Residue Management Practices Research Articles

Influence of residual maize crop residue management techniques and fertilizer levels on growth and productivity of zero till maize in rice-maize sequence

A field trial was conducted on a sandy clay loam soil during rabi seasons of 2020-21 and 2021-22 at the Agricultural College Farm, Bapatla to investigate the residual effect of maize crop residue management techniques and fertilizer levels on growth and productivity of zerotill maize in rice-maize sequence. The experiment was laid out in split-split plot design with four maize crop residue management practices (M1 : Exportation of maize stover, M2 : In-situ burning of maize stover (farmers practice), M3 : Mulching maize stover with rotary mulcher and M4 : Incorporation of maize stover with rotovator) as main plot treatments and three fertility levels (100% RDF, 75% RDF and 50% RDF) as sub plot treatments applied to kharif preceded rice and three fertility levels (100% RDF, 75% RDF and 50% RDF) as sub-sub plot levels applied to succeeding maize. Results revealed that incorporation of maize stover with rotovator (M4 ) applied to preceding rice significantly improved plant height (cm), days to 50% tasseling and 50% silking, cob length (cm), cob girth (cm), test weight (g) and grain yield of maize. Mean values for fertiliser levels revealed that plant height (cm), days to 50% tasseling and 50% silking, cob length (cm), cob girth (cm), test weight (g) and grain yield were registered with application of 100% RDF (S1 ) applied to preceding rice and application of 100% RDF applied to succeeding maize. Thus, incorporation of maize stover with rotovator (M4 ) along with application of 100 % RDF applied to preceding rice and application of 100% RDF (S1 ) to succeeding maize is an optimum and sustainable approach to enhance the growth and productivity of zero till maize in rice-maize system.

Impact of Rice Residue Management Practices on Growth and Productivity of Wheat (Triticum aestivum L.)

An experiment was conducted during Rabi season 2020-21 at Instructional Farm of Acharya Narendra Deva Univ. of Agric. & Technology, Narendra Nagar, Kumarganj, Ayodhya (U.P.) to evaluate the effect of different nutrient management practices on growth and yield attributes of wheat. The experiment consisting of 11 treatments, T1 (Control); T2 (chemical fertilizers at 100% RDF); T3 (chemical fertilizers at 75% RDF); T4 (T3 + paddy straw); T5 (T3 + paddy straw + microbial decomposer at 100 ml/plot); T6 (T3 + paddy straw + microbial decomposer at 250 ml/plot); T7 (T3 + paddy straw + microbial decomposer at 500 ml/plot); T8[T3 + (PSB + Mycorrhiza) at 50 ml/plot]; T9[T3+ (PSB + Mycorrhiza) at at 100 ml/plot]; T10[T3 + paddy straw + microbial decomposer at 250 ml/plot + (PSB + Mycorrhiza) at 50 ml/plot]; T11[paddy straw + microbial decomposer at 250 ml/plot + (PSB + Mycorrhiza) at 50 ml/plot) were laid down in triplicate plots in Randomized block design (RBD).Wheat variety PBW-373 was taken as test crop. The results revealed that the application of chemical fertilizersat 75% RDF paddy straw + microbial decomposer at at 250 ml/plot + (PSB + Mycorrhiza) at at 50 ml/plot (T10) recorded significantly higher growth attributes viz. Plant height dry matter accumulations, leaf area index, and yield attributes viz. number of grains per spike, weight of spike, test weight, grain yield, straw yield also biological yield along with harvest index.

Decomposition of harvest residues and soil chemical properties in a Eucalyptus urophylla × grandis plantation under different residue management practices in southern China

