations tended to decrease amounts of water-soluble
organic carbon (WSOC) and microbial biomass carbon (MBC). The quality of the WSOC was characterized by 13C nuclear magnetic resonance and infrared spectrophotometry and the results indicated that carbohydrates, long-chain aliphatics
and proteins were the major components of all extracts. Similar types of C were present in all of the soils, but an influence
of management was evident. The quantity of soil MBC was positively related to the quantities of WSOC, carbohydrate C, and
organic C, and negatively related to quantities of long-chain aliphatic C in the soil. The quantity of WSOC was positively
related to the quantities of protein C, carbohydrate C, and negatively related to the quantity of carboxylic C. The quantity
of soil MBC was not only related to quantities of soil WSOC but also to the quality of soil WSOC.
More than 19 million Mg of dairy manure are produced annually in the Canadian provinces of Quebec and Ontario, and most of it is spread on agricultural fields. Quantitative information on the impact of manure management practices on levels of soluble organic carbon (SOC) and emissions of CO 2 is important for assessing whether this management significantly contributes to increasing atmospheric CO 2 concentrations. The objective of this study was to measure the effects of dairy cattle manure (applied at 0, 56, and 112 Mg ha -1) on SOC levels in, and soil surface CO 2 fluxes from, a typical maize (Zea mays L.) field in central Canada, from April to October. The higher rate of manure increased both the CO 2 emissions and the SOC levels by a factor of two to three compared with the control. Fluxes of CO 2 were very low immediately after thaw, increased sharply following manure application and increased again in mid-June at the time when temperature and sort moisture increased; thereafter, fluxes declined throughout the rest of the season. Over the season, which was drier than normal, SOC was not a good predictor of CO 2 flux. Carbon dioxide flux increased proportionately less for the second 56 Mg ha -1 increment of manure added than for the first increment. Factors other than the quantity of SOC limited soil respiration at the highest manure application rate. Carbon dioxide is contributed to the atmosphere at a lower rate, and proportionately more manure C is retained in soil with increasing levels of manure applied.
A polyphasic approach to bacterial taxonomy attempts to integrate phylogenetic relationships with phenotypic marker analysis. This study describes the application of membrane fatty acids as a phenotypic marker for methylotrophs. Detailed phospholipid, ester-linked fatty acid (PLFA) profiles are reported for 17 methylotrophic eubacterial strains. These profiles included verification of double bond positions and geometries, both critical features for this analysis. Multivariate cluster analysis was used to indicate groupings of these strains along with literature values of both methylotrophs and non-methylotrophs based on the PLFA phenotype. Like many phenotypic characteristics, PLFA profiles were influenced by environmental conditions. The instabilities displayed, however, were predictable from physiological studies including increased trans/cis and cyclopropyl/cis ratios. Cluster analysis of PLFA profiles generated by separate investigators with different culture conditions indicated reproducibility by strain and species. The PLFA phenotype relationships compare favourably with phylogenetic associations based on 16S rRNA data for methylotrophs and will continue to be a valuable phenotypic marker for Proteobacteria taxonomy.
Microbial community dynamics associated with manure hot spots were studied by using a model system consisting of a gel-stabilized mixture of soil and manure, placed between layers of soil, during a 3-week incubation period. The microbial biomass, measured as the total amount of phospholipid fatty acids (PLFA), had doubled within a 2-mm distance from the soil-manure interface after 3 days. Principal-component analyses demonstrated that this increase was accompanied by reproducible changes in the composition of PLFA, indicating changes in the microbial community structure. The effect of the manure was strongest in the 2-mm-thick soil layer closest to the interface, in which the PLFA composition was statistically significantly different (P < 0.05) from that of the unaffected soil layers throughout the incubation period. An effect was also observed in the soil layer 2 to 4 mm from the interface. The changes in microbial biomass and community structure were mainly attributed to the diffusion of dissolved organic carbon from the manure. During the initial period of microbial growth, PLFA, which were already more abundant in the manure than in the soil, increased in the manure core and in the 2-mm soil layer closest to the interface. After day 3, the PLFA composition of these layers gradually became more similar to that of the soil. The dynamics of individual PLFA suggested that both taxonomic and physiological changes occurred during growth. Examples of the latter were decreases in the ratios of 16:1 omega 7t to 16:1 omega 7c and of cyclopropyl fatty acids to their respective precursors, indicating a more active bacterial community. An inverse relationship between bacterial PLFA and the eucaryotic 20:4 PLFA (arachidonic acid) suggested that grazing was important.
