Article

Soil CO2 emissions from a cultivated Mollisol: Effects of organic amendments, soil temperature, and moisture

March 2013
European Journal of Soil Biology 55:83-90

DOI:10.1016/j.ejsobi.2012.12.009

Project: GHGs emission from Mollisols as affected by agricultural management practices

Authors:

Lu-Jun Li

Chinese Academy of Sciences

Memo You

Changchun University of Science and Technology

Xueli Ding

Nanjing University of Information Science & Technology

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A field experiment was conducted to examine the influences of long-term applications of maize straw and organic manure on carbon dioxide (CO2) emissions from a cultivated Mollisol in northeast China and to evaluate the responses of soil CO2 fluxes to temperature and moisture. Soil CO2 flux was measured using closed chamber and gas chromatograph techniques. Our results indicated that the application of organic amendments combined with fertilizer nitrogen, phosphorus and potassium (NPK) accelerated soil CO2 emissions during the maize growing season, whereas NPK fertilization alone did not impact cumulative CO2 emissions. Cumulative CO2 emissions were higher from soils amended with pig manure relative to those with maize residue. Cumulative CO2 emissions during the growing season were 988 and 1130 g CO2 m(-2) under applications of 7500 and 22,500 kg ha(-1) pig manure combined with NPK, respectively, which were 42 and 63% higher than the emissions from the control (694 g CO2 m(-2)). The applications of 2250 and 4500 kg ha(-1) maize straw combined with NPK marginally increased soil CO2 emissions by 23 and 28% compared with the control, respectively. A log-transformed multiple regression model including both soil temperature and moisture explained 50-88% of the seasonal variation in soil CO2 fluxes. Cumulative soil CO2 emissions were affected more by applied treatments than by soil temperature and moisture. Our results suggest that the magnitude of the impact of soil amendments on CO2 emissions from Mollisols primarily depends on the type of organic amendments applied, whereas the application rate has limited impacts. (C) 2013 Elsevier Masson SAS. All rights reserved.

Microbial-Mediated Emissions of Greenhouse Gas from Farmland Soils: A Review

Article

Full-text available

Nov 2022

The greenhouse effect is one of the concerning environmental problems. Farmland soil is an important source of greenhouse gases (GHG), which is characterized by the wide range of ways to produce GHG, multiple influencing factors and complex regulatory measures. Therefore, reducing GHG emissions from farmland soil is a hot topic for relevant researchers. This review systematically expounds on the main pathways of soil CO2, CH4 and N2O; analyzes the effects of soil temperature, moisture, organic matter and pH on various GHG emissions from soil; and focuses on the microbial mechanisms of soil GHG emissions under soil remediation modes, such as biochar addition, organic fertilizer addition, straw return and microalgal biofertilizer application. Finally, the problems and environmental benefits of various soil remediation modes are discussed. This paper points out the important role of microalgae biofertilizer in the GHG emissions reduction in farmland soil, which provides theoretical support for realizing the goal of “carbon peaking and carbon neutrality” in agriculture.

Improving Carbon Dioxide Concentration, Growth and Yield of Tomato Using Fresh Manure and Agronet Cover

Article

Full-text available

May 2022

Arable land area is declining in many tropical and sub-tropical regions and increasing tomato (Solanum lycopersicum L.) production is necessary due to its high demand. Food security amid scarcity of arable land could be achieved through intensification as a way of maximizing productivity per unit area of available arable land. Trials were conducted at the Horticulture Research and Teaching Field, Egerton University, Njoro, Kenya, to evaluate effects of agronet cover and fresh manure on carbon dioxide (CO2) concentration in the air around the crop canopy and tomato plant development. In addition to CO2 concentration levels, stem diameter, plant height, number of internodes and branches, number of fruit and fresh fruit weight were determined. Use of agronet cover and fresh manure resulted in higher CO2 concentration and enhanced tomato growth and yield. The highest CO2 concentration in the air around the crop canopy was in plots treated with fresh goat dung and those covered with agronet; the lowest CO2 concentration was in plots with no manure and those without agronet at all data collection dates. Application of fresh cow dung and covering plots with agronet stimulated tomato stem elongation; application of fresh goat dung and covering with agronet enhanced stem diameter, number of internodes and branches. Higher tomato yields were obtained with use of fresh manure and agronet cover. There were differences in response of tomato plants to fresh manure source with fresh goat dung showing greater potential for use in CO2 enrichment and enhancing tomato crop performance. Use of fresh manure and agronet covers could enrich CO2 levels in open field tomato production leading to improved growth and yield.

Straw and residual film management enhances crop yield and weakens CO2 emissions in wheat–maize intercropping system

Article

Full-text available

Jul 2021

Higher CO2 emissions and lower crop productivity are becoming thorny problems and restricted sustainable development of agriculture in arid inland areas. Intercropping has been shown to enhance crop productivity. However, Intercropping generally requires more input that led to an increase in CO2 emissions. It is unknown whether designing tillage and film mulching in reduction could decrease soil CO2 emissions in intercropping. Therefore, we integrated no tillage combined with residual film mulching and straw returning into wheat–maize intercropping. The maximal soil CO2 fluxes (Fs) with intercropping was decreased by 12–21% compared to sole maize. Residual film mulching combined with straw returning (NTSMI) significantly reduced average Fs during the entire period of crop growth by 14–15%, compared with the conventional tillage (CTI). Soil CO2 emissions (CE) with intercropping was 18–20% less than that with sole maize and the NTSMI reduced CE by 12–16% compared to the CTI. The NTSMI boosted total grain yields (GY) by 14–17%, compared with the CTI. Wheat–maize intercropping significantly enhanced soil CO2 emission efficiency (CEE) by 33–41% in comparison to sole maize, and CEE with NTSMI was increased by 29–40% than that of CTI. A quadratic function for aboveground biomass (BA) combined with two linear functions for soil temperature (Ts) and soil water-filled pore space (WFPS) was suitable for the monitored results. A multiple regression model composed of the above three factors can explain 73–91% of the Fs variation. Crop biomass accumulation at the time of maximal Fs was less with intercropping compared with sole maize. The structural equation indicated that the BA synergistic effect on CEE through combining negative effects on CE and positive effects on GY in intercropping. In conclusion, no tillage with straw returning and residual film mulching in wheat–maize intercropping was confirmed to be an optimum management practice to reducing soil CO2 emissions and enhancing soil CO2 emission efficiency in arid inland agroecosystem.

EFFECT OF APPLICATION OF SHEEP MANURE AND ITS BIOCHAR ON CARBON EMISSIONS IN SALT AFFECTED CALCAREOUS SOIL IN SANLIURFA REGION SE TURKEY

Article

Full-text available

Mar 2019
FRESEN ENVIRON BULL

The terrestrial carbon (C) cycle is a very important part of the global C cycle. Researches have been carried out aimed at reduction of the increasing C emissions and soil salinity that result from intense human activity, in recent years. Organic matter that has been transformed into biochar is more resistant to decomposition and disintegration activity of microorganisms. Therefore, source of organic matter is becoming important in terms of reduction of C emission. The effects of application of sheep manure (SM) and sheep manure biochar (SMBC) on the C dynamics of the calcareous soils with different soil salinity level has been examined in this study. For this aim, soil samples were taken from the Harran Plain and measured by applying different salt concentrations (EC=0, 4, 8, 12 and 16 dS m-1) in laboratory conditions. At the end of the study, amount of CO2-C flux from the soils was compared with the control group, a reduction was observed in both treatments (SM and SMBC), the greatest reduction being observed in SMBC. While reductions of 15.62% (EC=4 dS m-1), 19.5% (EC=8 dS m-1), 40.15% (EC=12 dS m-1) and 48.43% (EC=16 dS m-1) were observed in samples with SM, the corresponding reductions in samples with SMBC were observed as 21.76%, 52.94%, 58.82% and 67.64% respectively at the end of the first month of the study. As a result, CO2 efflux was decreased in line with increasing EC values. However, this situation is considered not to be dependent only on the increase in amount of saline in the soil, but at the same time to be related to the biochar added to the soil. When comparing the effect of SM and SMBC treatments to carbon - storage of soil, SMBC resulted in lower carbon emissions. Since SM undergoes a normal process and is mineralized, more CO2 is released. Therefore, in cases where organic waste is added to soil, converting this to biochar first will be of great importance both for the soil and for atmospheric CO2.

Effects of Long-Term Organic–Inorganic Nitrogen Application on Maize Yield and Nitrogen-Containing Gas Emission

Article

Full-text available

Mar 2023

A sustainable model of combined organic–inorganic fertilizer application for high maize yields and environmental health is important for food security. The short-term combined application of organic and inorganic fertilizers can improve crop yields; however, the effect of different proportions of organic and inorganic fertilizers on the maize yield and nitrogen gas emissions in a long time series has not been reported. In this study, field experiments and DeNitrification-DeComposition (DNDC) model simulations were used to study the long-term effects of substituting inorganic fertilizers with organic fertilizers on crop yields and nitrogen-containing gas emissions. Six treatments were included: no nitrogen (CK); urea (U1); and 25%, 50%, 75%, and 100% of the urea N substituted by organic fertilizers (U3O1, U1O1, U1O3, and O1, respectively). The DNDC model was calibrated using the field data from the U1 treatment from 2018 to 2020 and was validated for the other treatments. The results showed that this model could effectively simulate crop yields (e.g., nRMSE < 5%), soil NH3 volatilization, and N2O emissions (nRMSE < 25%). In addition, long-term (26 years) simulation studies found that the U1O1 treatment could considerably increase maize yields and ensure yield stability, which was 15.69–55.31% higher than that of the U1 treatment. The N2O, NH3, and NO emissions were in the descending order of U1 > U3O1 > O1 > U1O3 > U1O1, and the total nitrogen-containing gas emissions from the U1O1 treatment decreased by 53.72% compared with the U1 treatment (26 years). Overall, substituting 50% of inorganic nitrogen with organic nitrogen could maintain the high yield of maize and reduce emissions of nitrogen-containing gases, constituting a good mode for the combined application of organic–inorganic nitrogen in this area.

Volatile Organic Compound (VOC) Profiles of Different Trichoderma Species and Their Potential Application

Article

Full-text available

Sep 2022
J. Fungi

Fungi emit a broad spectrum of volatile organic compounds (VOCs), sometimes producing species-specific volatile profiles. Volatilomes have received over the last decade increasing attention in ecological, environmental and agricultural studies due to their potential to be used in the biocontrol of plant pathogens and pests and as plant growth-promoting factors. In the present study, we characterised and compared the volatilomes from four different Trichoderma species: T. asperellum B6; T. atroviride P1; T. afroharzianum T22; and T. longibrachiatum MK1. VOCs were collected from each strain grown both on PDA and in soil and analysed using proton transfer reaction quad-rupole interface time-of-flight mass spectrometry (PTR-Qi-TOF-MS). Analysis of the detected vola-tiles highlighted a clear separation of the volatilomes of all the four species grown on PDA whereas the volatilomes of the soil-grown fungi could be only partially separated. Moreover, a limited number of species-specific peaks were found and putatively identified. In particular, each of the four Trichoderma species over-emitted somevolatiles involved in resistance induction, promotion of plant seed germination and seedling development and antimicrobial activity, as 2-pentyl-furan, 6PP, ace-tophenone and p-cymene by T. asperellum B6, T. atroviride P1, T. afroharzianum T22 and T. longibrachi-atum MK1, respectively. Their potential role in interspecific interactions from the perspective of biological control is briefly discussed.

Soil Temperature Prediction with Long Short Term Memory (LSTM)

Article

Full-text available

Jul 2022

Soil temperature not only affects many soil properties, but also has a significant effect on plant development. Knowing and correct estimation of soil temperature is important for both soil management and crop production. The accuracy of temperature forecasts is very important, especially for the countries that stand out with their agriculture-based economies. Therefore, in recent years, different artificial intelligence methods have been used in soil temperature predictions. Deep learning methods lead the way in achieving high prediction accuracy. In this study, a Long Short-Term Memory (LSTM) network, which is a deep learning (DL) sub-architecture, is proposed to create an effective model for soil temperature prediction. The data used in the study are the daily soil temperatures at a depth of 50 cm for the years 2013-2021 of Bingöl province. For the training of the proposed LSTM model, 89% of the data set within the scope of the study was used, and. The remaining 11% was estimated by the model for assessing model success. The RMSE value as a result of the estimation made by the trained LSTM model was obtained as 1.25. The high estimation accuracy of the proposed model showed that this model could be successfully applied in temperature data estimation studies.

Soil CO2 emissions in cropland with fodder maize (Zea mays L.) with and without riparian buffer strips of differing vegetation

Article

Full-text available

Jul 2022
AGROFOREST SYST

Vegetated land areas play a signifcant role in determining the fate of carbon (C) in the global C cycle. Riparian bufer vegetation is primarily implemented for water quality purposes as they attenuate pollutants from immediately adjacent croplands before reaching freashwater systems. However, their prevailing conditions may sometimes promote the production and subsequent emissions of soil carbon dioxide (CO2). Despite this, the understanding of soil CO2 emissions from riparian bufer vegetation and a direct comparison with adjacent croplands they serve remain elusive. In order to quantify the extent of CO2 emissions in such an agro system, we measured CO2 emissions simultaneously with soil and environmental variables for six months in a replicated plot-scalefacility comprising of maize cropping served by three vegetated riparian bufers, namely: (i) a novel grass riparian bufer; (ii) a willow riparian bufer, and; (iii) a woodland riparian bufer. These bufered treatments were compared with a no-bufer control. The woodland (322.9±3.1 kg ha−1 ) and grass (285±2.7 kg ha−1 ) riparian bufer treatments (not signifcant to each other) generated signifcantly (p=<0.0001) the largest CO2 compared to the remainder of the treatments. Our results suggest that during maize production in general, the woodland and grass riparian bufers serving a maize crop pose a CO2 threat. The results of the current study point to the need to consider the benefts for gaseous emissions of mitigation measures conventionally implemented for improving the sustainability of water resources.