Retained residues can return large amounts of nutrients to soil in high-intensity management eucalypt plantations, in which recycling of nutrients is critical for soil quality and forest sustainability. However, the effects of different residue treatments on eucalypt residue decomposition remain unclear. The aim in this study was to determine residue decomposition and nutrient release and soil chemical properties under different treatments of residues in a Eucalyptus urophylla × grandis plantation in southern China. Harvest residues were removed (RR), retained and spread evenly on the soil surface (ER), or retained but stacked into strips on the soil surface (SR). Decomposition of leaves was significantly faster than that of twigs and thick branches and was negatively correlated with initial carbon:nitrogen ratio. The loss of potassium was rapid, whereas losses of carbon, nitrogen, and phosphorus were generally slow. Compared with SR, mass loss and nutrient release accelerated significantly in ER, with shorter half-lives of leaves, twigs, and thick branches. The lowest levels of soil nutrients were in RR, but there were no significant differences between ER and SR. Thus, in this study, residue decomposition was affected by residue type and residue treatment. Decomposition of residues affected soil nutrients by affecting nutrient outflow. In the ER treatment, residues accelerated nutrient cycling and facilitated the accumulation of soil organic carbon, but appropriate fertilization is still needed in E. urophylla × grandis plantations. However, future studies are required to determine whether changes in decomposition rate under different residue management practices lead to long-term changes in soil organic carbon content.

Conservation tillage and residue management improve soil health and crop productivity—Evidence from a rice-maize cropping system in Bangladesh

The rice-maize (R-M) system is rapidly expanding in Bangladesh due to its greater suitability for diverse soil types and environments. The present conventional method of cultivating puddled transplanted rice and maize is input-intensive, decreases soil health through intense ploughing, and ultimately reduces farm profitability. There is a need to investigate alternatives. Accordingly, we conducted a replicated 2-year (2020–2021) field study to investigate the effects of conservation agriculture (CA) based tillage and crop establishment (TCE) techniques and residue management practices on the physical, chemical, and biological properties of soil along with crop productivity and the profitability of rice-maize systems in the sandy loam soil of Northwest Bangladesh. Two TCE techniques Puddled transplanted rice (PTR) followed by Conventional tillage maize (CTM) and strip tillage direct-seeded rice (STDSR) followed by strip-tilled maize (STM) were assigned to the main plots and different percentages of crop residue retention (0, 25, and 50% by height) were allocated to the subplots. Results showed that a reduction in bulk density (BD), soil penetration resistance (SPR), and increased soil porosity were associated with STDSR/STM-based scenarios (strip tillage coupled with 25 and 50% residue retention). The soil organic carbon (SOC) fractions, such as dissolved organic C (DOC), light and heavy particulate organic matter C (POM-C), MAOM, and microbial biomass C (MBC) levels in the 0–10 cm layer under ST based treatments were 95, 8, 6, 2 and 45% greater, respectively, compared to CT with no residue treatment. When compared to the CT treatment, the DOC, light POM-C, heavy POM-C, and MAOM in the 10–20 cm layer with ST treatment were 8, 34, 25, 4 and 37% higher, respectively. Residue retention in ST increased average rice, maize, and system yields by 9.2, 14.0, and 14.12%, respectively, when compared to CT. The system gross margin and benefit-cost ratio (BCR) were $1,515 ha−1 and 1.90 under conventional tillage to $1,696 ha−1 and 2.15 under strip-tillage practices. Thus, our study suggests that CA could be an appropriate practice for sustaining soil fertility and crop yield under R-M systems in light-textured soils or other similar soils in Bangladesh.

Soil quality restoration and yield stabilization in acidic soils of northeastern Himalayas: Five years impact of green manuring and crop residue management

Soil quality restoration and crop productivity maximization are the global challenge to feed the galloping population. The task is much more daunting in a risk-prone, fragile, and low productive hilly region due to the depletion of supporting and regulating ecosystem services. A five-year long-term (2012–2017) field experiment was conducted to stabilize the yield and soil quality through legume green manuring and crop residue recycling in intensified cropping systems in the Eastern Himalayan region of India. Four treatments involving three green manures [green gram (Vigna radiata); cowpea (Vigna unguiculata);Sesbania(Sesbania aculeata) along with control (no-green manure)], three cropping systems [groundnut (Arachis hypogaea)—pea (Pisum sativum); maize (Zea mays)—pea, and maize + groundnut–pea] and two levels of residue management practices [residue removal and residue retention] were evaluated in three times replicated split–split plot design. Among the green manure options,Sesbaniaexerted a significant positive impact on the soil organic carbon (SOC) stock, available micro- (Fe, Mn, Zn, and Cu), and macronutrients (N, P and K) in surface (0–0.15 m) and subsurface (0.15–0.45 m) soils. The improvement in soil enzymatic activities (acid phosphatase, alkaline phosphatase, dehydrogenase, beta-glucosidase, and aryl sulfatase activity) (p< 0.05) inSesbania-treated soil was +28.1% to +38.9% in surface and +18.3% to +27.3% in subsurface soils over non-green manure.Sesbania-treated soils also exhibited higher soil quality index (SQI) and stratification ratio (SR) of available soil nutrients and enzymes over non-green manured soils. Among the cropping systems, groundnut intercropped with maize followed by peas (MGP) within situresidue retention increased (p< 0.05) the available soil macro- and micronutrients, SOC stock, soil enzymes, SR, and SQI in comparison to other cropping systems.Sesbaniagreen manuring and residue retention improved the yield sustainability by +19% and +11% in the MGP system over non-green manuring and residue removal, respectively. Therefore,Sesbaniagreen manuring in the MGP cropping system along with residue retention is recommended for stabilizing the soil quality through enhancing supporting and regulating ecosystem services and maintaining long-term productivity in the fragile Eastern Himalayan ecosystem of India.