The phospholipid fatty acid (PLFA) pattern was analyzed in a forest humus and in an arable soil experimentally polluted with Cd, Cu, Ni, Pb, or Zn at different concentrations. In both soil types, there were gradual changes in the PLFA patterns for the different levels of metal contamination. The changes in the forest soil were similar irrespective of which metal was used, while in the arable soil the changes due to Cu contamination differed from those due to the other metals. Several PLFAs reacted similarly to the metal amendments in the two soil types, while others showed different responses. In both soils, the metal pollution resulted in a decrease in the iso-branched PLFAs i15:0 and i17:0 and in the monounsaturated 16:1omega5 and 16:1omega7c fatty acids, while increases were found for i16:0, the branched br17:0 and br18:0, and the cyclopropane cy17:0 fatty acids. In the forest soil, the methyl branched PLFAs 10Me16:0, 10Me17:0, and 10Me18:0 increased in metal-polluted soils, indicating an increase in actinomycetes, while in the arable soil a decrease was found for 10Me16:0 and 10Me18:0 in response to most metals. The bacterial PLFAs 15:0 and 17:0 increased in all metal-contaminated samples in the arable soil, while they were unaffected in the forest soil. Fatty acid 18:2omega6, which is considered to be predominantly of fungal origin, increased in the arable soil, except in the Cu-amended samples, in which it decreased instead. Effects on the PLFA patterns were found at levels of metal contamination similar to or lower than those at which effects on ATP content, soil respiration, or total amount of PLFAs had occurred.
The ecosystem ecologist and the population ecologist often set out to describe the structure and function of an ecosystem or of a population. The biotic structure is given by a description of the species present and their abundance, while the function of the biotic component of the ecosystem calls for a fairly detailed analysis of the role of individual populations (species or functional groups) in, for example, energy flow or nutrient cycling.
Cover cropping impacts soil properties in many positive ways. These include higher total carbon, which usually contributes to increased cation exchange capacity and water-holding capacity. Enhanced soil physical and chemical properties result in a better environment for the activity of soil microorganisms. We conducted a study of biological properties in no-till corn plots receiving either 0 or 168 kg N ha -1. Plots were planted in the fall each year with a hairy vetch (Vicia villosa Roth), winter wheat (Triticum aestivum L.), or no cover crop. The vetch cover resulted in the highest organic C accumulations, and the addition of N to the wheat or no cover plots increased C relative to the no N treatments. Soil organic C was not different between the vetch with and without N, but pH was significantly reduced by N fertilization. Hairy vetch had a greater effect on microbial numbers than did the wheat cover or no cover. The greatest bacterial numbers were observed in the vetch with no N treatment. Acid phosphatase, arylsulfatase, β-glucosidase and L-asparaginase activities were all higher in the vetch with no N treatment than any of the other combinations. In the wheat and no cover treatments, the enzyme activities mentioned earlier were all higher in the 168 kg N treatments. Soil treatments that increased soil organic C enhanced the activity of soil microorganisms and/or provided a better environment for the stabilization of microbially produced soil enzymes. Our data indicated that the use of cover crops significantly enhanced soil biological properties as measured by microbial numbers and enzyme activities. The use of cover crops provides soil quality benefits in addition to the reduction in soil loss attained with these systems.
A field was artificially eroded by levelling in 1957. Continuous cropping to barley for 7yr followed a wheat-fallow rotation for 14yr without nutrient application did not significantly improve the soil productivity of severely "eroded' land. Manure and commercial fertilizer treatments essentially restored productivity within the first year, as measured by wheat yields, regardless of severity of erosion. During years of drought stress which often occur under dryland conditions, the manure application on the "eroded' soil treatments resulted in yields greater than those on check or fertilized plots. -from Authors
The physical, chemical, and biological soil environment for reduced or no‐till farming differs greatly from that for conventional tillage. Evaluation of the soil microbial and biochemical environment greatly aids predictions of N availability to crop plants and in optimizing management practices for reduced and no‐till soils.