Temperature sensitivity of organic matter mineralization as affected by soil edaphic properties and substrate quality

Article

Full-text available

Mar 2022
CATENA

Warming in ecosystems simultaneously changes soil temperatures and inputs of organic matter into soils. Soil chemical properties and exogenous substrate inputs both have significant effects on the temperature sensitivity (Q10) of mineralization. In this study, three soil types (Cambisol, Chernozem and Luvisol) were collected from natural forests at three latitudes in temperate China, whereas the vegetation types are mixed broadleaf-conifer, broadleaf and conifer respectively. The soils differed in soil organic carbon (SOC) contents in the order Chernozem (8.5%), Luvisol (6%), Cambisol (3.6%). The soils were incubated for 40 days at three temperatures (5, 15, and 25 °C). Glucose and maize leaf powder were added as exogenous substrates. To add the same amounts of soluble carbon glucose and maize leaf powder were added at the rate of 2 and 4 mg C g⁻¹ soil, respectively. Independent of substrate addition, the Chernozem had the highest cumulative CO2 efflux under all temperature treatments. Maize addition accelerated cumulative CO2 efflux more than glucose in most treatments. The Q10 value was higher (P < 0.05) in the Chernozem (1.29 ∼ 1.49) than the Cambisol (1.17 ∼ 1.28) and the Luvisol (1.10 ∼ 1.29), both in the treatments and the control. Soil Q10 was positively correlated (P < 0.001) with DOC and mineral N content, but negatively correlated (P < 0.001) with the MBC/MBN ratio. However, the effect of exogenous substrate addition on Q10 varied between the different soil types. Addition of both substrates reduced Q10 by 8.7 ∼ 13.4% in the Chernozem and by 10 ∼ 14.0% in the Luvisol, whereas maize input increased (P < 0.05) Q10 by 7.6% in the Cambisol. These results suggested that DOC, mineral N and MBC/MBN ratio significantly influenced Q10, whereas the effects of exogenous substrates on soil respiration and Q10 were highly dependent on SOC content and substrate type.

Soybean yield and quality relative to Mollisols fertility with 7‐yr consecutive manure application under maize‐soybean rotation

Article

Aug 2021

Improving soil productivity is the only solution to increase grain production by 1% annually for feeding the rising population within the next 20 years in China. A 7-yr consecutive manure addition experiment was conducted under a soybean [Glycine max (Merrill.) L.] and maize (Zea mays L.) rotation in Mollisols. Treatments were as follows: CK: the non-fertilizer control; CF: chemical fertilizer (NPK); CFM1: CF+15 Mg/ha cattle manure; CFM2: CF+30 Mg/ha cattle manure. The results showed CFM1 significantly increased soybean yield by 22-105% and 21-86% compared to CK, and CF during 2014-2018. The consecutive manure addition significantly increased the proportion of macro-aggregates (1-0.25 mm) but decreased the proportion of micro-aggregates (0.25-0.053 mm) and slit (< 0.053 mm). The SOC storage in the large (> 1 mm) and small macro-aggregates (1-0.25 mm) was higher (by 24-156%) under manure addition than that under CK and CF. The soil productivity was enhanced by manure addition because of the increase in soil available nutrients, i.e., NH 4 + and NO 3 − , and Olsen-P, all of which had positive correlations with the yield increase. At least 36% of soybean yield variation under CFM1 could be attributed to the indirect effect of pH value on increasing soil available nutrients concentrations. The manure addition increased soybean seed oil concentration but decreased protein concentration. However, there were no differences in yield and quality between CFM1 and CFM2 after 7-yr of the treatment. It suggests that manure addition at 15 Mg/ha is a practical approach to improve Mollisols’ productivity and SOC stability. This article is protected by copyright. All rights reserved.

The Cold Region Critical Zone in Transition: Responses to Climate Warming and Land Use Change

Article

Full-text available

Oct 2021

Global climate warming disproportionately affects high-latitude and mountainous terrestrial ecosystems. Warming is accompanied by permafrost thaw, shorter winters, earlier snowmelt, more intense soil freeze-thaw cycles, drier summers, and longer fire seasons. These environmental changes in turn impact surface water and groundwater flow regimes, water quality, greenhouse gas emissions, soil stability, vegetation cover, and soil (micro)biological communities. Warming also facilitates agricultural expansion, urban growth, and natural resource development, adding growing anthropogenic pressures to cold regions' landscapes, soil health, and biodiversity. Further advances in the predictive understanding of how cold regions' critical zone processes, functions, and ecosystem services will continue to respond to climate warming and land use changes require multiscale monitoring technologies coupled with integrated observational and modeling tools. We highlight some of the major challenges, knowledge gaps, and opportunities in cold region critical zone research, with an emphasis on subsurface processes and responses in both natural and agricultural ecosystems.

The Cold Region Critical Zone in Transition: Responses to Climate Warming and Land Use Change

Article

Full-text available

Oct 2021

Global climate warming disproportionately affects high-latitude and mountainous terrestrial ecosystems. Warming is accompanied by permafrost thaw, shorter winters, earlier snowmelt, more intense soil freeze-thaw cycles, drier summers, and longer fire seasons. These environmental changes in turn impact surface water and groundwater flow regimes, water quality, greenhouse gas emissions, soil stability, vegetation cover, and soil (micro)biological communities. Warming also facilitates agricultural expansion, urban growth, and natural resource development, adding growing anthropogenic pressures to cold regions’ landscapes, soil health, and biodiversity. Further advances in the predictive understanding of how cold regions’ critical zone processes, functions, and ecosystem services will continue to respond to climate warming and land use changes require multiscale monitoring technologies coupled with integrated observational and modeling tools. We highlight some of the major challenges, knowledge gaps, and opportunities in cold region critical zone research, with an emphasis on subsurface processes and responses in both natural and agricultural ecosystems. Expected final online publication date for the Annual Review of Environment and Resources, Volume 46 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Leaching of trace metals (Pb) from contaminated tailings amended with iron oxides and manure: New insight from a modelling approach

Article

May 2021
CHEM GEOL

Reclamation measurements are commonly applied to mitigate the leaching of metal pollutants in order to reduce the risk for humans and the environment. The stabilization of mine tailings can be performed by amending with organic or inorganic materials. In a recent laboratory microcosm experiment (Thouin et al., 2019), the addition of a mining slurry called ochre and manure, either alone or in combination, drastically reduced the leaching of several metal pollutants, notably Pb. Nevertheless, the biogeochemical processes involved in the immobilization of metal pollutants remain unknown, preventing the management of this remediation technique from being optimized and its extension to other sites. To fill this gap, a multicomponent mixing model was developed to simulate and forecast the impact of amendments on the leaching of metal pollutants. This model accounts for the following biogeochemical processes: kinetically-controlled dissolution/precipitation reactions, sorption reactions (i.e. surface complexation reactions), water-gas interactions and microbial respiration with an explicit microbial growth. For all treatments, simulations revealed that Pb reactivity followed dynamic patterns driven by watering steps. The decrease in Pb concentration in the leachates of amended tailings compared to untreated tailings was also accurately reproduced. In untreated tailings, Pb reactivity is mainly controlled by the dissolution of Pb-bearing mineral phases. These reactions were maintained in thermodynamic disequilibrium due to the renewal of pore solution at each watering step. In amended tailings, this pattern was strengthened as the iron oxides contributed by ochre maintained a low Pb concentration in pore solution by sorbing released Pb. Sorption reactions were enhanced by the increase in pH induced by the dissolution of calcium carbonate initially present in ochre. The latter reaction was partially counterbalanced in tailings amended with manure as organic matter provided sufficient energy to fuel microbial aerobic respiration, leading to the release of protons. Pb desorption was promoted by this pH drop. The magnitude of these reactions was not strictly proportional to the amount of manure added. For 0.15% by weight, aerobic respiration did not occur whereas its yield was similar for 1% and 2%. By providing a better understanding of the effect of amendment, this multicomponent mixing model is a powerful tool to optimize the reclamation of tailings, in order to limit contaminant transfer to the environment.

Priming effect of stable C pool in soil and its temperature sensitivity

Article

Nov 2021
GEODERMA

It is important to understand the effects of exogenous carbon (C) additions on the mineralization of native soil C in agricultural soils under changing global temperatures. The slowly mineralizable C pools represent the major component of soil carbon. Once the labile fraction of soil C is depleted through mineralization, additions of exogenous labile C may enhance decomposition of slowly mineralizable soil C through the so-called priming effect (PE). The effect of exogenous C on mineralization of slowly mineralizable C in soils that have undergone extended substrate depletion is not well understood. The aim of this study was to assess the effects of exogenous C addition on the PE and its temperature sensitivity (Q10) in two substrate depleted soils. The Mollisols with two levels of C 6.8% and 2.9% were pre-incubated at 15 and 25 ℃ for 864 days, followed by 42-day incubations with and without ¹³C-enriched corn (Zea mays) leaf addition at 15 and 25 ℃. Soil organic carbon (SOC) decreased by 7%−9% in low and 1%−3% in high C soil after the long-term pre-incubation, respectively. In the 42-day incubation following the long-term pre-incubation, the incubation at the higher temperature (25 ℃) significantly increased cumulative CO2 production compared to that at the lower temperature (15 °C) for both high and low C soils with or without exogenous C addition. Furthermore, corn leaves addition stimulated CO2 production derived from resistant OC in both soils, resulting in a positive PE. Higher incubation temperature resulted in a greater PE in both soils independent of pre-incubation temperature. The temperature sensitivity (Q10) of the PE in the low C soil pre-incubated at 25 °C was greater than that pre-incubated at 15 °C, but in the high C soil, the Q10 of PE was lower after pre-incubation at 25 °C. The results confirmed that exogenous C addition and a higher temperature accelerate native SOC mineralization and suggested that the temperature sensitivity of the PE depended on the soil C content and the long-term temperature regime a soil is subjected to.

Warming and straw application increased soil respiration during the different growing seasons by changing crop biomass and leaf area index in a winter wheat–soybean rotation cropland

Article

Feb 2021
GEODERMA

Warming and straw application are two important factors that may influence soil respiration. Investigations of the different effects of warming and straw application on soil respiration during different crop growing seasons are crucial to understand the soil carbon (C) cycles in croplands under future climate scenarios. A two-year field experiment was performed in a winter wheat-soybean cropland in subtropical east China to investigate the different effects of 1.4 °C warming and straw application on soil respiration. There were two main plots, i.e., warming and unwarmed treatments, with three straw application levels: no straw applied, low straw application (6 t ha⁻¹) and high straw application (12 t ha⁻¹) in each treatment. Seasonal variations in soil respiration, soil temperature, soil moisture and leaf area index (LAI) were measured. The results indicated that both warming and straw application significantly increased soil respiration during each growing season. Compared with the unwarmed treatment, warming increased soil respiration by 24.7%, 12.1%, and 12.6% in the plots with no straw applied, low straw application and high straw application, respectively, during the 2017–2019 rotation period. The mean soil respiration during the two-year rotation was significantly (P < 0.01) correlated with root biomass, stem and shoot biomass, grain yield, and LAI. The soil temperature, moisture and LAI-based model accounted for 57.9%-69.1% of the seasonal variation in soil respiration in all treatments. The positive effects of warming and straw application on soil respiration were related more to the variations in crop biomass and LAI than those in grain yield.

Plastic film mulching mitigates the straw-induced soil greenhouse gas emissions in summer maize field

Article

Jun 2021
APPL SOIL ECOL

The positive impact of straw incorporation (S1) on mitigating global warming potential due to increase soil organic carbon sequestration can be offset by the straw-induced greenhouse gas (GHG) emissions. Therefore, this study advocated an optimal straw-based system, i.e. straw incorporation plus half plastic film mulch (SP), to mitigate the straw-induced GHG emissions in northwest China. A two-year field experiment was conducted to investigate effects of no straw inputs (S0), S1 and SP on yields, GHG emissions and soil labile carbon (C) and nitrogen (N) pools, and identify the relationship between GHG emissions and soil labile C and N pools. Results showed that SP significantly enhanced maize yield by 14.5 and 7.0% in 2018 and 2019, respectively, as compared to S0, mainly due to the increased soil inorganic nitrogen (SIN) and dissolved organic nitrogen (DON) contents. In addition, SP considerably mitigated the straw-induced CO2 emission by 77.8 and 67.1% in 2018 and 2019, respectively, mainly attributed to the reduced dissolved organic carbon (DOC)/DON, microbial biomass carbon (MBC)/SIN and DOC/SIN. Moreover, SP significantly lessened the straw-induced N2O emission by 43.6 and 59.5% in 2018 and 2019, respectively, due to significant decreased DOC content during seeding to jointing, the major N2O emission period. Our results indicated that SP, as a kind of straw-based system, enhanced the sustainability of summer maize ecosystem because of mitigating the straw-induced GHG emissions and simultaneously enhancing maize yield.

Soil CO2 and CH4 concentration dynamics and their relationships with soil physicochemical properties, soil enzyme activity, and root biomass under shallow groundwater level

Preprint

Nov 2020

Soil CO2 and CH4 concentrations are crucial determinants of crop physiology and soil environment. This study aimed to investigate the dynamics of soil CO2 and CH4 concentrations and their correlations with soil nutrient content, enzymatic activities and root biomass at shallow groundwater levels. Lysimeter experiments were conducted at five groundwater depths (20, 40, 50, 60, and 80 cm) and three fertilizer application rates (low, 75%; normal, 100%; high, 125%). Soil CO2 and CH4 concentrations, physicochemical properties, and enzymatic activities were determined in the three growth stages of winter wheat crop, and plant biomass was measured post-harvest. Groundwater depth significantly (P ≤ 0.001) affected CO2 and CH4 concentrations and root parameters, and their critical values appeared at the groundwater depth of 50–60 cm. Soil water content presented quadratic function relation with CO2 concentration, and exhibited the linear correlation with CH4 concentration. As an aerobic respiration product, soil CO2 concentration showed significant positive correlations with organic matter and total N levels, urease, phosphatase and sucrase activities, and root biomass in winter wheat. Soil CH4 concentration depending on anaerobic microbial activity showed significant correlations with soil nutrients, such as soil organic matter, total N, and available K. Fertilization significantly impacted root parameters (P ≤ 0.001) and shoot biomass (P ≤ 0.05) instead of CO2 and CH4 concentrations. In contrast, groundwater depth emerged as a crucial factor as it affected soil physicochemical properties, soil enzymatic activities, root respiration, and winter wheat growth at shallow groundwater levels.