Crop Residue Burning and Its Relationship between Health, Agriculture Value Addition, and Regional Finance

Crop residue burning (CRB) poses a serious threat to the climate, soil fertility, human health and wellbeing, and air quality, which increases mortality rates and slumps agricultural productivity. This study conducts a pan-India analysis of CRB burning based on the spatial characteristic of crop residue management practices and analyzes the linkage among health, agriculture value addition, and regional finance using the simultaneous equation to find the causality and panel quantile regression for direct effect and intergroup difference. We discuss some of the alternative crop residue management practices and policy interventions. Along with in situ management, this paper discusses ex situ crop residue management (CRM) solutions. The ex situ effort to manage crop residue failed due to the scarcity of the supply chain ecosystem. Force of habit and time constrain coupled with risk aversion have made farmers reluctant to adopt these solutions. Our results show that financial viability and crop residue have bidirectional causality; therefore, both the central and state governments must provide a financial solution to lure farmers into adopting residue management practices. Our analysis shows that framers are likely to adopt the management solution (farmers have some economic benefits) and are reluctant to adopt the scientific solution because the scientific solution, such as “pusa decomposer”, is constrained by the weather, temperature, and humidity, and these parameters vary throughout India.

Growth Dynamics and Yield of Zero-Till Maize as Influenced by Microbial Consortia Treated Paddy Residue Incorporation

A field experiment was conducted at College farm, Professor Jayashankar Telangana State Agricultural University, Rajendranagar, Hyderabad during 2020-21 and 2021-22 to assess the influence of paddy residue management practices at different fertility levels on certain growth parameters and the yield of rabi maize succeeding kharif rice in a strip plot design. The growth analysis indicated that the leaf area index, crop growth rate, net assimilation rate and leaf area duration remained the same with residue management practices at 0-30 DAS and 30-60 DAS but between 60 DAS-harvest, maize leaf area index (LAI), crop growth rate (CGR), net assimilation rate (NAR) and leaf area duration (LAD) was significantly increased by incorporation of crop residues treated with microbial consortia and SSP. Different fertility levels affected leaf area index, crop growth rate and leaf area duration at all the growth intervals whereas net assimilation rate remained unaffected. Interaction effect of residue management practices and fertility levels on leaf area index, crop growth rate, net assimilation rate and leaf area duration was found non significant at 0-30 DAS and 30-60 DAS, while at 60 DAS-harvest integration of residues and microbial consortia along with chemical fertilizers resulted in a significant increase of LAI, CGR and LAD with no significant improvement in NAR. In 2020-21 and 2021-22, the grain yield and straw yield were higher in the incorporation of crop residues treated with microbial consortia and single super phosphate (SSP) in combination with 125 % recommended dose of fertilizers (RDF) which was on par with 100% RDF and 75 % RDF and was significantly superior over other treatments.

Potential of indigenous ligno-cellulolytic microbial consortium to accelerate degradation of heterogenous crop residues.