Surface soils from long‐term no‐till and conventional tillage plots at seven U.S. locations were characterized for microbial and biochemical components. The counts of aerobic micro‐organisms, facultative anaerobes, and denitrifiers in the surface (0–7.5 cm) of no‐till soils were 1.14 to 1.58, 1.57, and 7.31 times higher, respectively, than in the surface of plowed soil. Phosphatase and dehydrogenase enzyme activities and contents of water and organic C and N in the surface of no‐till soil were also significantly higher than those for conventional tillage. However, at the 7.5‐ to 15‐cm and 15‐ to 30‐cm depths these trends were reversed and microbial populations, enzyme activities, and water and organic C and N contents were the same or higher for conventional tillage than for no‐till. The trends in microbial populations with both tillage treatments were closely paralleled by soil enzyme activities and were also regulated by soil pH and levels of organic C and N. The surface 0‐ to 7.5‐cm of no‐till soil contained more potentially mineralizable N—20 to 101 kg/ha—than did that of plowed soils. This increased labile N reserve is apparently related to the higher microbial biomass present under no‐till soils.
Maximum aerobic microbial activity with conventional tillage extends to a greater depth than with no‐till. Microbial populations under no‐till decrease rapidly below the 7.5‐cm depth. At the 7.5‐ to 15‐cm depth counts of aerobic microor‐ganisms and nitrifiers were 1.32 to 1.82 times higher on the conventionally tilled soils. However, counts for facultative anaerobes and denitrifiers were 1.23 to 1.77 times higher for no‐till soil. Also, the proportion of the total aerobic population represented by facultative anaerobes and denitrifiers for no‐till was twice that for conventional tillage. Consequently the potential rate of mineralization and nitrification is higher with conventional tillage while that for denitrification is higher with no‐till.
Microbial population counts and the relative abundance of various microbial types suggests that the bochemical environment of no‐till soils is less oxidative than that under conventional tillage. Changes in tillage and fertilizer management practices required for no‐till soils should reflect the increased potential for immobilization of surface applied N and the lower levels of plant available NO 3 ‐ as compared with those under conventional tillage.
Carbon and nitrogen (N) content of various soils in the world were analyzed using a CNS‐2000 (LECO, Corp., St. Joseph, MI) analyzer. The results were in good agreement with those obtained by a laboratory proficiency test at the International Soil‐Analytical Exchange, organized by Wageningen Agricultural University, Wageningen, The Netherlands. The best agreement for both elements was observed at a combustion temperature of 1000°C. Results of organic carbon (C) determined by the Tyurin method were closely related to results of C determination at this temperature. Higher C contents were obtained with samples rich in carbonates when analyzed at higher temperatures >1000°C. These results confirm the suitability of automated dry combustion in soil analysis for C and N.
A long-term field experiment was set up in 1981 in north-eastern Victoria to determine the effects of conservation tillage farming on agronomic and soil properties. Conventional cultivation was compared with direct drilling, and stubbles retained from the previous crop were compared with burning under direct drilling. Wheat was grown continuously over the 7 years of the experiment. Organic carbon (C), total nitrogen (N), soil microbial biomass and earthworm populations were measured. When samples were taken incrementally down the soil profile, there was a significant concentration gradient of organic matter under direct drilling. In the surface 2.5 cm, biomass C and N, and N mineralisation were 35, 30 and 62% greater, respectively, than under conventional cultivation. Direct drilling into retained stubble did not significantly increase organic C or total N. Of the estimated 7.8 t C/ha added to the soil from conserved crop stubbles, 4% was retained in the top 7.5 cm at the time of sampling. Organic C, total N and biomass C and N decreased with depth in both treatments. Microbial biomass varied considerably with season. The biomass of earthworms in the top 10 cm, under direct drilling, was more than twice that of conventional cultivation, while total worm numbers increased significantly (P<0.05), from 123 to 275/m2, when wheat stubble was retained with direct drilling compared to stubble burning.
