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SEM photomicrograph of microbial colonization on the surface of biochar at 90 days of incubation. A scale: a) Bar ¼ 10 mm, b) Bar ¼ 5 mm, c) Bar ¼ 10 mm, d) Bar ¼ 10 mm, e) Bar ¼ 10 mm, f) Bar ¼ 5 mm, g) Bar ¼ 10 mm, h) Bar ¼ 5 mm. Biochar350 in low pH low soil without (a) and with (b) ryegrass. Biochar700 in low pH low soil, without (c) and with (d) ryegrass. Biochar350 in high pH high soil, without (e) and with (f) ryegrass. Biochar700 in pH high soil, without (g) and with (h) ryegrass.
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Biochar has been widely proposed as a soil amendment, with reports of benefits to soil physical, chemical and biological properties. To quantify the changes in soil microbial biomass and to understand the mechanisms involved, two biochars were prepared at 350 °C (BC350) and 700 °C (BC700) from Miscanthus giganteus, a C4 plant, naturally enriched wi...
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... Electron Microscopy (SEM) showed that the Mis- canthus cell structure was largely intact after pyrolysis, albeit apparently consisting of partially carbonised structural material. Microbial colonization after 90 days on the surfaces of BC350 and BC700 is shown in Fig. 3. Biochar350 was heavily colonized with bacteria and fungi in all treatments. These results were consistent with the measured increases in biomass C and ATP with biochar350 addition (Fig. 1). No microbial colonization of BC700 was observed in the high pH soil (Fig. 3) but, in the low pH soil, numerous fungal hyphae were detected on the ...
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... colonization after 90 days on the surfaces of BC350 and BC700 is shown in Fig. 3. Biochar350 was heavily colonized with bacteria and fungi in all treatments. These results were consistent with the measured increases in biomass C and ATP with biochar350 addition (Fig. 1). No microbial colonization of BC700 was observed in the high pH soil (Fig. 3) but, in the low pH soil, numerous fungal hyphae were detected on the surface of BC700. After 180 days of incubation, no bacterial cells were observed (SEM electron micro- graphs not shown) in this treatment. More colonization images by SEM are given in supplementary ...
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... results are consistent with the SEM data which showed no colonization of BC700 in the high pH soil (Figs. 1 and 3). Ryegrass addition increased the biochar derived biomass C in all biochar amended soils, except in the low pH soil amended with BC700 (Fig. 4). ...
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... increase in microbial colonization was observed in the high pH soil with BC700 addition, compared to BC350 (Figs. 1 and 3). This might be because the availability of C, N and other nutrients were low in BC700, as most were lost during pyrolysis (Table 1). ...
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... toxic to biomass C resulting in less biomass C and ATP (Fig. 1). However, in the low pH soil, microbial biomass C was little affected (7% less at day 90 but 8% more at day 180, and ATP even increased by 22% and 38% at day 90 and 180, respectively). This was also consistent with the parallel microbial colonization observed by SEM at day 90 ( Fig. 3) and the biochar derived biomass C synthesised (Fig. 4). It is not clear why BC700 caused such a drastic decrease in biomass in the high pH soil, while the biomass increased in the low pH soil (Fig. 1). Microorganisms are very sensitive to changes in soil pH, which can change the microbial biomass, activity and community structure ...
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... Warnock et al. (2010) observed decreased of Arbuscular Mycorrhizal (AM) fungi following biochar addition to a soil with an initial pH of 7.9, and suggested that there might be mechanisms involved other than direct pH effects. In our study, the pH increase caused by addition of BC700 could only explain the biomass C increase in the low pH soil (Figs. 1, 3 and 4). This also confirms our hypothesis that the pH increase caused by BC700 mainly stimulates microbial production in low pH but not high pH soils. ...
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... are affected by the changes in the soil microenvironment following biochar addition, clearly, bio- char mineralization is also largely controlled by the microbial biomass. Furthermore, in a biochar amended soil, the fresh organic matter inputs (e.g. plant residues or root exudates) are likely to interact with microorganisms in the charsphere (Figs. 3 and 7). Biomass C and ATP increased with ryegrass addition (Fig. 1) and the biochar derived biomass C concentration was increased with ryegrass (Fig. 4). This means that, in addition to the C and nutrients provided by biochar alone, the extra C and energy available to the biomass from the ryegrass enabled more efficient synthesis of bio- char ...