Indigenous microbial diversity has potential for rapid decomposition of residue through enzyme activities that is alternative, effective, and environment friendly strategy to accelerate degradation of lignocellulose in agricultural residues and make composting process economically viable. Keeping this view, the main objective of the present study was isolation and characterization of lignocellulosic degrading microbial diversity from long-term residue management practice experiments and to develop potential microbial consortium for rapid degradation of lignocellulosic biomass. In this study, twenty-five bacteria, nine fungi, and four actinomycetes isolates were obtained from the soil samples of different residue management fields from Ludhiana, Punjab, India. All isolates were qualitatively and quantitatively screened for enzyme activities, i.e., cellulase, xylanase, laccase, and lignin peroxidase. On the basis of quantitative estimation of enzyme activities, 3 fungal (S1F1, S2F4, and S6F9), 2 actinomycetes (S1A1 and S6A4), and 2 bacterial strains (S6B16 and S6B17) were further selected for in vitro bio-compatibility assay. Selected bio-compatible microbial strains were identified as Streptomyces flavomacrosporus (S6A4), Aspergillus terreus (S2F4), and Bacillus altitudinis (S6B16) through 16S rRNA and 18S rRNA sequencing. Furthermore, single and developed microbial consortium (S6B16 + S6A4 + S2F4) were screened for quantitative estimation of cellulase, xylanase, laccase, and lignin peroxidase enzymes with 23 biochemically different cereal, legume, and oil seed crop residues for optimization of enzyme activities at different time intervals. Results revealed that Vigna radiata followed by Cajanus cajan and Arachis hypogaea straw residue powder @ 1% in culture broth are a promising carbon source for B. altitudinis, S. flavomacrosporus, and A. terreus to produce higher ligno-cellulolytic microbial degrading enzymes due to variable range of carbon (C):nitrogen (N) ratio and higher ligno-cellulolytic content in the studied crop residues. Thus, the application of indigenous microbial consortium with efficient lignocellulose hydrolysis enzyme machinery might be an attractive alternative for ex situ crop residue management practices under sustainable manners.

Effect of Paddy Straw Incorporation and Nitrogen Levels on Yield and Nutrient Uptake by Mustard (Brassica juncea L.)

Burning of crop residues results in immense loss to soil fertility, in addition to this burning causes greenhouse gas emissions into atmosphere thereby disturbs the environment. A Field experiment was conducted to ascertain the crop residue and fertilizer management practices on yield and nutrient uptake of mustard at Regional Agricultural Research Station (RARS), Polasa, Jagtial situated in Northern Telangana Zone of Telangana State during rabi, 2020-21. Grain yield, nutrient content and nutrient uptake were significantly influenced by crop residue and fertilizer management practices. Highest grain and stover yield of 1194 and 2654 kg ha-1 were recorded, when 20 % excess nitrogen was applied than RDN along with residue incorporation. Nutrient uptake was significantly higher in burning treatment during initial stages of crop growth later more uptakes were observed in residue incorporation treatments. Among the treatments lowest yields and nutrient contents (N and P) were recorded in residue burning treatments. This study concluded that, instead of burning, paddy straw was to be incorporated along with 20% excess nitrogen to obtain better yields and nutrients uptake in succeding mustard crop.

Long-term effects of barley residue managements on soil hydrophysical properties in north-western Iran

The cold semi-arid cropping system is facing soil degradation, climate variability, and drought. For this reason, crop residue management is critical to soil and water conservation and the sustainability of farmers' livelihood. This study was conducted to test the hypothesis that in a cold semi-arid climate, the hydraulic properties of soil can be significantly affected by long-term crop residue management. To test this hypothesis, we investigated the changes in soil hydraulic properties (saturated hydraulic conductivity (Ks), soil water retention (SWR), cumulative infiltration (CI), parameters of van Genuchten SWR (θs, θr, α, and n), and Philip's equation indices (sorptivity and A) following long-term (five years) crop residue management. There were three treatments: (i) complete removal of crop residue from the soil surface (T1), (ii) incorporation of crop residue into the soil after harvest (T2), and (iii) burning of crop residue on the field (T3). The results showed that the Ks value was higher (p ≤ 0.05) in T2 (incorporation, 0.36 cm min−1) than in T1 (removal, 0.30 cm min−1) or T3 (burning, 0.26 cm min−1). Also, the α value was lower (p ≤ 0.05) in incorporation treatment (0.032 cm−1) than in removal treatment (0.042 cm−1) or burning treatment (0.048 cm−1). The value of S (1.72 cm min-0.5) in incorporation treatment differed significantly (p ≤ 0.05) from that of removal (1.09 cm min-0.5) and burning (1.31 cm min-0.5) treatments. Noticeable differences in soil water retention were greater at low soil water suction heads in the SWR. The differences between the SWR of treatments at low suction heads grew over time. A little difference was observed between the SWR of treatments in high suction heads. The cumulative infiltration curve for incorporation treatment differed from that obtained for removal and burning treatments, with no sizable differences observed between removal and burning over five years. The results of this study indicated that the increase in soil organic matter (SOM) for burning reduced the negative effects of burned barley residue on soil hydraulic properties to some extent. Thus, burning residues may have a little negative impact on a sustainable cropping system. The results revealed that the incorporated barley residue increased the infiltration of water into the soil more than other residue management practices in the cold semi-arid region.