Integrated Weed and Nutrient Management Improve Yield, Nutrient Uptake and Economics of Maize in the Rice-Maize Cropping System of Eastern India

Article

Full-text available

Dec 2020

ncreasing productivity of maize while decreasing production costs and maintaining soil health are emerging challenges for the rice–maize system in South Asia. A range of integrated nutrient and weed management practices were tested in winter maize for their effects on yield, profitability, and soil health. The nutrient management treatments were a partial substitution of nitrogen with bulky (Farmyard manure; vermicompost) and concentrated organic manures (Brassicaceous seed meal, BSM; neem cake), whereas weed management practices compared chemical controls only versus an integrated approach. The N supplementation through BSM diminished the weed growth by reducing weed N uptake, and enhanced the maize crop uptake of nutrients. As compared to the sole chemical approach, atrazine-applied pre-emergence followed by hoeing reduced weed density by 58 and 67% in years 1 and 2, respectively. The N supplementation through BSM resulted in the maximum yield of maize grain (6.13 and 6.50 t ha−1 in year 1 and year 2, respectively) and this treatment increased yield in year 2 compared to N application through synthetic fertilizer. Hoeing in conjugation with herbicide enhanced the maize grain yield by 9% over herbicide alone. The maximum net return and economic efficiency were achieved with the application of BSM for N supplementation, together with the integrated weed management practice.

Integrated Weed and Nutrient Management Improve Yield, Nutrient Uptake and Economics of Maize in the Rice-Maize Cropping System of Eastern India

Article

Full-text available

Dec 2020

Increasing productivity of maize while decreasing production costs and maintaining soil health are emerging challenges for the rice-maize system in South Asia. A range of integrated nutrient and weed management practices were tested in winter maize for their effects on yield, profitability, and soil health. The nutrient management treatments were a partial substitution of nitrogen with bulky (Farmyard manure; vermicompost) and concentrated organic manures (Brassicaceous seed meal, BSM; neem cake), whereas weed management practices compared chemical controls only versus an integrated approach. The N supplementation through BSM diminished the weed growth by reducing weed N uptake, and enhanced the maize crop uptake of nutrients. As compared to the sole chemical approach, atrazine-applied pre-emergence followed by hoeing reduced weed density by 58 and 67% in years 1 and 2, respectively. The N supplementation through BSM resulted in the maximum yield of maize grain (6.13 and 6.50 t ha −1 in year 1 and year 2, respectively) and this treatment increased yield in year 2 compared to N application through synthetic fertilizer. Hoeing in conjugation with herbicide enhanced the maize grain yield by 9% over herbicide alone. The maximum net return and

Sensitivity of the DSSAT model in simulating maize yield and soil carbon dynamics in arid Mediterranean climate: Effect of soil, genotype and crop management

Article

Full-text available

Jan 2021
FIELD CROP RES

Crop models may potentially explore alternative ways to improve agroecosystem resilience in arid regions of Middle East and North Africa. Mapping the outputs behavior as a function of the inputs and quantifying the uncertainty contribution of inputs to the variability of outputs are crucial for understanding and applying complex mathematical models to a new environment. Objectives of present research are (i) to calibrate and evaluate the Decision Support System for Agrotechnology Transfer (DSSAT) cropping system model using detailed experimental datasets on maize production in arid sandy soils (Entisol) and (ii) to determine the model's sensitivity to soil, genotype and crop management inputs under the currently explored conditions (low fertility and water holding capacity) based on multivariate analysis and variance decomposition methods. The goodness-of-fit statistics between observed and simulated data indicated that the calibrated model reasonably well simulates maize phenology, growth and yield, evapotranspiration, soil water content, grain N concentration, and postharvest soil NO 3-N in eight year site field experiments. A global sensitivity analysis using the co-inertia method was carried out to link 14 output variables and 25 soil and genotype input parameters. Maize growth and yield variables were strongly correlated with soil hydrological and fertility input parameters such as soil water upper limit (SDUL) and soil organic carbon (SOC), whereas simulation of maize phenology was largely determined by phenological genotype-specific cultivar input parameters. A strong association was also observed between the output variables of yield and soil fertility. The effect of carbon (C) related soil input parameters of initial SOC and stable SOC and crop management factors of maize residue retention and compost application under no-till system on the long-term (10 years) simulation of yield and SOC dynamics was further explored using Sobolʹ method. Simulated grain yield, water productivity, active SOC, and cumulative soil CO 2 efflux were most sensitive to initial stable SOC and compost application. Maize residue retention significantly affected the simulation of cumulative N mineralization, SOC % in 0.2 m depth, and cumulative soil CO 2 efflux through interactions effect, i.e. total-order sensitivity index (S Ti) > 0.05, with other inputs. Compost application increased grain yield by 13 %, SOC stock by 5%, and cumulative soil CO 2 efflux by 95 % compared with no application. However, compost application with maize residue retained significantly reduced cumulative soil CO 2 efflux by 12 % compared with compost application with maize residue removed. Therefore, the application of compost with maize residue retained under no-till system is a plausible crop management option for agronomically improved and environmentally sound maize production in arid sandy soils.

How do greenhouse gas emissions vary with biofertilizer type and soil temperature and moisture in a tropical grassland?

Article

Oct 2020
PEDOSPHERE

Greenhouse gases are known to play an important role in global warming. In this study, we determined the effects of selected soil and climate variables on nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2) emissions from a tropical grassland fertilized with chicken slurry, swine slurry, cattle slurry, and cattle compost. Cumulative N2O emissions did not differ between treatments and varied from 29.26 to 32.85 mg N m⁻². Similarly, cumulative CH4 emissions were not significantly different among the treatments and ranged from 6.34 to 57.73 mg CH4 m⁻². Slurry and compost application induced CO2 emissions that were significantly different from those in the control treatment. The CH4 conversion factors measured were 0.21%, 1.39%, 4.39%, and 5.07% for cattle compost, chicken slurry, swine slurry, and cattle slurry, respectively, differing from the recommendations of the Intergovernmental Panel on Climate Change (IPCC). The fraction of added N emitted as N2O was 0.39%, which was lower than the IPCC default value of 2%. Our findings suggest that N2O emissions could be mitigated by replacing synthetic fertilizer sources with either biofertilizer or compost. Our results indicate the following: N2O emission was mainly controlled by soil temperature, followed by soil moisture and then soil NH4⁺ content; CH4 fluxes were mainly controlled by soil moisture and chamber headspace temperature; and CO2 fluxes were mainly controlled by chamber headspace temperature and soil moisture.

Effect of Nitrogen Fertilizer on Soil CO2 Emission Depends on Crop Rotation Strategy

Article

Full-text available

Jun 2020

Developing environmentally friendly and sustainable nitrogen (N) fertilizer management strategies is crucial in mitigating carbon dioxide (CO2) emission from soil. How N fertilizer management practices influence soil CO2 emission rates under different crop rotations remains unclear. The aim of this study was to assess the impact on soil CO2 emission and soil physicochemical properties of three N fertilizer treatments including traditional rate (TF), optimized rate (0.8TF), and no fertilizer (NF) under three different crop rotation treatments: wheat-fallow (WF), wheat-soybean (WS), and wheat-maize (WM) over two years in a field experiment in northwest China. The rates were 5.51, 5.60, and 5.97 μmol·m−2·s−1 of mean soil CO2 emission under the TF, 0.8TF, and NF treatments, respectively. Mean soil CO2 emission rates were 21.33 and 26.99% higher under the WM rotation compared with the WF and WS rotations, respectively. The WS rotation showed higher soil nutrient content and lower soil CO2 emissions, and reduced fertilizer application. Importantly, soil organic carbon (SOC) concentration in the topsoil can be maximized by including either a summer legume or a summer maize crop in winter wheat rotations, and by applying N fertilizer at the optimal rate. This may be particularly beneficial in the dryland cropping systems of northern China.

Impact of long-term chemical fertilizer and organic amendment to Fusarium root rot of soybean

Article

Full-text available

May 2020

Soil suppressiveness to Fusarium root rot of soybean had been observed in a black soil field after a long-term fertilization with nitrogen (N) and phosphorus (P) fertilizer combined with pig manure as organic amendment (NPM), rather than that with only nitrogen and phosphorus fertilizer (NP) or no fertilizer (NF). To determine the microbial role on this suppressiveness, fungal and bacterial community characteristics in NPM, NP and NF were investigated by qPCR and DGGE. Compared with the similar bacterial community characteristics among 3 treatments, fungal community, especially Fusarium population size and community composition in NPM were different with those of NP and NF. Based on the isolation and pathogenicity test, pathogenic F. oxysporum, F. graminearum, F. verticillioide and F. lateritium absolutely dominated Fusarium community in NF and NP. Nonpathogenic F. avenaceum, F. equiseti, F. culmorum, F. redolens, F. solani and F. tricinctum dominated Fusarium community in NPM. Isolation rate of pathogenic Fusarium in NPM reduced from 100% to 38% in NF. These results suggested that the dominance of soil non-pathogenic Fusarium population induced by organic amendment might play an important role on suppressing Fusarium root rot in the tested soil.

Soil CO2 emission in response to organic amendments, temperature, and rainfall

Article

Full-text available

Apr 2020

Vegetated land surfaces play an important role in determining the fate of carbon in the global carbon cycle. However, our understanding of the terrestrial biosphere on a global scale is subject to considerable uncertainty, especially concerning the impacts of climatic variables on the carbon cycle. Soil is a source and also a sink of CO2 exchange and helps in carbon sequestration. Agricultural management practices influence soil water dynamics, as well as carbon cycling by changing soil CO2 emission and uptake rates. The rate of soil CO2 emission varies for different crops and different organic amendments. The major goal of this study was to assess the impacts of the type and rate of organic amendment on soil CO2 emission in a collard greens crop grown in the southeast Texas environment. Thirty-six plots were developed to grow collard greens on Prairie View A&M University’s Research Farm. Three types of organic amendments (Chicken manure, Dairy manure, and Milorganite), at four levels of application (0, 168, 336, and 672 kg N/ha) were used and replicated three times. Each organic amendment type was applied to nine randomly selected plots. Three random plots were used as a control in each row. We measured daily soil CO2 emission for the first two weeks and every other day in a week during the experiment. We evaluated the effects of organic amendments and the application rates on soil CO2 emission for collard greens during two growing seasons. The results showed higher the application rates for each organic amendment, higher the CO2 emissions from the soil. The results also showed higher cumulative CO2 emissions for the soils amended with chicken manure and milorganite, but lowest for the soils amended with dairy manure. This field experiment and analyses help better understand the temporal and spatial variations of soil CO2 emission, and also help to develop best management practices to maximize carbon sequestration and to minimize soil CO2 emissions during the growth periods of collard greens under changing temperatures using different organic amendments, and application rates.

Valorization of agricultural wastes could improve soil fertility and mitigate soil direct N2O emissions

Article

Sep 2019

The emerging need for sustainable management of the increasing quantities of urban and industrial organic wastes creates opportunities for the development of alternative strategies for the improvement of degraded soils. The current study was performed to examine the effects of agricultural wastes application on soil bacterial community as well as CO2 and N2O direct gas emissions. Untreated soils were compared with soils, which received the same amount of N (100 μg/g soil) in the form of ammonium nitrate and organic agricultural waste. In particular, soils were incubated with three different organic agricultural wastes, orange (OP), mandarin (MP) and banana peels (BP) and ammonium nitrate (F) after adjusting soil water at 70% of its holding capacity. In the current study, soil chemical characteristics, quantitative PCR of denitrifiers (nirK, nirS, nosZI and nosZII) and16s rRNA amplicon sequencing were assessed to examine the links between the soil microbial communities and short-term soil direct N2O emissions when treated with agricultural wastes. The highest soil direct N2O emissions were recorded in soils received ammonium nitrate while soils received agricultural wastes exhibited substantially lower soil direct N2O emissions. On the contrary, agricultural wastes stimulated CO2 accumulation as well as the growth of copiotrophic bacterial groups like Proteobacteria and Firmicutes. Interestingly, direct soil N2O emissions were decoupled from the density of denitrifier community while agricultural wastes caused a substantial reduction of the relative abundance of bacterial taxa associated with N2O emissions in the soil. This study proves evidence that agricultural wastes could be integrated in a waste management strategy, which inter alia includes their direct use in agricultural ecosystems resulting in reduced N2O emissions.

İmanverdi Ekberli, Yıldız Sarılar, 2014. INVESTIGATING SOIL TEMPERATURE VARIABILITY AND THERMAL DIFFUSIVITY IN GRASS COWERED AND SHADED AREAS BY TREES

Article

Full-text available

Jan 2014

İmanverdi Ekberli, Yıldız Sarılar, 2014. INVESTIGATING SOIL TEMPERATURE VARIABILITY AND THERMAL DIFFUSIVITY IN GRASS COWERED AND SHADED AREAS BY TREES

Article

Full-text available

Jan 2014

Soil respiration may be reduced by wind via the suppressing of root respiration: Field observation in maize farmland in the agro-pastoral transitional zone, northeastern China

Article

Feb 2023
ECOL INDIC

Soil respiration is a major source of atmospheric carbon dioxide (CO2). Intensive exploring on soil respiration in farmland may provide important information for controlling CO2 emissions. However, some important meteorological factors, especially for the wind, have been neglected previously. In this two-season field observation, we measured soil total respiration (Rt) in maize farmland in an agro-pastoral transitional zone in northeastern China, including autotrophic (root) respiration (Ra) and heterotrophic respiration (Rh), using the root-exclusion method. The mean Rt was 4.0 ± 0.8 and 6.1 ± 1.4 μmol·m⁻²·s⁻¹ in the two growing seasons. The root contribution to the total soil respiration rate (Rc) was 55.5 and 44.1 %, respectively, and both followed an approximately unimodal curve as a function of day of year. Ra and Rh were both positively correlated with the soil temperature. Ra decreased with increasing wind speed, but Rh was not significantly affected; thus, Rc was negatively correlated with the wind speed. The decrease of Rc caused by increased wind speed differed among the growth stages. Significant suppression of Rc was detected at the jointing stage and at maturity. Responses of Rt and its components to meteorological factors differed significantly in magnitude between the day and night. However, Rc decreased with increasing wind speed both during the day and at night. In summary, the decrease of farmland soil respiration by the wind resulted from decreased root respiration and could be regulated by the modifying of artificial windbreaks or by the expanding of row space of the maize planting, thereby reducing carbon dioxide emission. Indeed, this study is only the observation and analysis of some traditional factors, more intensive observations, especially evidence from physiological traits, morphological anatomy and other perspectives are required to confirm this relationship in further studies.