Citations
... But Xu et al. [66] found that woodbased biochar did not alter microbial functional diversity represented by the Shannon diversity index. Usually, biochar treatment increased the CFU in a similar way to our study [67] however, some studies detected a decrease or no significant difference compared to the control [68,69]. ...
The soil degradation processes may cause long-term serious problems in various areas of life on Earth, thus mitigation of these processes by environmental-friendly, innovative soil protection methods is necessary. Biochar produced from organic wastes or by-products by pyrolysis may have several positive properties as additive in soil improvement technologies. In our complex research applying a tiered approach we assessed the main properties of a beech-wood biochar produced from a high volume by-product of a food industry technology. Then we studied in 4-months microcosm experiments the applicability of this biochar as amendment mixed into an acidic, degraded sandy soil. In addition, to forecast the long-term effects of the biochar, artificial physical and biological aging experiments were conducted.Based on the results, the beech-wood biochar was able to shift the acidic pH of the soil to the alkaline range and the electric conductivity of the soil increased with incremental biochar doses. Biochar addition significantly increased the microbial activity, as well. The results had clearly shown that during the mid-term experiment not even the highest biochar dose (15%) had inhibitive effect, but it rather improved several soil parameters. Furthermore, the biochar had positive effect on the soil water holding capacity, and the available soil nutrient and organic matter content. The results of the aging experiments generally showed also favourable effects and demonstrated that the aging-mediated changes differed according to the soil types. Therefore, we have concluded that biochar application requires a char by char and soil by soil testing prior to field application.
... The functional groups on the surface of the rice biochar were the adsorption sites of organic matter, and these oxygen-containing functional groups underwent proton absorption/dissociation. After adsorption, the superimposed peaks of the C C skeleton vibration of the benzene ring and NH 2 variable angle vibration occurred at 1601 cm −1 for rice stalk biochar (Luo et al., 2013). The presence of O H stretching vibration between 3500 and 2000 cm −1 was due to the remarkably strong hydrogen bonding force of the carboxylic acid carboxyl group forming dimer, which causes the O H stretching vibration to become a diffuse broad-spectrum band (Tayibi et al., 2019). ...
Rice crab coculture is a new ecological agriculture model combining rice cultivation and crab farming. Current research related to rice crab coculture only focuses on production theory and technical system establishment, while ignoring the potential ecological risk of Polycyclic aromatic hydrocarbon(PAHs) in rice crab coculture sediment. In this study, rice straw was used to make rice straw biochar to explore the performance and mechanism of inhibiting release of phenanthrene(PHE) from rice-crab coculture sediments to overlying water with rice stalk biochar. The kinetic and isotherm adsorption data were best represented by the Langmuir model and pseudo-second-order model with a maximum adsorption capacity of 53.35 mg/g at 12 h contact time. The results showed that PHE was released from the rice-crab substrate to the overlying water in dissolved and particle forms as a result of bioturbation, and the PHE concentrations in dissolved and particle forms were 20.9 μg/L and 14.22 μg/L, respectively. This leads to secondary ecological risks in rice-crab co-culture systems. This is related to dissolved organic carbon(DOC) carrying the dissolved PHE and total suspended solids(TSS) carrying the particle PHE in the overlying water. Due to its large specific surface area, rice straw biochar is rich in functional groups, providing multiple hydrophobic adsorption sites. After adding rice straw biochar at 0.5 % w/w (dry weight) dose, the removal efficiency of dissolved and particulate PHE in the overlying water were 78.99 % and 42.11 %, respectively. Rice straw biochar is more competitively adsorbed PHE in the overlying water than TSS and DOC. The removal efficiency of PHE from the sediment was 52.75 %. This study confirmed that rice stalk biochar could effectively inhibit PHE migration and release in paddy sediment. It provides an environment-friendly in situ remediation method for the management of PAHs pollution from crab crops in rice fields.