Effect of various Maize Crop Residue Management Practices and Fertility Levels on Physiological Growth Parameters of Direct Seeded Rice in Rice-maize Sequence

Effect of various Maize Crop Residue Management Practices and Fertility Levels on Physiological Growth Parameters of Direct Seeded Rice in Rice-maize Sequence

Tillage, green manure and residue retention improves aggregate-associated phosphorus fractions under rice\u2013wheat cropping

The sustainability of the rice–wheat system is threatened due to the deterioration of soil health and emergence of new challenges of climate change caused by low nutrient use efficiency and large scale burning of crop residues. The conservation agriculture based on tillage intensity, crop residue retention and raising green manuring (GM) crops during the intervening period between wheat harvest and rice establishment offers opportunities for restoration of phosphorus (P) dynamics and stimulate phosphatase activities within the macro-and micro-aggregates. Phosphorus and phosphatase activities in the soil aggregates affected by different residue management practices remain poorly understood. Thus, soil samples were obtained after a five-year field experiment to identify the effect of tillage, green manure and residue management on aggregate-associated phosphorus fractions. Four main plot treatments in rice included combination of wheat straw and GM were conventional till puddled transplanted rice (PTR) with no wheat straw (PTRW0), PTR with 25% wheat stubbles retained (PTRW25), PTR without wheat straw and GM (PTRW0 + GM), and PTR with wheat stubbles and GM (PTRW25 + GM). Three sub-plots treatments in the successive wheat crop were conventional tillage (CT) with rice straw removed (CTWR0), zero tillage (ZT) with rice straw removed (ZTWR0) and ZT with rice straw retained as surface mulch (ZTWR100). Results of the present study revealed significantly higher phosphorus fractions (HCl-P, NaHCO3-Pi and NaOH-Po) in treatment PTRW25 + GM and ZTWR100 compared with PTRW0/CTWR0 within both macro- and micro-aggregates. The total phosphorus (P), available P, alkaline phosphatase and phytin-P were significantly higher under ZTWR100 than CTWR0. The principal component analysis identified NaOH-Po, NaHCO3-Pi and HCl-P as the dominant and reliable indicators for evaluating P transformation within aggregates under conservation agriculture-based practices.

Environmental and Health Impacts of Crop Residue Burning: Scope of Sustainable Crop Residue Management Practices.

The burning of crop residue in the open field has become a significant concern for climate change mitigation efforts worldwide. This practice has led to air quality impairment, smog, haze, heat waves, and different health problems. These could be avoided by adopting sustainable crop residue management practices (SCRMPs) and enabling farmers to engage in SCRMPs. Assessing the health effects at the household level is critical for understanding this problem and finding a solution. Using the primary dataset of 420 farmers from Punjab, Pakistan, we estimated the incurred impacts and costs of crop residue burning. We calculated the health and environmental benefits associated with adopting SCRMPs by comparing the two groups of farmers (adopters and non-adopters). Furthermore, we used a propensity score matching technique to measure the causal impact of SCRMPs adoption on health costs. The findings showed that a surprisingly large number of farmers are all aware of the adverse effects of residue burning, and many do not burn crop residues and instead use SCRMPs. This study found that households with chronic and non-chronic diseases become acute, and the severity increases during the burning period. They spend USD 13.37 to USD 8.79 on chronic and non-chronic diseases during the burning season, respectively. Consequently, the use of SCRMPs has a positive effect on healthcare costs. Our study findings highlight the meaningful implications for developing a new policy to promote the sustainable utilization of crop residues and enhance their adoption in Pakistan.