Straw return and nitrogen fertilization regulate soil greenhouse gas emissions and global warming potential in dual maize cropping system

Article

Aug 2022
SCI TOTAL ENVIRON

Abundant nitrogen (N) fertilization is needed for maize (Zea mays L.) production in China because of its huge residual biomass return. However, excessive N fertilization has a negative impact on the soil ecosystem and environment, which contributes to climate change. Soil incorporation of maize residues is a well-known practice for reducing chemical N fertilization without compromising maize yield and soil fertility. Thus, residues incorporation has the capacity to minimize N fertilization uses and hence mitigate soil greenhouse gas emissions by improving plant N uptake and use efficiency. There is still a research gap regarding the effects of maize residues incorporation on maize yield, soil fertility, greenhouse gas emissions, and plant N and carbon (C) contents. Therefore, we conducted a field experiment during spring and autumn involving four different N fertilization rates (N0, N200, N250, and N300 kg N ha⁻¹), with and without maize residues incorporation, to evaluate grain yield, soil fertility, plant N and C contents, and greenhouse gas emissions (GHGs). Compared to N0, N fertilizer application at 300 kg N ha⁻¹ with residues incorporation significantly increased area-scaled global warming potential (GWP) compared to other N fertilization rates in both spring and autumn seasons, but soil nutrient contents and plant N and C contents were not statistically different from the N250 treatment. In contrast, the N recovery use efficiency (NRUE), physiological N use efficiency (PNUE), and agronomic N use efficiency (ANUE) were significantly lower in the N300 treatment than in the lower N treatment groups. Nitrous oxide (N2O) and carbon dioxide (CO2) fluxes, area-scaled GWP, and greenhouse gas intensity (GHGI) were significantly lower in the N200 treatment with straw incorporation than the N250 and N300 treatments of the traditional planting system. Thus, we concluded that N200 treatment with residues incorporation is optimal for improving grain yield, soil fertility, plant N uptake, and mitigating greenhouse gas emissions.

Responses of soil greenhouse gas emissions to land use conversion and reversion — A global meta‐analysis

Article

Aug 2022

Exploring the responses of greenhouse gases (GHGs) emissions to land use conversion or reversion is significant for taking effective land use measures to alleviate global warming. A global meta‐analysis was conducted to analyze the responses of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions to land use conversion or reversion, and determine their temporal evolution, driving factors and potential mechanisms. Our results showed that CH4 and N2O responded positively to land use conversion while CO2 responded negatively to the changes from natural herb and secondary forest to plantation. By comparison, CH4 responded negatively to land use reversion and N2O also showed negative response to the reversion from agricultural land to forest. The conversion of land use weakened the function of natural forest and grassland as CH4 sink and the artificial nitrogen (N) addition for plantation increased N source for N2O release from soil, while the reversion of land use could alleviate them to some degree. Besides, soil carbon would impact CO2 emission for a long time after land use conversion, and secondary forest reached the methane uptake level similar to that of primary forest after over 40 years. N2O responses had negative relationships with time interval under the conversions from forest to plantation, secondary forest and pasture. In addition, meta‐regression indicated that CH4 had correlations with several environmental variables, and carbon‐nitrogen ratio had contrary relationships with N2O emission responses to land use conversion and reversion. And the importance of driving factors displayed that CO2, CH4 and N2O response to land use conversion and reversion were easily affected by NH4+ and soil moisture, mean annual temperature and NO3‐, total nitrogen and mean annual temperature, respectively. This study would provide enlightenments for scientific land management and reducing of GHG emissions.

Devenir de contaminants métalliques (Pb, Zn) depuis un dépôt minier ancien : développement d'un modèle de transport réactif

Thesis

Dec 2021

Samuel Mertz

Cette thèse s'inscrit dans le cadre de la gestion des anciens sites miniers contaminés en métaux et de leur effet sur l'environnement. L'objectif de cette thèse réside dans la détermination et la hiérarchisation des processus régulant le transfert des métaux au sein de résidus miniers anciens, via le développement d’un modèle de transport réactif (RTM). Premièrement, un modèle biogéochimique a été construit pour définir les processus contrôlant la mobilité de Pb/Zn issus de résidus miniers. Ce modèle a été développé via des données expérimentales de lixiviation en microcosmes acquises d’une précédente étude, impliquant plusieurs traitements : (1) résidu seul, (2) ajout de boue minière, (3) ajout de boue minière et de fumier. Les résultats ont montré que les processus de dissolution des phases porteuses contrôlaient la libération de Pb/Zn. L’ajout de boue minière favorise l’immobilisation des métaux à travers l’apport d’oxydes de fer sur lesquels le Pb/Zn s’adsorbe. L’ajout de fumier, en amplifiant la respiration microbienne et la production de CO2, favorise la baisse du pH et la désorption de Pb/Zn. Deuxièmement, un RTM a été développé comprenant : (1) une description mécaniste des processus biogéochimiques et (2) l’écoulement et le transport des solutés dans un milieu 1D à saturation variable. Il se base sur des données d’expériences de lixiviation sur une colonne métrique instrumentée, avec ou sans amendement. Les résultats ont montré une similarité des processus contrôlant de la mobilité du Pb/Zn entre les microcosmes et la colonne métrique. Le devenir à long-terme des résidus miniers a pu être évalué, sans amendement la libération de Pb/Zn ne s’achèvera pas avant 100 ans. Les résidus amendés présentent néanmoins une immobilisation durable de Pb/Zn.

Nitrogen fertilization decrease soil CO2 emission in a rainfed maize field in Northeast China

Article

Full-text available

Jun 2022
ENVIRON SCI POLLUT R

Nitrogen fertilizer has considerable effects on soil carbon fluxes. However, the responses of soil CO2 emission to N fertilizer remain controversial. A field experiment was conducted to examine the effect of application of N fertilizer on soil CO2 emission in a maize (Zea mays L.) field in Northeast China. Soil CO2 emission was measured from May 2010 to April 2016. Soil CO2 emission during the growing season and non-growing season contributed 79.7–83.6% and 16.4–20.3%, respectively, to the total annual CO2 emission. Cumulative annual soil CO2 emissions were significantly higher in no-N addition treatment (CK) than that in N addition treatment (SU) from 2012/2013 to 2015/2016 (p < 0.05). Mean annual soil CO2 emission decreased on averaged by 21.2% after N fertilization (p < 0.05). 49.6–82.2% of CO2 flux variation was explained by soil temperature at 5 cm depth. Q10 of soil CO2 emission in the annual scale was not significantly affected by N fertilizer. The results highlight the importance of N fertilizer on soil CO2 emission in agricultural ecosystem.

Long-Term Phosphorus Addition Strongly Weakens the Carbon Sink Function of a Temperate Peatland

Article

Full-text available

Mar 2022
ECOSYSTEMS

Peatlands are important nutrient-limited, carbon (C)-accumulating ecosystems where phosphorus (P) is one major limiting nutrient. An increase in P input to peatlands has been observed close to agricultural areas. However, the effects of P input on gross primary productivity (GPP), ecosystem respiration (ER) and net ecosystem exchange (NEE) of peatlands, especially in temperate Asia, have been rarely studied. We selected the P addition plots of a 12-year experiment simulating environmental change in a peatland in northeastern China to evaluate the effect of P addition (5 and 10 kg ha⁻¹ y⁻¹) on carbon dioxide fluxes. Our results showed that the growth of Sphagnum was inhibited but that of vascular plants was facilitated by P addition, resulting in an unchanged GPP. P addition increased ER due to the increased activity potentials of N-acetyl-β-glucosaminidase (NAG) and polyphenol oxidase (POX) that might, in turn, increase the metabolic rate of soil microbes and enhance the decomposition of peat. During the growing season, a mean net CO2 absorption of 0.002 mg m⁻² s⁻¹ was observed at high levels of P addition, which was much lower than that of 0.063 mg m⁻² s⁻¹ in the controls. The results suggest that long-term P addition will greatly weaken the C sequestration in peatlands by enhancing ER rather than reducing GPP. Our study highlights the importance of the response of vegetation and soil enzyme activities to P addition regarding peatland respiration and C sink function.

Biochar rather than organic fertilizer mitigated the global warming potential in a saline-alkali farmland

Article

May 2022
SOIL TILL RES

A 3-year field study was conducted to examine the effects of continuous application of biochar and organic fertilizer on global warming potential (GWP) and greenhouse gas intensity (GHGI) as well as crop yield in a saline-alkali farmland of northern China. Six treatments were included: 1) control (only chemical fertilizer with N200 kg ha⁻¹ yr–1 and P2O5 120 kg ha⁻¹ yr–1, CK); 2) biochar at 5.0 t ha–1 yr–1 (C1); 3) biochar at 10.0 t ha–1 yr–1 (C2); 4) biochar at 20.0 t ha–1 yr–1 (C3); 5) organic fertilizer at 7.5 t ha–1 yr–1 (M1); and 6) organic fertilizer at 10.0 t ha–1 yr–1 (M2). Biochar and organic fertilizer treatments were adjusted to the same N and P level as the control by supplemented urea and diammonium phosphate. The results showed that both biochar and organic fertilizer reduced the annual average emissions of CH4, N2O and ecosystem respiration (Re), but the emissions from the biochar treatments were lower than those from the organic fertilizer treatments. Biochar but not organic fertilizer increased the maize and wheat yields. Both biochar and organic fertilizer increased the soil carbon (C) storage and the net ecosystem carbon budget (NECB). The ΔSOCs of biochar and organic fertilizer treatments were increased by 9.1%–16.5% and 5.0%–5.8%, respectively, compared with the control (1.21 t C ha⁻¹ yr⁻¹). The mean annual net GWPs of biochar and organic fertilizer treatments were decreased by 282.5%–365.0% and 89.2%–110.0%, respectively, compared with the control (1.2 t CO2-eq ha⁻¹ yr⁻¹). The GHGIs were decreased by 266.7%–344.4% and 88.9%–110.0%, respectively, compared with the control (0.09 t CO2-eq ha⁻¹ yr⁻¹). The net GWPs and GHGIs were significantly lower in the C2 and C3 than other treatments, but there was no significant different between C2 and C3. The N2O emissions and ΔSOC contributed greatly to the net GWP, therefore, controlling soil N2O emissions and increasing soil C storage are key components of reducing net GWP and GHGI. In conclusion, application of biochar is an effective agricultural practice to improve soil quality, increase crop yield and reduce greenhouse gases (GHGs) emissions in the saline-alkali soil of northern China.

Manejo nutricional integrado: herramienta clave para la agricultura sostenible

Article

Full-text available

Aug 2021

El principal reto que enfrenta la agricultura es satisfacer la creciente demanda mundial de alimentos y al mismo tiempo reducir el impacto agrícola ambiental negativo. La nutrición de los cultivos depende principalmente de los fertilizantes minerales, lo cual es una amenaza para el medio ambiente y para la salud humana. Una alternativa para solventar esta problemática es el manejo nutricional integrado con fertilizantes minerales y abonos orgánicos para disminuir el uso de los fertilizantes minerales al tiempo que se favorece la productividad de los cultivos, así como la calidad de los productos agrícolas y del medio ambiente. La presente revisión recopila resultados de investigaciones enfocadas al manejo nutricional integrado, como parte del funcionamiento holístico de los agroecosistemas, en varios ámbitos: a) calidad del suelo; b) productividad y rentabilidad de los cultivos; c) calidad de los productos agrícolas; d) emisión de gases de efecto invernadero; y e) transferencia de nitrógeno al agua.

One-Pot Facile Synthesis of Double-Shelled Mesoporous Silica Microcapsules with an Improved Soft-Template Method for Sustainable Pest Management

Article

Aug 2021

Does biochar accelerate the mitigation of greenhouse gaseous emissions from agricultural soil? - A global meta-analysis

Article

Jul 2021
ENVIRON RES

Greenhouse gaseous (GHGs) emissions from cropland soils are one of the major contributors to global warming; however, the extent and pattern of these climatic breakdowns are typically determined by the management practices in-place. The use of biochar on cropland soils holds a great promise for increasing the overall crop productivity. However, biochar applications to agricultural soil has grown in popularity as a strategy to off-set the negative feedback associated with agriculture GHGs emissions i.e., CO2 (carbon dioxide), CH4 (methane), and N2O (nitrous oxide). Despite increased efforts to uncover biochar's potential for mitigating the farmland GHG effects, there has been little synthesis of how different types of biochar influence cropland soil GHG fluxes under varied experimental conditions. Here, we presented a meta-analysis of biochar-GHG emissions interactions across global cropland soil, with field experiments showing the strongest GHG mitigation potential i.e., CO2 (RR = -0.108), N2O (RR = 0.11), and CH4 (RR = -0.399). The biochar pyrolysis temperature, feedstock, C: N ratio, and pH were also found to be important factors influencing GHGs emissions. A prominent reduction in N2O (RR = -0.13) and CH4 (RR = -1.035) emissions was observed in neutral soils (pH = 6.6-7.3), whereas acidic soils (pH ≤ 6.5) accounted for the strongest mitigation effect on CO2 (RR = 0.12) emissions. We also discovered that a biochar application rate of 30 t ha-1 was best-suited for mitigating GHGs emissions while maintaining optimum crop yield. According to our meta-analysis, maize crop receiving biochar amendment showed a significant mitigation potential for CO2, N2O, and CH4 emission. On the other hand, the use of biochar had shown significant impact on the global warming potential (GWP) of total GHGs emissions. The current data synthesis takes the lead in analyzing emissions status and mitigation potential for three of the most common GHGs from cropland soils and demonstrates that biochar application can significantly reduce the emissions budget from agriculture.