This study, conducted in the Piedmont of North Carolina, was initiated to determine how reductions in N fertilization and green‐manuring with crimson clover ( Trifolium incarnatum L. cv. Tibbee) would affect populations and activities of soil microorganisms. Four continuous corn ( Zea mays L.) treatments were used: no‐till (receiving herbicides and soil insecticides) with 0 or 140 kg N ha ⁻¹ as NH 4 NO 3 ; conventionally tilled, receiving 140 kg N ha ⁻¹ , but no pesticides; and conventionally tilled with a crimson clover green manure, but no fertilizer or pesticides. Populations were determined using selective media for culturable bacteria, gram‐negative bacteria, fungi, actinomycetes, Bacillus spp., and Pseudomonas spp. Microbial activities were estimated by enzyme assays for acid and alkaline phosphatase, arylsulfatase, and β‐glucosidase. Microbial biomass C was determined by a chloroform fumigation‐extraction procedure and levels of available N were measured after anaerobic incubation. Surface soil (0–7.5 cm) from the no‐till treatment receiving 140 kg N ha ⁻¹ contained significantly more fungi than did soil from the unfertilized, no‐till treatment. Microbial biomass C and available N were not affected by N addition, but levels of acid phosphatase and β‐glucosidase were significantly higher in the fertilized soil than in the unfertilized soil. Surface soil from a crimson clover‐corn rotation contained significantly larger populations of Bacillus spp. (260% more), actinomycetes (310% more), and culturable bacteria (120% more) than did soil from the well‐fertilized conventionally tilled, no‐pesticide treatment. Also, microbial biomass, available N, and levels of alkaline phosphatase, arylsulfatase, and β‐glucosidase were significantly higher in surface soil from the crimson clover treatment than the nonmanured soil. Although the soil biological properties changed significantly during the year, seasonal variations were similar across treatments. Microbial numbers and activities were high in the spring and fall and low during the late summer.
There is evidence from laboratory incubations that denitrifying bacteria occur in the deep subsoils of UK soils and that lack of available carbon (C) generally limits their activity. Animal manures can be a source of substantial carbon input to farming systems. This experiment measured the effect of broiler litter application on the movement of C in soil solution to depths below 1 m, which might be sufficient to allow denitrification of nitrate moving from the rooting zone towards ground water aquifers. Six broiler litter rates were applied each autumn from 1992–1994 to field plots on a loamy medium sand in Nottinghamshire, UK. Total loadings over the 3 years ranged from 0 to 125 t ha-1 broiler litter, supplying 0–32 t ha-1 total C. Teflon and ceramic water samplers, placed at 1·0 and 1·5 m, and monolith lysimeters (0·5 m2 area, 1·5 m deep) were used to measure total organic carbon (TOC) concentrations in the drainage. Ceramic samplers indicated significantly (P<0·05) larger concentrations than Teflon samplers; there were no differences between concentrations measured by Teflon samplers and the lysimeters. Water samples analysed for both dissolved and total C showed that nearly all was in a dissolved form. TOC concentrations on plots which received no manure were less than 20 mg litre-1 at 1 m for the duration of the experiment; concentrations peaked at 65 mg litre-1 with the largest manure loading. There was a linear relationship between C leached and C applied, with about 5% leached below 1 m by the end of the experiment. There was some evidence of movement of C to 1·5 m depth, but there were no large peaks corresponding to those at 1 m, because of either adsorption or microbial utilisation. The results provide evidence of movement of substantial C to depth in some circumstances, particularly on fields which regularly receive large dressings of organic manure. The availability of this as a substrate for denitrification needs further examination. © 1997 SCI
Thirty closely spaced cores were obtained from Miocene-aged fluvial, lacustrine and palaeosol subsurface sediments ranging in depth from 173 to 197 m at a site in south-central Washington to investigate the size and composition of the microbial community in relation to sediment geochemical and geophysical properties. Total phospholipid fatty acid (PLFA) analysis indicated that the greatest concentrations of microbial bio-mass were in low-permeability lacustrine sediments that also contained high concentrations of organic carbon. Community structure, based on lipid analyses and on in situ hybridization of bacterial cells with 16S RNA-directed DNA probes, also revealed the presence of metabolically active bacteria that respire sulphate and/or Fe(III) in the lacustrine sediments. Concentrations of pore water sulphate were low (4–8 mg/L) and HCI-extractable Fe was predominantly Fe(II) in the same samples where total biomass and organic carbon were highest. The low hydraulic conductivity (10-6 to < 10-9 cm/s) of these sediments has likely contributed to the long term maintenance of both bacteria and organic carbon by limiting the supply of soluble electron acceptors for microbial respiration. These results suggest that the current subsurface microbial population was derived from organisms that were present during lake sedimentation = 6–8 million years ago.