... These results together explained the positive effects of biochar on the availability of soil resources, such as TN and AK, which showed the same trend in the present study. Biochar can increase soil microbial diversity and metabolic activities [12,28], thus resulting in positive effects on the diversity of both microbial taxa and functional genes. In addition, increases in the soil available resources might diversify the bacteria or archaea communities hosting and diversifying the virus communities [29,30]. ...
Despite the well-documented role of biochar in promoting soil quality and crop productivity , the underlying biological mechanisms remain poorly understood. Here, we explored the effects of straw biochar on soil microbiome in the rhizosphere from wheat using metagenomic sequencing. Our results showed that straw return decreased the yields of wheat, while the straw biochar return increased the wheat yields. Further, both the richness and community composition confirmed different effects of the straw return and straw biochar return. The straw biochar return also resulted in greater rhizosphere effects from wheat, represented by resource availability, including soil organic carbon, soil total nitrogen, available phosphorus, and available potassium. The rhizosphere effects from wheat, represented by microbial metabolism genes involved in carbon, nitrogen, phosphorus, and potassium cycling, however, were decreased by straw biochar returning. In addition, the rhizosphere effects from nitrogen content and the nitrogen cycling genes showed negative relationships with wheat yields. Together, these results revealed that straw biochar enhanced soil resource availability but suppressed microbial metabolism genes in the rhizosphere from wheat, supporting the idea that straw biochar serves as a nutrient pool for crops.
... Such results were expected as biochar is known to have a liming effect in acidic soils by increasing the soil pH. Adding biochar to soil must have a much stronger effect on soil microbial biomass in acidic soils but may lead to little variation in alkaline soils (Luo et al., 2013). In addition, the effects of biochar were more pronounced in soils with a low SOC content as the SOC content was negatively correlated to the PC of soil microbial biomass. ...
Changes in soil microbial communities may impact soil fertility and stability because microbial communities are key to soil functioning by supporting soil ecological quality and agricultural production. The effects of soil amendment with biochar on soil microbial communities are widely documented but studies highlighted a high degree of variability in their responses following biochar application. The multiple conditions under which they were conducted (experimental designs, application rates, soil types, biochar properties) make it difficult to identify general trends. This supports the need to better determine the conditions of biochar production and application that promote soil microbial communities. In this context, we performed the first ever meta-analysis of the biochar effects on soil microbial biomass and diversity (prokaryotes and fungi) based on high-throughput sequencing data. The majority of the 181 selected publications were conducted in China and evaluated the short-term impact (<3 months) of biochar. We demonstrated that a large panel of variables corresponding to biochar properties, soil characteristics, farming practices or experimental conditions, can affect the effects of biochar on soil microbial characteristics. Using a variance partitioning approach, we showed that responses of soil microbial biomass and prokaryotic diversity were highly dependent on biochar properties. They were influenced by pyrolysis temperature, biochar pH, application rate and feedstock type, as wood-derived biochars have particular physico-chemical properties (high C:N ratio, low nutrient content, large pores size) compared to non-wood-derived biochars. Fungal community data was more heterogenous and scarcer than prokaryote data (30 publications). Fungal diversity indices were rather dependent on soil properties: they were higher in medium-textured soils, with low pH but high soil organic carbon. Altogether, this meta-analysis illustrates the need for long-term field studies in European agricultural context for documenting responses of soil microbial communities to biochar application under diverse conditions combining biochar types, soil properties and conditions of use.
... In contrast, several studies did not support biochar's impact on soil productivity and nutritional crop composition. Investigators reported controversy in their findings, with biochar having positive, negative, or insignificant effects on soil microbial communities depending on the biochar source and soil types [54][55][56]. Table 1 listed the activity of urease, invertase, acid, and alkaline phosphatase in each of the animal manures used in growing turnips, arugula, and mustard plants. Soil enzymes as bioindicators of soil health had been investigated [57,58]. ...