Long-term organic and inorganic fertilization on economics, energy budgeting and carbon footprint of soybean-wheat cropping system in the Indian mid-Himalayas

Article

Jul 2021

For identification and adoption of improved and environmental friendly agricultural practices with minimum emission of greenhouse gases (GHGs), observations were recorded for 3 years (2015–17) in a 22-year-old soybean-wheat based long-term fertilizer experiment that was started in 1995–96. The study involved seven treatments: control (CK), organic manure (M), inorganic fertilizers (NPK), integrated (MNPK), only nitrogen (N), mineral fertilizers in both season (NPK+NPK) and nitrogen with organic manure (MN). MNPK significantly enhanced the system productivity (9.72 Mg ha⁻¹) with higher net return (3128 US$ha⁻¹) and benefit-cost ratio (1.64). Due to better energy output to inputs relation, total energy productivity and energy use efficiency were reported higher in MNPK (0.38 kg MJ⁻¹ and 4.76, respectively) followed by MN (0.34 kg MJ⁻¹ and 4.26, respectively) and M (0.32 kg MJ⁻¹ and 4.16, respectively). In contrast to C efficiency, C sustainability index and yield scaled carbon footprint (CFy), the spatial CO2-e emission (CFs) was found highest under MNPK (~5035 kg CO2-e ha⁻¹) followed by MN and NPK+NPK and lowest was recorded under control. In sum, long-term organic and inorganic fertilization simultaneously in soybean-wheat system may be a preferred strategy for improving soil productivity, profitability, energy use and environmental sustainability of Indian-mid-Himalayas.

Temperature, soil moisture, and microbial controls on CO2 and CH4 emissions from a permafrost peatland

Article

Jun 2021

Peatlands are significant carbon dioxide (CO2) sinks and methane (CH4) sources. In this study, we investigated changes in CO2 and CH4 emissions from topsoil (0–20 cm) and subsoil (20–40 cm) in a permafrost peatland, and the related soil microbial abundance in response to increasing temperature and soil water content by using an incubation experiment. Our results indicated that CO2 and CH4 emissions from the permafrost peatland are highly sensitive to temperature and soil water content. CO2 emissions from topsoil and subsoil at 15 °C were 3.36 and 2.74 times larger, respectively, compared to those at 5 °C under the field moisture condition, and were 1.70 times larger under the waterlogged treatment in both topsoil and subsoil. CH4 emissions from 0–20 and 20–40 cm soils at 15 °C were 34 and 83 times larger, respectively, than those at 5 °C under the original state and 17 and 32 times larger under the waterlogged treatment. These results indicated that CH4 emissions are more sensitive than CO2 emissions, and waterlogged conditions could decrease temperature sensitivity of CO2 and CH4 emissions. Microbial analyses showed that the cumulative emissions amount of CO2 positively correlated with bacterial, fungal, and methanotroph abundances. Positive relationships were observed between CH4 emissions and abundances of bacteria, fungi, and archaea. These findings suggested that changes in temperature and water content alter CO2 and CH4 emissions from permafrost peatlands through controlling abundances of soil bacteria, fungi, archaea, and methanotrophs. These variables bear importance in accurately estimating C emissions from permafrost peatlands. This article is protected by copyright. All rights reserved.

Soil amendments from recycled waste differently affect CO2 soil emissions in restored mining soils under semiarid conditions

Article

Full-text available

May 2021

Drylands affected by serious disturbances such as mining activities lose their vegetation cover and organic soil horizons, becoming CO2 emissions sources. Applications of organic amendments could be a good restoration solution that favours vegetation establishment and soil carbon sequestration; however, they are also associated with CO₂ emissions. Experimental plots with different organic amendments (sewage sludge, garden and greenhouse vegetable composts, and mixtures of both) and unamended soils were installed in a quarry in southeast Spain. The aim of this study was: i) to evaluate the magnitude and changes of in situ CO₂ emission from each experimental plot during a year and a half, and ii) to assess the effects of several physical–chemical (total organic carbon, total nitrogen, water retention, pH and electrical conductivity) and environmental parameters (moisture and temperature) in CO2 emissions. The results showed an initial CO2 emission (priming effect), produced from all restored plots just after the application of the organic amendment, which was significantly higher (P < 0.05) in soils with sewage sludge and their mixtures in comparison to vegetable compost. Garden compost had low emission rates, similar to soils without amendment and showed lower CO2 emission rates than the rest of the restoration treatments. Nevertheless, CO2 emissions decreased in each field campaign over time, showing that all restored soils had lower emissions than natural soils at the end of the sampled period. The different composition of organic amendments had a different effect on soil CO2 emissions. DistLM analysis showed that soil properties such as total organic carbon, total nitrogen, pH and soil moisture, associated with rainfall periods, strongly influenced CO₂ emissions, whereas temperature did not affect the CO2 flow. In conclusion, the compost from plant remains could serve better as treatment to restore degraded soils in drylands than sewage sludge because of its lower CO2 emissions and concomitant effect on climate warming and carbon balance. Keywords: organic amendments, soil CO₂ emissions, restored soil, priming effect, soil respiration, recycled wast

Effect of Anthropogenic Activities on the Rate of Soil CO2 Flux in the Dipterocarpus Forest Ecosystem of Northeast India

Chapter

May 2021

The aim of the present study is to study the effect of anthropogenic activities, i.e. burning and logging on the rate of soil CO2 flux and its relationship with the abiotic and the biotic factor in the Dipterocarpus forest of Northeast India. Rates of soil CO2 flux were found to be the highest in burnt and the lowest in logged forest site. Seasonally soil CO2 flux rate was found to be maximum in rainy season and minimum in winter season in all the study sites. Simple linear regression shows there is a strong positive relationship between soil CO2 flux and soil moisture, temperature, and soil organic carbon. Soil CO2 flux rate can be altered through different forest management practices such as harvesting, thinning, and burning to mitigate climate change.

Heterogeneous Catalysis for Chemical Fixation of CO2 via Carbonylation Reactions

Chapter

May 2021

One of the major constituents of greenhouse gases is carbon dioxide whose concentration in the atmosphere is increasing at an alarming rate due to the disorganized human activities. Therefore, capturing CO2 and utilizing it to make various value-added chemicals is regarded as a green transformation, which thereby balances the carbon footprint. In this chapter, the advances in CO2 as the C1 source by utilizing it as a carbonylating agent for important organic transformations for the synthesis of cyclic carbonate, substituted urea, cyclic urea, carbamates, glycerol carbonate and dimethyl carbonate are discussed. These products have a wide range of applications as specialty solvents, starting materials/intermediates for polymer, paint, agrochemicals, pesticides, herbicides and pharmaceutical industries. Also, a few products like dimethyl carbonate have potential applications as fuel additives. Although CO2 is thermodynamically and kinetically stable molecule, it can be activated by basic sites in the catalyst due to the electron deficiency of the carbonyl carbon at appropriate reaction condition. Various catalyst systems such as metal oxides, mixed metal oxides, supported metal oxides, metal-organic framework, bifunctional catalysts and importance of solvent have been highlighted and discussed in detail for the efficient production of these commercially important chemicals from CO2.

CO2 Conversion into Chemicals and Fuel: India’s Perspective

Chapter

May 2021

India has come up with many policies and programs to take action toward mitigation of carbon dioxide from the energy sector through rapid augmentation of renewable energy growth and energy efficiency improvement. However, there is also need to unify abatement and recycling measures like amplification of low-carbon technologies. Emissions from various industries can be captured and reused for the production of various value-added chemicals and fuels. This chapter briefly discusses all the chemical reactions which require carbon dioxide as a primary product, giving a brief detail of electrocatalytic and photocatalytic pathways in which the anthropogenic carbon dioxide can be activated and subsequently converted into value-added chemicals/fuels. Apart from that, certain issues related to scaling up the technology have been highlighted. The author concludes by putting light on various problems related to the technologies, which need efforts and research so as to achieve practically viable catalysts for CO2 conversion to chemicals and fuel.

Mitigating Global Warming Through Carbonic Anhydrase-Mediated Carbon Sequestration

Chapter

May 2021

Industrial Revolution has led to an unprecedented rise in carbon dioxide concentrations in the atmosphere. Among various methods available for carbon capture from the industrial emissions such as flue gas, carbonic anhydrase (CA)-based carbon capture techniques have been evolved and gained immense attention in the recent years. Carbonic anhydrase (CA) is a zinc metalloenzyme, which is an essential biocatalyst for all living beings. It plays a role in accelerating the hydration and dehydration of carbon dioxide. This enzyme can be utilized in vitro for capturing carbon from industrial emissions. Thermo-alkali stable CAs from prokaryotes are the most promising candidates for biomimetic carbon sequestration owing to the high temperature of flue gas and alkaline condition needed for precipitation of calcium carbonate formed in the reaction. These CAs can be essentially immobilized on various solid supports and matrices for developing bioreactors and their continuous operation. This chapter reviews developments in utilizing CAs of prokaryotes in carbon capture technologies.

Soil Respiration under 90 Year-Old Rye Monoculture and Crop Rotation in the Climate Conditions of Central Poland

Article

Full-text available

Dec 2020

This study, aimed at assessing the rate of soil respiration under different crop rotation and fertilization conditions, was carried out on long-term (since 1923) experimental plots with rye monoculture and 5-crop rotation in Skierniewice (Central Poland). The treatments included mineral-organic (CaNPK+M) and organic (Ca+M) fertilization (where M is farmyard manure). Soil respiration was measured in situ by means of infrared spectroscopy using a portable FTIR spectrometer Alpha. CO2 fluxes from CaNPK+M-treated soils under cereals cultivated in monoculture and crop rotations were not statically different. Respiration of soil under lupine cultivated in crop rotation was higher than under cereals. N-fertilization and its succeeding effect increased soil respiration, and significantly altered its distribution over the growing season. Our results indicate that in the climatic conditions of Central Europe, respiration of sandy soils is more dependent on the crop species and fertilization than on the crop rotation system. Omission of mineral fertilization significantly decreases soil respiration. The CO2 fluxes were positively correlated with soil temperature, air temperature, and soil content of NO3− and NH4+.

Effect of animal manure, crop type, climate zone, and soil attributes on greenhouse gas emissions from agricultural soils-A global meta-analysis

Article

Sep 2020
J CLEAN PROD

Agricultural lands, because of their large area and exhaustive management practices, have a substantial impact on the earth’s carbon and nitrogen cycles, and agricultural activities consequence in discharges of greenhouse gases (GHGs). Globally, greenhouse gases (GHGs) emissions especially carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) from the agricultural sector are increasing due to anthropogenic activities. Although, the application of animal manure to the agricultural soil as an organic fertilizer not only improves soil health and agricultural production but also has a significant impact on GHGs emissions. But the extent of GHGs emissions in response to manure application under diverse environmental conditions is still uncertain. Here, a meta-analysis study was conducted using field data (48 peer-reviewed publications) published from 1989 to 2019. Meta-analysis results showed that poultry manure considerably increased CO2, CH4, and N2O emissions than pig and cattle manure. Furthermore, application of poultry manure also increased (lnRR =0.141, 95% CI =0.526-0.356) GWP (global warming potential) of total soil GHGs emissions. While, the significant effects on CO2, CH4, and N2O emissions also occurred at manure rate > 320 kg N ha-1 and > 60% water filled pore space. The maximum concentrations of CO2, CH4, and N2O emissions were observed in neutral soils (lnRR =3.375, 95% CI =3.323-3.428), alkaline soils (lnRR =1.468, 95% CI =1.403-1.532), and acidic soils (lnRR =2.355, 95% CI =2.390-2.400), respectively. Soil texture, climate zone and crop type were also found significant factors to increase GHGs emissions. Thus, this meta analysis revealed a knowledge gap concerning the consequences of animal manure application and rate, climate zone, and physicochemical properties of soil on GHGs emissions from agricultural soils.

Simulating the effects of soil temperature and soil moisture on CO2 and CH4 emissions in rice straw-enriched paddy soil

Article

Nov 2020
CATENA

Paddy soil from a site in northeast China was incubated with ¹³C-labeled rice straw in a laboratory study, and the effects of soil temperature and moisture on CO2 and CH4 emissions were measured using stable isotope ratio mass spectrometry. Aerobic incubation experiments were conducted at three soil temperatures (−10 °C, 0 °C, and 10 °C) and two soil moistures (60% and 100% water-filled pore space (WFPS)) in a laboratory for 24 weeks to simulate the rice-fallow season. An anaerobic incubation experiment was carried out for 16 weeks under a soil temperature of 25 °C and a 1 cm submerged layer to simulate the rice-growing season. Our results showed that increases in both soil temperature and soil moisture significantly promoted the cumulative CO2 emissions from rice straw during aerobic incubation. Furthermore, during anaerobic incubation, the cumulative emissions of CO2 and CH4 from rice straw decreased with increasing aerobic incubation soil temperature and soil moisture. The CO2 and CH4 emission ratios from rice straw throughout the incubation duration ranged from 6.6–15.7% and 0.0–3.0%, respectively. The addition of rice straw promoted a priming effect on native soil organic carbon (SOC) mineralization and produced CO2 emissions, which positively impacted priming during the aerobic (rice-fallow season) and anaerobic incubation (rice-growing season). The positive priming effect of rice straw on the CO2 emission duration ranged from 75.0% to 274.3% by the end of the 40-week incubation period. Furthermore, the aforementioned effect first increased and then decreased as the aerobic incubation soil temperature increased, with the greatest effect at 0 °C and lowest at 10 °C. These results suggest that high temperature during the rice-fallow season promotes the decomposition of rice straw C and leads to a decreased positive priming effect on native SOC during the rice-fallow and rice-growing seasons under the seasonal conditions of northeast China, and that it also leads to decreased CH4 production during the rice-growing season. These results have scientific significance for rational utilization of rice straw and mitigation of greenhouse effect in northeast China.