Abstract Phospholipid fatty acid (PLFA) profiles provide a robust measure that can be used to fingerprint the structure of soil microbial communities, and measure their biomass. A replicated field trial, with gradients in substrate and O2 availability created by straw incorporation and flooding was used to test the ability of PLFA to discriminate soil microbial communities in different management regimes. Another objective was to test the usefulness, on a large scale, of some of the proposed interpretations of PLFA biomarkers. Using a direct gradient statistical analysis method, PLFA profiles were found to be very sensitive to flooding and straw treatments. Relative abundances of monounsaturated fatty acids were reduced with flooding and increased with added carbon, consistent with their proposed interpretations as indicators of aerobic conditions and high substrate availability. The cyclopropyl fatty acids were not useful as taxonomic indicators of respiratory type, although their responses were consistent with their proposed use as growth condition indicators. Branched fatty acids decreased, as a group, in response to high substrate conditions. A specific biomarker for Type II methanotrophs was not found in this rice soil, even under high carbon, low O2 conditions, which resulted in methane exposure in the soil. Direct comparison of PLFA and substrate utilization patterns indicated that Biolog patterns are highly selective, and do not reflect compositional changes in soil communities.
Temporal behaviour of microbial biomass C, N and respiration was measured under barley crops in two experiments on successive
years in a recently converted organic production system in Scotland. Soils were fertilised with farmyard manure or poultry
manure. Control soils received no manure at the start of the growing season. The effects of plants was also investigated by
maintaining fallow subplots. C-flush values approximately doubled over the growing season in both years of the trial, showing
a decline to pre-sowing values between the two seasons. This occurred in all soils, whether manured or not, or planted or
fallow. Manure tended to increase the C-flush in the 2nd year only. N-flush in the 2nd year showed no increase in planted
control plots but did increase in fallow soils. Manures significantly increased the N-flush. Respiration rates were stimulated
by the presence of plants. Respiration rates were measured from soils taken from the field at post-sowing, mid-season and
post-harvest occasions and incubated under constant conditions for up to 1 year. Here there was evidence that the effects
of sampling and adjusting the moisture status could be as great upon microbial activity as the addition of the manures. C-flush
also showed a consistent and persistent increase in these incubated soils. This suggests that the fundamental C-supplying
characteristics of these soils was such that the biomass was moving towards a new equilibrium value fuelled by the relatively
recent introduction of the organic farming regime.
Humus phospholipid fatty acid (PLFA) analysis was used in clear-cut, wood-ash fertilized (amounts applied: 1000, 2500, and 5000 kg ha−1), or prescribed burned (both in standing and clear-cut) coniferous forests to study the effects of treatments on microbial biomass and community structure. The microbial biomass (total PLFAs) decreased significantly due to the highest rate of wood-ash fertilization, clear-cutting, and the two different fire treatments when compared to control amounts. Fungi appeared more seriously reduced by these treatments than bacteria, as revealed by a decreased index of fungal:bacterial PLFAs when compared to the controls. The community structure was evaluated using the PLFA pattern. The largest treatment effect was due to burning in both areas studied, which resulted in increases in 16:1ω5 and proportional decreases in 18:2ω6. Clear-cutting and the different amounts of ash application resulted in similar changes in the PLFA pattern to the burning treatments, but these were less pronounced. Attempts to correlate the changes in the PLFA pattern to soil pH, bacterial pH response patterns (measured using thymidine incorporation), or substrate quality (measured using IR spectroscopy) were only partly successful. Instead, we hypothesize that the changes in the PLFA pattern of the soil organisms were related to an altered substrate quantity, that is the availability of substrates after the treatments.
Analysis of phospholipids extracted from various moss and sedge peat types revealed significant differences in the patterns of the phospholipid fatty acids (PLFA) with respect to the major botanical constituents of the peats. Principal component analysis of the PLFA data showed that peats dominated by Carex residues had higher relative amounts of cyclopropane fatty acids and cis vaccenic fatty acid (18:lω7c), but lower proportions of iso and anteiso methyl branched fatty acids compared to peat types dominated by Sphagnum residues. The data analysis also revealed a larger variation in the PLFA composition among the Sphagnum peats compared to the Carex types, which seems to relate to a larger variation in botanical composition among the Sphagnum than Carex peats. The differences in the fatty acid pattern indicate that the botanical composition influenced the bacterial community with Carex peats having a higher proportion of Gram-negative bacteria but lower proportion of Gram-positive bacteria compared to the Sphagnum peats. An exception was pure Sphagnum peats dominated by the subsection Acutifolia, where the bacterial community showed a closer similarity with the Carex peats. The ratios of trans to cis isomers of the unsaturated fatty acids 16:1 co 7 and 18:1 ω 7 were positively correlated with the degree of decomposition of the peat types, and may be an indication of increased starvation in the bacterial community as the decomposition proceeds.