The need for soil fumigants of natural origin such as glucosinolates (GSLs) has increased due to the general prevention of manmade soil fumigants. GSLs and other phytochemicals (vitamin C and phenols) present in Brassica vegetables such as turnips, arugula, and mustard have antioxidant properties, and hence have important health attributes. The study examined how different soil amendments (chicken manure CM, vermicompost Vermi, horse manure HM, sewage sludge SS, elemental inorganic fertilizer Inorg, organic fertilizer Org, and biochar) impact the concentrations of glucosinolates (GSLs), vitamin C, phenols, and reducing sugars in three varieties of turnips (Purple Top White Globe PTWG, Scarlet Queen Red SQR, and Tokyo Cross TC), arugula, and mustard greens grown under field conditions. The results showed that mustard greens contained higher concentrations of GSLs (974 µg g−1 fresh shoots) than arugula (651 µg g−1 fresh shoots), and the TC variety of turnip had the highest concentrations of GSLs, vitamin C, and sugars. Additionally, amending the soil with SS, CM, and HM significantly increased the vitamin C content in mustard shoots by 82%, 90%, and 31%, respectively, and the total phenols by 77%, 70%, and 36%, respectively, compared to the control treatment. The increased inorganic fertilizers cost, and availability of large amounts of animal manure made animal manure application to cropland an attractive disposal option.
... Conversely, Ameloot et al. (2013) reported a 29% increase in MBC in sandy loam soils on application of biochar produced from willow wood at 700°C. Similarly, Luo et al. (2013) reported greater MBC in clay loam soils amended with biochar produced at 700°C. There is a need of applying organic amendments in conjugation with biochar to offset the short-term reduction effect on MBC. ...
Intensive cultivation of agricultural soils causes soil degradation which emphasizes
the need for sustainable soil management. Biochar, a pyrolysed carbon rich
material has gained great interests among the researchers because of its ecofriendly
benefits in addition to soil quality enhancement. Reviews on biochar,
mainly confined to its environmental benefits like carbon sequestration and
climate change. In this review, we summarize i) the effect of biochar
application on soil properties (physical, chemical, biological), ii) remediation
potential of biochar in heavy metal contaminated soils and iii) its impact on
crop productivity. The properties of biochar like pH, greater surface area,
cation exchange capacity, and nutrient content positively influences the soil
properties and ultimately improves the soil fertility. Their effectiveness depends
on biochar type, its dosage, soil type, etc. General trends from this review indicated
that biochar as an effective amendment in acid soils than the alkaline or calcareous
soils. Furthermore, the biochar effects are studied mostly under controlled
conditions in laboratory, which needs to be validated under field conditions
having varied soil types and agro-climatic zones.
KEYWORDS
biochar, soil fertility, crop productivity, heavy metal remediation, pyrolysed carbon
... Conversely, Ameloot et al. (2013) reported a 29% increase in MBC in sandy loam soils on application of biochar produced from willow wood at 700°C. Similarly, Luo et al. (2013) reported greater MBC in clay loam soils amended with biochar produced at 700°C. There is a need of applying organic amendments in conjugation with biochar to offset the short-term reduction effect on MBC. ...
Intensive cultivation of agricultural soils causes soil degradation which emphasizes the need for sustainable soil management. Biochar, a pyrolysed carbon rich material has gained great interests among the researchers because of its eco-friendly benefits in addition to soil quality enhancement. Reviews on biochar, mainly confined to its environmental benefits like carbon sequestration and climate change. In this review, we summarize i) the effect of biochar application on soil properties (physical, chemical, biological), ii) remediation potential of biochar in heavy metal contaminated soils and iii) its impact on crop productivity. The properties of biochar like pH, greater surface area, cation exchange capacity, and nutrient content positively influences the soil properties and ultimately improves the soil fertility. Their effectiveness depends on biochar type, its dosage, soil type, etc. General trends from this review indicated that biochar as an effective amendment in acid soils than the alkaline or calcareous soils. Furthermore, the biochar effects are studied mostly under controlled conditions in laboratory, which needs to be validated under field conditions having varied soil types and agro-climatic zones.