Soils as Driver and Victim of Climate Change in Egypt

Chapter

Apr 2020

Reda Ragab Shahin

Egypt is a country that foresees to face severe effects owing to climate change. Soil may consider an important source of greenhouse gas emissions (i.e. carbon dioxide, methane and nitrous oxides). The drivers of soil GHG emissions are soil type and composition (i.e. soil texture, pH, soil organic matter (SOM), etc.), soil temperature, moisture, fertilization, soil miss-management (Tillage), rice cultivation and burning of Crop residues. Soil also considered as a victim of climate change. Global warming may induce, depletion of soil organic matter that causes the decline of soil fertility, poor soil water regime, shifting of soil microbiome and soil compaction (i.e. Increase soil compaction, surface sealing and crust formation). Global warming induces also sea level rise (SLR) on soils of Egypt which increase the area of submerged lands in northern Nile Delta and consequently soil salinization. With climate change, more frequent extreme precipitation and drought events are projected which may exacerbate the rate and soil susceptibility to accelerated erosion, salinization and other degradation processes, leading to further carbon losses. In conclusion, this chapter summarizes geographical nature of climate change impacts and the history of flooding rainstorms in Egypt.

Effects of fertilization and straw return methods on the soil carbon pool and CO2 emission in a reclaimed mine spoil in Shanxi Province, China

Article

Dec 2019
SOIL TILL RES

Reclaimed soil is similar to an “empty cup” with a large carbon (C) sequestration potential. Agricultural management practices strongly influence C storage and soil carbon dioxide (CO2) emission. The objective of this study was to identify the effects of fertilization and straw return methods on the soil C pool and CO2 emission in a reclaimed mine spoil. Thus, we studied the effects of four fertilization treatments [chemical fertilizer (NP), manure (M), 50% M plus 50% NP (NPM), and unfertilized control (CK)] and three straw return methods [no straw return (no straw), return of straw mixed with soil (straw mixing), and return of straw to the surface of the soil (straw mulching)] in a mine reclamation region by examining changes in the soil C pool and CO2 emission. The soil C pool was evaluated by acid hydrolysis, considering three pools: (a) labile pool I (LP I), obtained by hydrolysis with 5 N H2SO4 at 105 °C for 30 min; (b) labile pool II (LP II), obtained by hydrolysis with 26 N H2SO4 at room temperature overnight, followed by 2 N H2SO4 at 105 °C for 3 h; and (c) the recalcitrant pool, measured as the unhydrolyzed residue. The CO2 emission/C sequestration and CO2 emission/grain yield ratios were used as indicators of C emission. Compared with the CK, the NPM treatment was the most efficient among the fertilization treatments in increasing grain yield (136%) and C sequestration (311%) and reducing the CO2 emission/C sequestration (62%) and CO2 emission/grain yield (32%) ratios. The straw mixing treatment had more soil organic carbon (SOC), a larger LP I and LP II, and more C sequestration than the other straw return treatments. The addition of manure resulted in a higher distribution rate of new organic C to the labile C pool (73–78%) than the addition of inorganic fertilizer (45%). Soil C emissions were mainly concentrated in the maize growing season, accounting for more than 80% of the total annual C emissions. LP I, LP II and CO2 emission were significantly positive correlated with SOC and yield. Therefore, soil C pools and CO2 emissions are significantly influenced by fertilization regimes and straw return methods, which should be used to important indicators to estimate the C balance in agro-ecosystems during the process of mine spoil reclamation.

Effects of Temperature and Moisture on Soil Organic Carbon Mineralization

Article

Full-text available

Aug 2019

As an important index of soil fertility and ecological balance, soil organic carbon had been universal concern. This paper summarized research conditions of temperature and moisture on soil organic carbon in recent years, introduces the effects of temperature, freezing-thawing cycles, water and dry-wet cycles on soil organic carbon mineralization, and discusses the dynamics research of soil organic carbon mineralization, proposed to be further resolved problems.

Spatial and temporal variability in agricultural fields

Article

Full-text available

May 1991
CAN J SOIL SCI

Chamber measurements of CO2 evolution were made on bare soil, and in maize (1988) and wheat (1989) crops in order to study the spatial and temporal variability of soil respiration (Rsoil). Semivariograms showed no definite structure of spatial auto-correlation on bare soil when measurements were made along transects. Spatial variability was shown to occur at a scale smaller than 15 cm. In a maize crop, Rsoil in the row was significantly higher than in the interrow when the soil surface was dry due to the contribution of plant roots. Under wet soil conditions, Rsoil in the interrow compacted by the tractor wheel was lower than on noncompacted soil and no significant difference was found between rows and interrows. This was due to the role of microbial activity which was dominant except in the compacted interrow where lower airfilled porosity caused lower Rsoil. The maximum Rsoil during the growing season coincided with the period of maximum growth of both crops. A post-rainfall Rsoil burst is also described. -from Authors

Pulse emissions of N2O and CO2 from an arable field depending on fertilization and tillage practice

Article

Full-text available

Nov 2011
AGR ECOSYST ENVIRON

Nitrous oxide (N2O) emissions from soil are characterized by strong emission pulses. Although several mechanisms are known to create them, pulses are difficult to predict. Currently there is no established systematic way to identify pulses from long-term static chamber measurement results. In this study we suggest a simple algorithm for pulse identification. The algorithm was applied on time series of N2O and carbon dioxide (CO2) fluxes from a field study on the long-term impact of fertilization and tillage practice. Between 4 and 9% of N2O values were pulse values; 20–60% of total emission was emitted as pulses. Minimum tillage resulted in more pulses than plowing. In contrast, long-term averages of N2O losses from nitrogen (N) fertilizer were similar (3–4%) for all management practices. N2O emissions per crop yield for increased fertilization practice were double the values for reduced fertilization practice independent of tillage practice. CO2 emission pulses were scarce and there was no significant effect of management practice on CO2 pulse probability.

Grazing increases the temperature sensitivity of soil organic matter decomposition in a temperate grassland

Article

Full-text available

Mar 2012
ENVIRON RES LETT

We tested the effects of ungulate grazing and nutrient availability on the temperature sensitivity of soil respiration (CO2) and methane (CH4) emissions in semi-natural temperate grassland. To do this, soil taken from long term grazed and ungrazed grassland was incubated at four temperatures (4, 10, 15 and 20 °C) with two levels of nutrient (NP) addition. The results showed that the variation in soil CO2 and CH4 emissions was explained by temperature and grazing, with grazing increasing the temperature sensitivity of CO2 and CH4 production by between 15 and 20 °C. This response was constrained by nutrient availability for CO2, but not CH4. These findings suggest that grazing could potentially have important impacts on the temperature sensitivity of greenhouse gas emissions in nutrient limited grasslands.

Soil Respiration under Maize Crops: Effects of Water, Temperature, and Nitrogen Fertilization

Article

Full-text available

May 2007
SOIL SCI SOC AM J

To evaluate the response of soil respiration to soil moisture, temperature, and N fertilization, and estimate the contribution of soil and rhizosphere respiration to total soil CO2 emissions, a field experiment was conducted in the Fengqiu State Key Agro-Ecological Experimental Station, Henan, China. The experiment included four treatments: bare soil fertilized with 150 kg N ha(-1) (CK), and maize (Zea mays L.)-cropped soils amended with 0 (NO), 150 (N150), and 250 (N250) kg N ha-1. Mean seasonal soil CO2 emissions in the CK, NO, N150, and N250 treatments were estimated to be 294, 598, 541, and 539 g C m(-2), respectively. The seasonal soil CO2 fluxes were significantly affected by soil temperature, with the change in the rate of flux for each 10 degrees C increase in temperature (Q(10)) of 1.90 to 2.88, but not by soil moisture. Nitrogen fertilization resulted in a 10.5% reduction in soil CO 2 flux; however, it did not significantly increase the maize aboveground biomass but did increase maize yield. Soil respiration measurement using the root-exclusion technique indicated that soils fertilized with 150 kg N ha(-1) contributed 54% of the total soil CO 2 emission, or 8% of soil organic C down to a depth of 40 cm. An amount of C equivalent to 26% of the net assimilated C in harvested above- and belowground plant biomass was returned to the atmosphere by rhizosphere respiration.

Sources of CO2 emission from a northern peatland: Root respiration, exudation, and decomposition

Article

Full-text available

Jul 2005
ECOLOGY

Northern peatlands are Substantial sinks of carbon (C), yet the sources of carbon dioxide (CO2) emitted from peatlands are largely unknown. Since the relationship between roots and peat in C cycling is important, vascular plants growing on the surface of peat deposits should influence CO2 efflux from the peat surface and the overall C balance in peatlands. In our study, 30-cm peat cores were removed from an ombrotrophic bog in boreal, continental western Canada. Surface vegetation in the cores remained intact and included a continuous bryophyte cover dominated by Sphagnum fuscum. In addition, some cores were collected such that either ericaceous shrubs (Ledum groenlandicum) or sedges (Eriophorum vaginatum) were present. We investigated how the presence of each vegetation type influenced soil respiration and the microbial mineralization of root exudates using a pulse C-14 labeling of vegetation in the intact peat cores. The role of root biomass and toot respiration in CO2 emission and C allocation was quantified for each type of vegetation and compared through both measurement and modeling. Our results show that vascular plants contributed 35-57% of total CO2 efflux from the peat surface, primarily derived from rhizosphere processes, including root respiration as well as microbial mineralization of root exudates. The mineralization of root exudates contributed 14-53 mu mol C-CO(2)(.)m(-2).d(-1) (17-24% of total) to CO2 efflux, depending on vegetation type and moisture conditions. The type of vegetation present did not influence the total amount of photosynthetic fixation over the course of the study, but did affect how C was allocated within and between both the aboveground and belowground components of the peat column.

Microbial use of organic amendments in saline soils monitored by changes in the 13C/12C ratio

Article

Full-text available

May 2008
SOIL BIOL BIOCHEM

An incubation experiment was carried out to investigate whether salinity at high pH has negative effects on microbial substrate use, i.e. the mineralization of the amendment to CO2 and inorganic N and the incorporation of amendment C into microbial biomass C. In order to exploit natural differences in the 13C/12C ratio, substrate from two C4 plants, i.e. highly decomposed and N-rich sugarcane filter cake and less decomposed N-poor maize leaf straw, were added to two alkaline Pakistani soils differing in salinity, which had previously been cultivated with C3 plants. In soil 1, the additional CO2 evolution was equivalent to 65% of the added amount in the maize straw treatment and to 35% in the filter cake treatment. In the more saline soil 2, the respective figures were 56% and 32%. The maize straw amendment led to an identical immobilization of approximately 48μgNg−1 soil over the 56-day incubation in both soils compared with the control soils. In the filter cake treatment, the amount of inorganic N immobilized was 8.5μgNg−1 higher in soil 1 than in soil 2 compared with the control soils. In the control treatment, the content of microbial biomass C3-C in soil 1 was twice that in soil 2 throughout the incubation. This fraction declined by about 30% during the incubation in both soils. The two amendments replaced initially similar absolute amounts of the autochthonous microbial biomass C, i.e. 50% of the original microbial biomass C in soil 1 and almost 90% in soil 2. The highest contents of microbial biomass C4-C were equivalent to 7% (filter cake) and 11% (maize straw) of the added C. In soil 2, the corresponding values were 14% lower. Increasing salinity had no direct negative effects on microbial substrate use in the present two soils. Consequently, the differences in soil microbial biomass contents are most likely caused indirectly by salinity-induced reduction in plant growth rather than directly by negative effects of salinity on soil microorganisms.

The effect of different tillage and residue management practices on soil characteristics, inorganic N dynamics and emissions of N2O, CO 2 and CH4 in the central highlands of Mexico: A laboratory study

Article

Full-text available

Jan 2009

Conservation agriculture in its version of permanent raised bed planting with crop residue retention increases yields and improves soil characteristics, e.g. aggregate distribution, organic matter content, so it remained to be seen how greenhouse gas emissions and dynamics of C and N might be altered. The objective of this study was to investigate how conservation agriculture with permanent raised beds, tied ridges, i.e. dykes within the furrows to prevent water run-off, and residue retention affected greenhouse gas emissions. A field experiment was started in 1999 comparing permanent and conventionally tilled raised beds with different residue management under rain fed conditions. Soil was characterized and emissions of CH4, N2O and CO2 and dynamics of NH4 +, NO2 − and NO3 − were monitored in a laboratory experiment. The crop and tied ridges had no effect on soil characteristics and dynamics of C and N. Tilled beds reduced the water holding capacity (WHC) 1.1 times and increased conductivity 1.3 times compared to soil under nontilled beds with retention of all crop residues. The WHC, organic C, soil microbial biomass and total N were ≥1.1 larger in soil from nontilled beds where the crop residue was retained compared to where it was removed after only 6 years. The emission of CO2 was 1.2 times and production of NO3 − 1.8 times larger in nontilled beds where the crop residue was retained compared to where it was removed. The CO2 emission was 1.2 times and the emission of N2O after 1 day 2.3 times larger in soil under tilled beds compared to nontilled beds with full residue retention, while the increase in concentration of NO3 − was 0.05 mg N kg−1 soil in the former and 2.38 in the latter. We found that permanent raised bed planting with crop residue retention decreased emissions of N2O and CO2 compared to soil under conventionally tilled raised beds. Production of NO3 − is larger in soil with permanent raised bed planting with crop residue retention compared to conventionally tilled raised beds.

Rhizosphere Effects on Decomposition: Controls of Plant Species, Phenology, and Fertilization

Article

Full-text available

Sep 2003

Plant species and soil fertility presumably control rhizosphere effects on soil organic matter (SOM) decomposition, but qualitative and quantitative descriptions of such controls are still sparse. In this study, rhizosphere effects of soybean [Glycine max (L.) Merr.] and spring wheat (Triticum aestivum L.) on SOM decomposition were investigated at four phenological stages under three levels of fertilization in a greenhouse experiment using natural 13C tracers. The magnitude of the rhizosphere effect ranged from 0% to as high as 383% above the decomposition rate in the no-plant control, indicating that the rhizosphere priming can substantially intensify decomposition. The rhizosphere priming effect was responsible for a major portion of the total soil C efflux. Cumulative soil C loss caused by rhizosphere effects during the whole growing season equated to the amount of root biomass C for the soybean treatment, and 71% of root biomass C for the wheat treatment. Different plant species produced significantly different rhizosphere priming effects. The overall rhizosphere priming effect of soybean plants was significantly higher than for wheat plants. Plant phenology significantly influenced the rhizosphere priming effect. Little rhizosphere effect occurred in both wheat and soybean treatments initially. The priming effect of the wheat rhizosphere reached 287% above the no-plant control at the flowering stage and declined significantly afterward. The priming effect of the soybean rhizosphere peaked at 383% above the no-plant control during the late vegetative stage and remained at high levels onward. Contrary to many published reports, NPK fertilization did not significantly modify the rhizosphere priming effect.