The size of the soil microbial biomass was measured in a more than 30 yr old field experiment, whose treatments included different N fertilizers and organic manures. The size of the microbial biomass was measured as biomass C and N by the chloroform fumigation-incubation technique, as K2SO4 extractable ninhydrin-reactive N released upon fumigation and as the soil's ATP content. There was a high degree of correlation (r > 0.88) between the fumigation-based methods and the ATP determinations. Compared with the biomass estimate by ATP, biomass C was underestimated in the ammonium sulphate fertilized soil (pH 4.4), the peat-amended soils, and the sewage sludge amended soil. Biomass N was only underestimated in the ammonium sulphate and peat-amended soil, whereas there was a good correlation between the ninhydrin assay and the ATP assay for all soils. Between three successive years biomass C showed larger, statistically significant, variations than the size of the biomass measured by the ninhydrin assay.There was a high degree of correlation (r > 0.90) between both the rate of base respiration and the size of the microbial biomass and the soil's carbon content. These relationships generally held independent of whether carbon was derived from stabilized soil organic matter (in the fallow soil), from crop residues, or from organic manures such as straw, green manure, farmyard manure, or sawdust.Relative to the soil's carbon content the microbial biomass was smaller than expected in the peat amended-soils, the ammonium sulphate fertilized, and the sewage sludge-amended soil. The rate of base respiration was only lower than expected in the sewage sludge treated soil. The size of the biomass was negatively affected by a low soil pH, but the rate of base respiration was not. Liming some of the soils indicated that other factors than low pH restricted the size of the biomass in the peat and sewage-sludge amended soils, but not in the ammonium sulphate fertilized soils.
Variations in microbial population and nitrogen cycle microorganisms have been studied over one crop cycle in an acid Ranker over granite, under grass fertilized with cattle slurry and in the unfertilized soil. Cattle-slurry treatment brought about a great rise in total microbial population but affected different groups differently, though without changing the order of their population sizes. Bacteria were favoured, while the numbers of actinomycetes, fungi and algae were reduced, the latter especially. Slurry treatment increased the capacity for degradation and mineralization of nitrogen compounds by increasing the populations of proteolytics, ammonifiers and nitrifiers, though the latter group survived only briefly, their numbersfalling sharply again after a short time. The populations of denitrifiers and anaerobic free-nitrogen fixers also increased when slurry was applied, though much less strikingly than the groups mentioned above, whereas aerobic free-nitrogen fixers were depressed. Proteolytics, ammonifiers and denitrifiers were affected more by the first application of slurry than by the second, whereas the reverse was true of nitrifiers and anaerobic free-nitrogen fixers. All the groups studied except the algae tended to return to their initial population levels after some time.
Phospholipid, ester-linked fatty acid profiles showed changes in benthic prokaryotic community structure reflecting culture manipulations that were both quantitative and statistically significant. Fatty acid structures, including the position and cis/ trans geometry of double bonds, were chemically verified by GC/MS after appropriate derivatization. The fatty acid profiles of independent flasks showed reproducible shifts when manipulated identically and significant differences when manipulated with different treatments. The absence of polyunsaturated fatty acids indicated that the consortia were predominantly prokaryotic. The prokaryotic consortia of different treatments could be differentiated by the proportions of cyclopropyl fatty acids and the proportions and geometry of monounsaturated fatty acids.