... With our pH adjustment, the effect of ash content should be negligible compared to the effects of PyOM-C. The porous nature of PyOM can adsorb water, organic materials and nutrients, and provide a habitat for microbes (23,72). Furthermore, PyOM sorption of acyl-homoserine lactone (AHL) intercellular signaling molecules can disrupt cell-cell communication among bacteria and affect C mineralization, especially in the short-term following addition of fresh PyOM (21). ...
Wildfires can either negatively impact soil carbon (C) stocks through combustion or increase soil carbon stocks through the production of pyrogenic organic matter (PyOM), which is highly persistent and can affect non-pyrogenic soil organic carbon (SOC) mineralization rates. In this study, we used fine-resolution 13CO2 flux tracing to investigate PyOM-C mineralization, soil priming effects, and their impacts on soil microbial communities in a Californian mixed conifer forest Xerumbrept soil burned in the 2014 King Fire. We added PyOM produced from pine biomass at 350 °C and 550 °C to the soil and separately traced the mineralization of 13C-labeled water-extractable and non-water-extractable PyOM-C fractions in a short-term incubation.
Our results indicate that the water-extractable fraction is 10-50x more mineralizable in both 350 °C and 550 °C PyOM treatments than the SOC or non-water-extractable PyOM fraction. 350 °C PyOM addition led to a short-term positive priming effect, likely due to co-metabolism of easily mineralizable PyOM-C and the SOC, whereas 550 °C PyOM addition induced negative priming, potentially due to physical protection of SOC. We observed significant shifts in bacterial community composition in response to both 350 °C and 550 °C PyOM, with positive PyOM responders belonging to the genera Noviherbaspirillum, Pseudonocardia, and Gemmatimonas. In contrast, fungal communities were less responsive to PyOM additions. Our findings expand our understanding of the post-fire cycling of PyOM and SOC, providing insights into the microbial mineralization of different PyOM-C fractions and their influence on soil C dynamics in fire-affected ecosystems.
... Vol:. (1234567890) litter biomass (Luo et al., 2013) reduce carbon emissions from soils. The amount of organic matter in an ecosystem influences soil respiration in an ecosystem by altering the water retention capacity, pore space, and microbial activity in the soil (Moyano et al., 2013). ...
Forests serve as a sink and source of carbon and play a substantial role in regional and global carbon cycling. The Himalayan forests act as climate regulators of the Hindukush region, which is experiencing climate change at a high pace, and a proper understanding of these systems is necessary to mitigate this problem. We hypothesize that the variance of abiotic factors and vegetation will influence the carbon sink and source function of the different forest types of the Himalayas. Carbon sequestration was computed from the increment of carbon stocks estimated allometrically using Forest Survey of India equations, and soil CO2 flux was determined by the alkali absorption method. The carbon sequestration rate and CO2 flux by the different forests exhibited a negative relation. The carbon sequestration rate was highest with minimum emission in the temperate forest, while the tropical forest recorded the least sequestration and maximum carbon flux rate. The Pearson correlation test between carbon sequestration and tree species richness and diversity revealed a positive-significant influence but negative relation with climatic factors. An analysis of variance indicated significant seasonal differences between the rate of soil carbon emissions due to variations in the forest. A multivariate regression analysis of the monthly soil CO2 emission rate shows high variability (85%) due to fluctuations of climatic variables in the Eastern Himalayan forests. Results of the present study revealed that the carbon sink and source function of forests respond to changes in forest types, climatic variables, and edaphic factors. Tree species and soil nutrient content influenced carbon sequestration, while shifts in climatic factors influenced soil CO2 emission rate. Increased temperature and rainfall may further change the soil quality by enhancing soil CO2 emission and reducing soil organic carbon, thereby impacting this region’s carbon sink and source function. Enhancing tree diversity in the forests of this region may be beneficial for retarding this impact.
... In this survey, soil pH was increased significantly from ~5.5 in forests to ~6.7 in vineyard topsoils. This could be the reason for higher protist diversity in vineyard soils (Fig. 1B) since neutral pH is the optimal condition for microbial growth (Luo et al., 2013;Malik et al., 2018;Silva-Sánchez et al., 2019). Moreover, soil nutrients, such as TN, TP, and CEC increased significantly in agricultural soils in this study (Table 2). ...