An appropriate time-window for measuring soil CO2 efflux: A case study on a Black soil in north-east China

Article

Full-text available

Jul 2012
ACTA AGR SCAND B-S P

Soil CO2 efflux rate is influenced by soil temperature which varies with time within a day. In order to determine a measuring time-window which can represent the daily average soil CO2 efflux rate from a Black soil in north-east China, soil CO2 efflux rates from no-tillage (NT) and mouldboard plough tillage (MP) plots were measured at a 2-h interval over 48 h four times in the growing season of 2008. Results showed that during the course of measurements, NT soil had a higher soil CO2 efflux rate than MP soil. Daily average soil CO2 efflux rate was matched relatively well with the CO2 efflux rate occurring between 09:00 h and 13:00 h, and between 19:00 h and 23:00 h. Our results indicate that the soil CO2 efflux rate measured between 09:00 and 11:00 h represents the daily average soil CO2 efflux rate during sunny days. When the measurements were conducted outside this time window, a procedure to adjust the CO2 efflux rates measured between 07:00 and 21:00 h (outside of the optimum time-window) to estimate daily average soil CO2 efflux rate is described.

Management options for reducing CO2 emissions from agricultural soils

Article

Full-text available

Jan 2000

Crop-based agriculture occupies 1.7 billion hectares, globally, with a soil C stock of about 170 Pg. Of the past anthropogenic CO2 additions to the atmosphere, about 50 Pg C came from the loss of soil organic matter (SOM) in cultivated soils. Improved management practices, however, can rebuild C stocks in agricultural soils and help mitigate CO2 emissions. Increasing soil C stocks requires increasing C inputs and/or reducing soil heterotrophic respiration. Management options that contribute to reduced soil respiration include reduced tillage practices (especially no-till) and increased cropping intensity. Physical disturbance associated with intensive soil tillage increases the turnover of soil aggregates and accelerates the decomposition of aggregate-associated SOM. No-till increases aggregate stability and promotes the formation of recalcitrant SOM fractions within stabilized micro- and macroaggregate structures. Experiments using13 C natural abundance show up to a two-fold increase in mean residence time of SOM under no-till vs intensive tillage. Greater cropping intensity, i.e., by reducing the frequency of bare fallow in crop rotations and increasing the use of perennial vegetation, can increase water and nutrient use efficiency by plants, thereby increasing C inputs to soil and reducing organic matter decomposition rates. Management and policies to sequester C in soils need to consider that: soils have a finite capacity to store C, gains in soil C can be reversed if proper management is not maintained, and fossil fuel inputs for different management practices need to be factored into a total agricultural CO2 balance.

Effects of soil water content on soil respiration in forests and cattle pastures of eastern Amazonia

Article

Full-text available

Jan 2000

The effect of soil water content on efflux of CO2 from soils has been described by linear, logarithmic, quadratic, and parabolic functions of soil water expressed as matric potential, gravimetric and volumetric water content, water holding capacity, water-filled pore space, precipitation indices, and depth to water table. The effects of temperature and water content are often statistically confounded. The objectives of this study are: (1) to analyze seasonal variation in soil water content and soil respiration in the eastern Amazon Basin where seasonal temperature variation is minor; and (2) to examine differences in soil CO2 emissions among primary forests, secondary forests, active cattle pastures, and degraded cattle pastures. Rates of soil respiration decreased from wet to dry seasons in all land uses. Grasses in the active cattle pasture were productive in the wet season and senescent in the dry season, resulting in the largest seasonal amplitude of CO2 emissions, whereas deep-rooted forests maintained substantial soil respiration during the dry season. Annual emissions were 2.0, 1.8, 1.5, and 1.0 kg C m-2 yr-1 for primary forest, secondary forest, active pasture, and degraded pasture, respectively. Emissions of CO2 were correlated with the logarithm of matric potential and with the cube of volumetric water content, which are mechanistically appropriate functions for relating soil respiration at below-optimal water contents. The parameterization of these empirical functions was not consistent with those for a temperate forest. Relating rates of soil respiration to water and temperature measurements made at some arbitrarily chosen depth of the surface horizons is simplistic. Further progress in defining temperature and moisture functions may require measurements of temperature, water content and CO2 production for each soil horizon.

Crop residues and fertilizer nitrogen influence residue decomposition and nitrous oxide emission from a Vertisol

Article

Full-text available

Jan 2011

Crop residues with high C/N ratio immobilize N released during decomposition in soil, thus reducing N losses through leaching, denitrification, and nitrous oxide (N2O) emission. A laboratory incubation experiment was conducted for 84days under controlled conditions (24°C and moisture content 55% of water-holding capacity) to study the influence of sugarcane, maize, sorghum, cotton and lucerne residues, and mineral N addition, on N mineralization–immobilization and N2O emission. Residues were added at the rate of 3t C ha−1 to soil with, and without, 150kg urea Nha−1. The addition of sugarcane, maize, and sorghum residues without N fertilizer resulted in a significant immobilization of soil N. Amended soil had significantly (P < 0.05) lower NO3−–N, which reached minimum values of 2.8mgN kg−1 for sugarcane (at day28), 10.3mgN kg−1 for maize (day7), and 5.9mgN kg−1 for sorghum (day7), compared to 22.7mgN kg−1 for the unamended soil (day7). During 84days of incubation, the total mineral N in the residues + N treatments were decreased by 45mgN kg−1 in sugarcane, 34mgkg−1 in maize, 29mgkg−1 in sorghum, and 16mgkg−1 in cotton amended soil compared to soil + N fertilizer, although soil NO3−–N increased by 7mgkg−1 in lucerne amended soil. The addition of residues also significantly increased amended soil microbial biomass C and N. Maximum emissions of N2O from crop residue amended soils occurred in the first 4–5days of incubation. Overall, after 84days of incubation, the cumulative N2O emission was 25% lower with cotton + N fertilizer, compared to soil + N fertilizer. The cumulative N2O emission was significantly and positively correlated with NO3−–N (r = 0.92, P < 0.01) and total mineral N (r = 0.93, P < 0.01) after 84days of incubation, and had a weak but significant positive correlation with cumulative CO2 in the first 3 and 5days of incubation (r = 0.59, P < 0.05). KeywordsCrop residues–Fertilizer N–Mineral N–Nitrous oxide–Vertisol

Stabilization Mechanisms of Soil Organic Matter: Implications for C-Saturation of Soils

Article

Full-text available

Apr 2002

The relationship between soil structure and the ability of soil to stabilize soil organic matter (SOM) is a key element in soil C dynamics that has either been overlooked or treated in a cursory fashion when developing SOM models. The purpose of this paper is to review current knowledge of SOM dynamics within the framework of a newly proposed soil C saturation concept. Initially, we distinguish SOM that is protected against decomposition by various mechanisms from that which is not protected from decomposition. Methods of quantification and characteristics of three SOM pools defined as protected are discussed. Soil organic matter can be: (1) physically stabilized, or protected from decomposition, through microaggregation, or (2) intimate association with silt and clay particles, and (3) can be biochemically stabilized through the formation of recalcitrant SOM compounds. In addition to behavior of each SOM pool, we discuss implications of changes in land management on processes by which SOM compounds undergo protection and release. The characteristics and responses to changes in land use or land management are described for the light fraction (LF) and particulate organic matter (POM). We defined the LF and POM not occluded within microaggregates (53–250 m sized aggregates as unprotected. Our conclusions are illustrated in a new conceptual SOM model that differs from most SOM models in that the model state variables are measurable SOM pools. We suggest that physicochemical characteristics inherent to soils define the maximum protective capacity of these pools, which limits increases in SOM (i.e. C sequestration) with increased organic residue inputs.

Effects of organic and mineral fertilizer nitrogen on greenhouse gas emissions and plant-captured carbon under maize cropping in Zimbabwe

Article

Full-text available

Jun 2011

Optimizing a three-way pact comprising crop yields, fertility inputs and greenhouse gases may minimize the contribution of croplands to global warming. Fluxes of N2O, CO2 and CH4 from soil were measured under maize (Zea mays L.) grown using 0, 60 and 120kgN hm-2 as NH4NO3-N and composted manure-N in three seasons on clay (Chromic luvisol) and sandy loam (Haplic lixisol) soils in Zimbabwe. The fluxes were measured using the static chamber methodology involving gas chromatography for ample air analysis. Over an average of 122days we estimated emissions of 0.1 to 0.5kg N2O-N hm−2, 711 to 1574kg CO2-C hm−2 and−2.6 to 5.8kg CH4-C hm−2 from six treatments during season II with the highest fluxes. The posed hypothesis that composted manure-N may be better placed as a mitigation option against soil emissions of GHG than mineral fertilizer-N was largely supported by N2O fluxes during the wet period of the year, but with high level of uncertainty. Nitrogen addition might have stimulated both emissions and consumption of CH4 but the sink or source strength depended highly on soil water content. We concluded that the application of mineral-N and manure input may play an important role with reference to global warming provided the season can support substantial crop productivity that may reduce the amount of N2O loss per unit yield. Confidence in fluxes response to agricultural management is still low due to sporadic measurements and limited observations from the southern African region. KeywordsCattle manure–Greenhouse gas–Maize–Mineral fertilizer–Plant captured carbon

Soil Respiration and Global Carbon Cycle

Article

Full-text available

Jan 2000

Soil respiration is the primary path by which CO2fixed by land plants returns to the atmosphere. Estimated at approximately 75 Ã 1015gC/yr, this large natural flux is likely to increase due changes in the Earth's condition. The objective of this paper is to provide a brief scientific review for policymakers who are concerned that changes in soil respiration may contribute to the rise in CO2in Earth's atmosphere. Rising concentrations of CO2in the atmosphere will increase the flux of CO2from soils, while simultaneously leaving a greater store of carbon in the soil. Traditional tillage cultivation and rising temperature increase the flux of CO2from soils without increasing the stock of soil organic matter. Increasing deposition of nitrogen from the atmosphere may lead to the sequestration of carbon in vegetation and soils. The response of the land biosphere to simultaneous changes in all of these factors is unknown, but a large increase in the soil carbon pool seems unlikely to moderate the rise in atmo

Tillage and Crop Residue Effects on Soil Carbon and Carbon Dioxide Emission in Corn–Soybean Rotations

Article

Full-text available

Mar 2005

Soil C change and CO2 emission due to different tillage systems need to be evaluated to encourage the adoption of conservation practices to sustain soil productivity and protect the environment. We hypothesize that soil C storage and CO2 emission respond to conservation tillage differently from conventional tillage because of their differential effects on soil properties. This study was conducted from 1998 through 2001 to evaluate tillage effects on soil C storage and CO2 emission in Clarion-Nicollet-Webster soil association in a corn [Zea mays L.]-soybean [Glycine max (L.) Merr.] rotation in Iowa. Treatments included no-tillage with and without residue, strip-tillage, deep rip, chisel plow, and moldboard plow. No-tillage with residue and strip-tillage significantly increased total soil organic C (TC) and mineral fraction C (MFC) at the 0- to 5- and 5- to 10-cm soil depths compared with chisel plow after 3 yr of tillage practices. Soil CO2 emission was lower for less intensive tillage treatments compared with moldboard plow, with the greatest differences occurring immediately after tillage operations. Cumulative soil CO2 emission was 19 to 41% lower for less intensive tillage treatments than moldboard plow, and it was 24% less for no-tillage with residue than without residue during the 480-h measurement period. Estimated soil mineralizable C pool was reduced by 22 to 66% with less intensive tillage treatments compared with moldboard plow. Adopting less intensive tillage systems such as no-tillage, strip-tillage, deep rip, and chisel plow and better crop residue cover are effective in reducing CO2 emission and thus improving soil C sequestration in a corn-soybean rotation.

Rhizosphere Effects on Decomposition

Article

Sep 2003
SOIL SCI SOC AM J

Plant species and soil fertility presumably control rhizosphere effects on soil organic matter (SOM) decomposition, but qualitative and quantitative descriptions of such controls are still sparse. In this study, rhizosphere effects of soybean [Glycine max (L.) Merr.] and spring wheat (Triticum aestivum L.) on SOM decomposition were investigated at four phenological stages under three levels of fertilization in a greenhouse experiment using natural 13 C tracers. The magnitude of the rhizosphere effect ranged from 0% to as high as 383% above the decomposition rate in the no-plant control, indicating that the rhizosphere priming can substantially intensify decomposition. The rhizosphere priming effect was responsible for a major portion of the total soil C efflux. Cumulative soil C loss caused by rhizosphere effects during the whole growing season equated to the amount of root biomass C for the soybean treatment, and 71% of root biomass C for the wheat treatment. Different plant species produced significantly different rhizosphere priming effects. The overall rhizosphere priming effect of soybean plants was significantly higher than for wheat plants. Plant phenology significantly influenced the rhizosphere priming effect. Little rhizosphere effect occurred in both wheat and soybean treatments initially. The priming effect of the wheat rhizosphere reached 287% above the no-plant control at the flowering stage and declined significantly afterward. The priming effect of the soybean rhizosphere peaked at 383% above the no-plant control during the late vegetative stage and remained at high levels onward. Contrary to many published reports, NPK fertilization did not significantly modify the rhizosphere priming effect.