To provide a procedure to estimate microbial biomass and community structure, an analytical method for the quantitative measurement of the profile of fatty acids derived from phospholipid (PL) and lipopolysacchride (LPS) in agricultural soil was developed and evaluated. The lipids were extracted by the one-phase procedure, and the PL was separated from other fractions by a solid phase column. Then, the PL was subjected to a mild alkaline hydrolysis to form fatty acid methyl esters (FAMEs). The hydroxy fatty acids methyl esters (OHFAMEs) derived from LPS in the soil studied were obtained by acidic hydrolysis of the extracted soil residue, followed by methylation. The FAMEs were further cleaned up and separated into several subgroups by utilization of consecutive solid phase columns. To measure the OHFAMEs and monoenoic FAMEs, these compounds needed further trimethylsilylization and dimethyl disulphide derivatization, respectively, before injection. Qualitative and quantitative measurements were made by an internal standard method using a GC-MS system. More than 160 fatty acids derived from PL and several dozens of hydroxy fatty acids derived from LPS in the soil have been found. The total amount of PL-FAs in the soil were found to be 23μg g−1. In contrast, the OHFAs derived from LPS amounted to only 519 ng g−1. As little as a few ng g−1 of these fatty acids present in the PL-fraction could be detected by this method. The recovery of bacterial standard FAMEs was between 73 and 104% after consecutive separation of FAMEs into various subgroups using solid phase columns. The diversity of the fatty acids may reflect the complexity of microorganisms present in the soil studied.
The active pool of organic matter plays an essential role in the short-term of nutrients turnover in soil. An approach to characterizing this fraction is through densimetric techniques which isolate soil light fractions. Cropping and tillage systems are determinants of the amount and distribution of soil organic matter, especially in the upper layers of the soil profile. Our objectives were to evaluate the distribution and dynamics of carbon in different density fractions in order to provide a better understanding of soil fertility changes induced by contrasting types of soil management: plow tillage, no-tillage and pasture. The total and active microbial biomass pools and microbial activity were also determined. The experiment was performed on a Typic Argiudoll from the Argentinean Pampa. Organic carbon was highest under pasture, but there were no differences between the others two treatments for the 0–15 cm layer. Under the pasture and no-tillage treatments, organic carbon decreased with depth. The light fraction (density ≤1.6 g ml−1) was higher under no-tillage than in the plowed soil, indicating that this fraction was more sensitive to management than was total carbon. The carbon mineralized in 160 d of incubation from different density fractions followed the order: light fraction>medium fraction (1.6–2 g ml−1)>heavy fraction (≥2 g ml−1), presumably because of an increase in chemical and physical protection of organic matter in the heavier fractions. Total soil microbial biomass was stratified under the pasture and no-tillage treatments. Basal respiration was significantly associated with the availability of carbon in the light fraction (r2=0.98, P<0.001) and carbon in the soil microbial biomass (r2=0.88, P<0.001). The active microbial biomass differed (P<0.05) between pasture (29 μg C g−1), no-tillage (19 μg C g−1) and plow tillage (9 μg C g−1). The active microbial biomass, as a fraction of the total soil microbial biomass, increased with depth in all treatments, but especially in plow tillage soils. There was a positive and strong association between the availability of carbon in the light fraction per unit of active soil microbial biomass and the ratio between the respiration in 10 d and the active microbial biomass (r2=0.93, P<0.001). Our results suggest that no-tillage produced the accumulation of carbon in the soil light fraction and increased the potential carbon mineralization. Consequently this tillage treatment can conserve the potential fertility of soil under cultivation.
A procedure for forming hierarchical groups of mutually exclusive subsets, each of which has members that are maximally similar with respect to specified characteristics, is suggested for use in large-scale (n > 100) studies when a precise optimal solution for a specified number of groups is not practical. Given n sets, this procedure permits their reduction to n − 1 mutually exclusive sets by considering the union of all possible n(n − 1)/2 pairs and selecting a union having a maximal value for the functional relation, or objective function, that reflects the criterion chosen by the investigator. By repeating this process until only one group remains, the complete hierarchical structure and a quantitative estimate of the loss associated with each stage in the grouping can be obtained. A general flowchart helpful in computer programming and a numerical example are included.
Lipid decomposition studies in frozen fish have led to the development of a simple and rapid method for the extraction and purification of lipids from biological materials. The entire procedure can be carried out in approximately 10 minutes; it is efficient, reproducible, and free from deleterious manipulations. The wet tissue is homogenized with a mixture of chloroform and methanol in such proportions that a miscible system is formed with the water in the tissue. Dilution with chloroform and water separates the homogenate into two layers, the chloroform layer containing all the lipids and the methanolic layer containing all the non-lipids. A purified lipid extract is obtained merely by isolating the chloroform layer. The method has been applied to fish muscle and may easily be adapted to use with other tissues.Lipid decomposition studies in frozen fish have led to the development of a simple and rapid method for the extraction and purification of lipids from biological materials. The entire procedure can be carried out in approximately 10 minutes; it is efficient, reproducible, and free from deleterious manipulations. The wet tissue is homogenized with a mixture of chloroform and methanol in such proportions that a miscible system is formed with the water in the tissue. Dilution with chloroform and water separates the homogenate into two layers, the chloroform layer containing all the lipids and the methanolic layer containing all the non-lipids. A purified lipid extract is obtained merely by isolating the chloroform layer. The method has been applied to fish muscle and may easily be adapted to use with other tissues.
Soil microbial popula-tions and activities in reduced chemical input agroecosystems Management-induced change in labile soil organic matter under continuous corn in eastern Canadian soils Determination of carbon and nitrogen in samples of various soils by dry combustion
- M J Kirchner
- A G Wollum
- L D King
- B C Liang
- A F Mackenzie
- M Schnitzer
- C M Monreal
- P R Voroney
- R P Beyaert
Kirchner, M.J., Wollum, A.G., King, L.D., 1993. Soil microbial popula-tions and activities in reduced chemical input agroecosystems. Soil Science Society of America Journal 57, 1289±1295. Liang, B.C., Mackenzie, A.F., Schnitzer, M., Monreal, C.M., Voroney, P.R., Beyaert, R.P., 1998. Management-induced change in labile soil organic matter under continuous corn in eastern Canadian soils. Biology and Fertility of Soils 26, 88±94. Matejovic, I., 1997. Determination of carbon and nitrogen in samples of various soils by dry combustion. Communications in Soil Science and Plant Analysis 28, 1499±1511.
Hierarchical grouping to optimize an objective function Biochemical measurements of microbial mass and activity from envir-onmental samples
- J H Ward
- ±
- D C White
- R J Bobbie
- J S Heron
- J D King
- S J Morrison
Ward, J.H., 1963. Hierarchical grouping to optimize an objective function. Journal of the American Statistical Association 58, 236±244. White, D.C., Bobbie, R.J., Heron, J.S., King, J.D., Morrison, S.J., 1979. Biochemical measurements of microbial mass and activity from envir-onmental samples. In: Costerton, J.W., Colwell, R.R. (Eds.). Native Aquatic Bacteria: Enumeration, Activity, and Ecology, ASTM STP 695. American Society for Testing and Materials, Philadelphia, PA, pp. 69±81.
The rhizosphere and spermosphere Principles and Appli-cations of Soil Microbiology Factor Analysis: Statistical Methods and Practical Issues
- A C Kennedy
- D M Sylvia
- J J Fuhrmann
- P G Hartel
- D A Zuberer
Kennedy, A.C., 1998. The rhizosphere and spermosphere. In: Sylvia, D.M., Fuhrmann, J.J., Hartel, P.G., Zuberer, D.A. (Eds.). Principles and Appli-cations of Soil Microbiology. Prentice Hall, Upper Saddle River, New Jersey, pp. 389±407. Kim, J.-O., Mueller, C.W., 1978. Factor Analysis: Statistical Methods and Practical Issues. Sage Publications, Beverly Hills, CA.
The rhizosphere and spermosphere Principles and Applications of Soil Microbiology
- A C Kennedy
Kennedy, A.C., 1998. The rhizosphere and spermosphere. In: Sylvia, D.M.,
Fuhrmann, J.J., Hartel, P.G., Zuberer, D.A. (Eds.). Principles and Applications of Soil Microbiology. Prentice Hall, Upper Saddle River, New
Jersey, pp. 389±407.
Principles and Applications of Soil Microbiology
- A C Kennedy
- D M Sylvia
- J J Fuhrmann
- P G Hartel
Kennedy, A.C., 1998. The rhizosphere and spermosphere. In: Sylvia, D.M.,
Fuhrmann, J.J., Hartel, P.G., Zuberer, D.A. (Eds.). Principles and Applications of Soil Microbiology. Prentice Hall, Upper Saddle River, New
Jersey, pp. 389±407.
Phospholipid, ester-linked fatty acid profiles as reproducible assays for changes in prokaryotic community structure of estuarine sediments
- Guckert
The rhizosphere and spermosphere
- Kennedy