Dynamics of soil microbial biomass C, soluble organic C and CO2 evolution after three years of manure application

Article

May 1998
CAN J SOIL SCI

Application of manure and fertilizer affects the rate and extent of mineralization and sequestration of C in soil. The objective of this study was to determine the effects of 3 yr of application of N fertilizer and different manure amendments on CO2 evolution and the dynamics of soil microbial biomass and soluble C in the field. Soil respiration, soluble organic C and microbial biomass C were measured at intervals over the growing season in maize soils amended with stockpiled or rotted manure, N fertilizer (200 kg N ha-1) and with no amendments (control). Manure amendments increased soil respiration and levels of soluble organic C and microbial biomass C by a factor of 2 to 3 compared with the control, whereas the N fertilizer had little effect on any parameter. Soil temperature explained most of the variations in CO2 flux (78 to 95%) in each treatment, but data from all treatments could not be fitted to a unique relationship. Increases in CO2 emission and soluble C resulting from manure amendments were strongly correlated (r2 = 0.75) with soil temperature. This observation confirms that soluble C is an active C pool affected by biological activity. The positive correlation between soluble organic C and soil temperature also suggests that production of soluble C increases more than mineralization of soluble C as temperature increases. The total manure-derived CO2-C was equivalent to 52% of the applied stockpiled-manure C and 67% of the applied rotted-manure C. Estimates of average turnover rates of microbial biomass ranged between 0.72 and 1.22 yr-1 and were lowest in manured soils. Manured soils also had large quantities of soluble C with a slower turnover rate than that in either fertilized or unamended soils.

Residue Type and Placement Effects on Decomposition: Field Study and Model Evaluation

Article

Jan 1993
T ASABE

Decomposition of corn(Zea mays L.), soybean (Glycine max (L.) Merr.), wheat (Triticum aestivum L.), grain sorghum (Sorghum bicolor (L.) Moench), and cotton (Gossypium hirsutum L.) residues and dead roots was studied under field conditions at the Midwest Claypan Experimental Farm located near Kingdom City, Missouri. Residues infiberglass bags were placed on the soil surface and 0.15 m above and below the surface of a Mexico silt loam (Udollic Ochraqualf). Root bags were also buried 0.15 m below the surface. Samples were collected 11 times during the two-year study. Mass losses in one year for above-surface, surface, buried residue, and dead root were 41, 66, 78, and 65%, respectively, for corn; 37, 66, 79, and 51 %for soybean; 17, 36, 69, and 64%for wheat; 45, 66, 80, and 76%for grain sorghum; and 40, 58, 76, and 46% for cotton. Decomposition was relatively slow during the second year of the study because of the previous loss of easily decomposed compounds. Decomposition data were used to evaluate a theoretically derived residue decay model. Relationships between predicted and measured mass loss were linear with r2 values> 0.93. Keywords. Decomposition, Field study, Model evaluation.

The effect of chemical fertilizer on soil organic carbon renewal and CO2 emission—a pot experiment with maize

Article

Apr 2011

Background and Aims Previous studies have clearly shown substantial increases of soil organic carbon (SOC) in agricultural soils of Yellow River reaches. Those soils did not receive organic fertilizer input, but did receive chemical fertilizer inputs. Thus, to investigate the hypothesis that the observed SOC increases were driven by chemical fertilizer additions, a maize pot experiment was conducted using a Fluvisol that developed under C3 vegetation in the Yellow River reaches. Methods Using the natural 13C abundance method we calculated the SOC renewal ratio (C renewal), and separated total soil organic carbon (TOC) into maize-derived soil organic carbon (SOCmaize) and original soil organic carbon (SOCoriginal). Carbon dioxide fluxes and microbial biomass carbon (MBC) were determined by closed chamber method and fumigation-extraction method, respectively. The experiment included five treatments: (1) NPK: application of chemical fertilizer NPK; (2) NP, application of chemical fertilizer NP; (3) PK: application of chemical fertilizer PK; (4) NK, application of chemical fertilizer NK; and (5) CK: unfertilized control. Results Fertilization increased maize biomass (including grain, straw and root), TOC, C renewal, SOCmaize, maize-derived carbon (MDC: including SOCmaize, and root and stubble biomass carbon) and MBC, and these values among the treatments ranked NPK>NP>PK>NK>CK. The C renewal was 5.54–8.50% across the treatments. Fertilization also increased soil CO2 emission (including root respiration and SOCoriginal decomposition), while the SOCoriginal decomposition during the maize growing season only amounted to 74.0–93.4 and 33.5–46.1% of SOCmaize and MDC among the treatments, respectively. Thus input was larger than export, and led to SOC increase. Maize grain and straw biomass were positively and significantly correlated with soil δ13C, TOC, C renewal, SOCmaize, MDC and MBC. Conclusions The study suggests that chemical fertilizer application could increase C renewal by increasing crop-derived C and accelerating original SOC decomposition, and that as long as a certain level of crop yield or aboveground biomass can be achieved, application of chemical fertilizer alone can maintain or increase SOC level in Fluvisol in the Yellow River reaches.

Soil carbon dioxide flux from shelterbelts in farmland in temperate arid region, northwest China

Article

Feb 2012
EUR J SOIL BIOL

As a managed ecosystem, soil respiration in farmland shelterbelt has seldom been reported. In this study, soil respiration was measured using an automated CO2 efflux system (LI-COR 8100) in 2005 and 2006. Additionally, the effects of abiotic factors on the variation in soil respiration during growing season and the site variation were examined at the Populus and Ulmus pumila farmland shelterbelts in Xinjiang, China. Soil respiration followed the soil temperature in growing season and variation between sampling years at two sites. Soil temperature at 50 cm depth (T50) explained 78.5% of the variation in soil respiration during growing seasons with an exponential equation in Populus site, while soil temperature at 35 cm depth (T35) explaining 64.4% in U. pumila site. There was no apparent relationship between soil respiration and soil water content. The soil respiration was significantly higher in Populus than in U. pumila site, mean soil respiration rate was 3.71 and 1.82 μmol CO2 m−2 s−1, respectively. The greater growth status, the greater quantum yield of photosystemII (ΦPSII) and apparent photosynthetic electron transport rate (ETR) were consistent with the higher soil respiration rate in Populus site. Temperature was a dominant factor driving the temporal variability of soil respiration in growing seasons.

Comparing Measurements Methods of Carbon Dioxide Fluxes in a Soil Sequence Under Land Use and Cover Change in North Eastern Spain

Article

Jan 2012

Long-Term Effects of Organic Amendments on Soil Fertility. A Review

Article

Jan 2010

Common agricultural practices such as excessive use of agro-chemicals, deep tillage and luxury irrigation have degraded soils, polluted water resources and contaminated the atmosphere. There is increasing concern about interrelated environmental problems such as soil degradation, desertification, erosion, and accelerated greenhouse effects and climate change. The decline in organic matter content of many soils is becoming a major process of soil degradation, particularly in European semi-arid Mediterranean regions. Degraded soils are not fertile and thus cannot maintain sustainable production. At the same time, the production of urban and industrial organic waste materials is widespread. Therefore, strategies for recycling such organic waste in agriculture must be developed. Here, we review long-term experiments (3–60 years) on the effects of organic amendments used both for organic matter replenishment and to avoid the application of high levels of chemical fertilizers. The major points of our analysis are: (1) many effects, e.g. carbon sequestration in the soil and possible build-up of toxic elements, evolve slowly, so it is necessary to refer to long-term trials. (2) Repeated application of exogenous organic matter to cropland led to an improvement in soil biological functions. For instance, microbial biomass carbon increased by up to 100% using high-rate compost treatments, and enzymatic activity increased by 30% with sludge addition. (3) Long-lasting application of organic amendments increased organic carbon by up to 90% versus unfertilized soil, and up to 100% versus chemical fertilizer treatments. (4) Regular addition of organic residues, particularly the composted ones, increased soil physical fertility, mainly by improving aggregate stability and decreasing soil bulk density. (5) The best agronomic performance of compost is often obtained with the highest rates and frequency of applications. Furthermore, applying these strategies, there were additional beneficial effects such as the slow release of nitrogen fertilizer. (6) Crop yield increased by up to 250% by long-term applications of high rates of municipal solid waste compost. Stabilized organic amendments do not reduce the crop yield quality, but improve it. (7) Organic amendments play a positive role in climate change mitigation by soil carbon sequestration, the size of which is dependent on their type, the rates and the frequency of application. (8) There is no tangible evidence demonstrating negative impacts of heavy metals applied to soil, particularly when high-quality compost was used for long periods. (9) Repeated application of composted materials enhances soil organic nitrogen content by up to 90%, storing it for mineralization in future cropping seasons, often without inducing nitrate leaching to groundwater.

Measuring and monitoring soil organic carbon stocks in agricultural lands for climate mitigation

Article

Jan 2010

Policies that encourage greenhouse-gas emitters to mitigate emissions through terrestrial carbon (C) offsets -C sequestration in soils or biomass -will promote practices that reduce erosion and build soil fertility, while fostering adaptation to climate change, agricultural development, and rehabilitation of degraded soils. However, none of these benefits will be possible until changes in C stocks can be documented accurately and cost-effectively. This is particularly challenging when dealing with changes in soil organic C (SOC) stocks. Precise methods for measuring C in soil samples are well established, but spatial variability in the factors that determine SOC stocks makes it difficult to document change. Widespread interest in the benefits of SOC sequestration has brought this issue to the fore in the development of US and international climate policy. Here, we review the challenges to documenting changes in SOC stocks, how policy decisions influence offset documentation requirements, and the benefits and drawbacks of different sampling strategies and extrapolation methods.

Carbon Dioxide Emission from Black Soil as Influenced by Land‐Use Change and Long‐Term Fertilization

Article

Apr 2009

Land‐use change and soil management play a vital role in influencing losses of soil carbon (C) by respiration. The aim of this experiment was to examine the impact of natural vegetation restoration and long‐term fertilization on the seasonal pattern of soil respiration and cumulative carbon dioxide (CO2) emission from a black soil of northeast China. Soil respiration rate fluctuated greatly during the growing season in grassland (GL), ranging from 278 to 1030 mg CO2 m−2 h−1 with an average of 606 mg CO2 m−2 h−1. By contrast, soil CO2 emission did not change in bareland (BL) as much as in GL. For cropland (CL), including three treatments [CK (no fertilizer application), nitrogen, phosphorus and potassium application (NPK), and NPK together with organic manure (OM)], soil CO2 emission gradually increased with the growth of maize after seedling with an increasing order of CK < NPM < OM, reaching a maximum on 17 August and declining thereafter. A highly significant exponential correlation was observed between soil temperature and soil CO2 emission for GL during the late growing season (from 3 August to 28 September) with Q10 = 2.46, which accounted for approximately 75% of emission variability. However, no correlation was found between the two parameters for BL and CL. Seasonal CO2 emission from rhizosphere soil changed in line with the overall soil respiration, which averaged 184, 407, and 584 mg CO2 m−2 h−1, with peaks at 614, 1260, and 1770 mg CO2 m−2 h−1 for CK, NPK, and OM, respectively. SOM‐derived CO2 emission of root free‐soil, including basal soil respiration and plant residue–derived microbial decomposition, averaged 132, 132, and 136 mg CO2 m−2 h−1, respectively, showing no difference for the three CL treatments. Cumulative soil CO2 emissions decreased in the order OM > GL > NPK > CK > BL. The cumulative rhizosphere‐derived CO2 emissions during the growing season of maize in cropland accounted for about 67, 74, and 80% of the overall CO2 emissions for CK, NPK, and OM, respectively. Cumulative CO2 emissions were found to significantly correlate with SOC stocks (r = 0.92, n = 5, P < 0.05) as well as with SOC concentration (r = 0.97, n = 5, P < 0.01). We concluded that natural vegetation restoration and long‐term application of organic manure substantially increased C sequestration into soil rather than C losses for the black soil. These results are of great significance to properly manage black soil as a large C pool in northeast China.

Thresholds and interactive effects of soil moisture on the temperature response of soil respiration

Article

Aug 2011
EUR J SOIL BIOL

Ecosystem carbon exchange is poorly understood in low-productivity, semiarid habitats. Here we studied the controls of soil temperature and moisture on soil respiration in climate change field experiment in a sandy forest-steppe. Soil CO2 efflux was measured monthly from April to November in 2003e2008 on plots receiving either rain exclusion or nocturnal warming, or serving as ambient control. Based on this dataset, we developed and compared empirical models of temperature and moisture effects on soil respiration. Results suggest that in this semiarid ecosystem the main controlling factor for soil CO2 efflux is soil temperature, while soil moisture has less, although significant effect on soil respiration. Clear thresholds for moisture effects on temperature sensitivity were identified at 0.6, 4.0 and 7.0 vol% by almost each model, which relate well to other known limits for biological activity in this sandy soil. The relationship between soil respiration and temperature was better described by the Lloyd-Taylor or the Gaussian functions compared to exponential function. Involving additive and interactive soil moisture effects further improved model fitting. Similarly to other low productivity semiarid ecosystems, annual soil carbon efflux values estimated by the different models were rather low (between 123.1 and 139.8 g C m-2 yr-1 as multi-year averages).

Effects of soil mesofauna and farming management on decomposition of clover litter: A microcosm experiment

Article

Apr 2005
SOIL BIOL BIOCHEM

The effects of soil mesofauna and different farming systems on decomposition of clover (Trifolium repens) litter were investigated in a laboratory experiment. Microcosms were incubated for 16 weeks with fine and coarse litterbags in soils from three types of management systems: fallow, integrated farming and organic farming, the latter two cropped with wheat. The effects were studied by analysing litter mass loss, C and N content, DOC, nitrate and pH in soil leachate, and CO2 production, as well as mesofauna. Mesofauna significantly accelerated mass loss and C and N release from clover litter in all three soils. With mesofauna access, at the end of the experiment average clover mass loss was almost twice as high and clover C and N content were 60% lower than without mesofauna. Farming systems influenced the decomposition through affecting both element turnover and mesofauna. Although in the first weeks less N was leached from organic farming than from integrated farming soil, cumulative N leaching did not differ between these soils. However, more than 20% less N was leached from the fallow soil than from the field soils. CO2 production was highest in fallow soil. Here, mesofauna had no effect on this variable. In soil with integrated farming, mesofauna reduced cumulative CO2 production by 10% whereas in soil from organic farming it increased CO2 production by 20%. Our data suggest that differences in C and N turnover in different management systems are strongly mediated by soil mesofauna.

Soil Water Content and Temperature as Independent or Confounded Factors Controlling Soil Respiration in a Temperate Mixed Hardwood Forest

Article

Feb 1998
GLOBAL CHANGE BIOL

Soil CO2 emissions from a cultivated Mollisol: Effects of organic amendments, soil temperature, and moisture

Abstract

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