Evaluating the trade-offs and sustainability of minimum tillage and crop-residue addition for food production in the dryland tropics

A long-term study was carried out at ICRISAT farm, Patancheru (India) during rainy (kharif) season 2009–18with an objective to evaluate impact of tillage (minimum/conventional) and residue (addition/removal) management practices on production capacity and sustainability of maize-chickpea sequential and maize+pigeonpea intercropping systems. The experiment was laid out in spilt plot design with 4 replications. The effects of residue addition were inconsistent till the third year of experiment. However, yield benefits from residue addition became apparent fourth year onwards. After 7 years, residue addition showed significant yield benefits to the tune of 9–25% during 2016–17 (8th cropping cycle) and 18–31% during 2017–18 (9th cropping cycle) in both cropping systems. Residue addition also resulted in additional net income of `16,900/ha to `22,980/ha compared to no-residue addition. Minimum tillage in general tended to result in yield loss over normal tillage since beginning. During 8th and 9th cropping cycles, there was net annual loss up to `5400/ha under minimum tillage. Alongside productivity and economic benefits, at the end of 8th year i.e. 2016–17, residue addition showed improved soil health and sequestered around 300 kg carbon/ha/year.

Impact of Rice Residue Management Practices on Environment, Productivity and Economics of Wheat: A Review

Rice-Wheat (RW) is a major cropping system followed in Indo-Gangetic Plains of India. This cropping system popularised with mechanisation of both mentioned crops. Increase in mechanisation, particularly use of combined harvesting enables harvesting of rice in a very short span of time but it leaves behind a large amount of crop residue. Ex-situ residue management of this voluminous residue is not feasible and economical to the farmer. Burning of rice residue is a common practise in India to manage the rice residue because of its low economic use, which causes serious air pollution and nutrient losses. Sustainability of RW system is at risk due to soil degradation and poor residue management practices. Proper in-situ residue management is of utmost importance as crop residue contains significant amount of nutrients and it can improve soil physical, chemical and biological health because of huge amount of organic carbon added to the soil. Various soil properties, wheat productivity, economics and the environment are highly influenced by the rice residue management practices adopted. In this review, the authors have discussed impact of different rice residue management practices and wheat sowing methods on wheat productivity, economics, soil properties and the environment.

Field Crop Residue burning Induced Particulate Pollution in NW India – Policy Challenges & Way Forward

The study aims to provide insights into the effectiveness of numerous policy interventions to curb FCRB-induced air pollution in NW India. The problem is addressed by examining the trend and co-existence of VIIRS retrieved thermal anomalies in NW states and PM2.5 concentrations in New Delhi during the two harvesting seasons (April-May & Oct-Nov) over the period 2014-2020. The findings reveal that various governmental measures that primarily revolve around sustainable residue management practices cannot holistically curb the stubble burning practice in NW India and the related air pollution in neighboring states. The study suggests that besides the short-term residue management measures, crop diversification or discontinuing dual rice-wheat cultivation is the only long term measure to regulate widespread stubble burning and the deteriorating air quality.

English

Crop residues' inappropriate management is the main constraint causing the decline in soil fertility and crop yields in Burkina Faso. This study was conducted at the Farako-Bâ Research Station from 2014 to 2019 to assess the effects of crop residue management to improve the sustainability of the cotton-cereal based production systems. The experimental design was complete randomized blocks of Fischer with four replications. Three different crop residue management practices were investigated: (i) Crop residue exportation and conventional tillage (T1); ii) Composted crop residues and conventional tillage (T2); and (iii) Crop residues used for soil mulching and no-tillage (T3). Soil chemical characteristics and crop yields were assessed as parameters in this study. Crop yields were improved by 17 to 34% on maize, from 18 to 38% on cotton and from 6 to 14% on sorghum, respectively, with residues recycled into compost (T2) and residues used for soil mulching (T3) compared to residues exported (T1). Crop residue management and soil tillage technics significantly increased the yields of maize, sorghum, and cotton after the first three years of experimentation. Soil chemical properties were not statistically influenced, except for SOM, nitrogen, and available K content. The highest decrease in soil carbon content induced by crop residue exportation (T1) should not be recommended to farmers. Key words: Crop residues, tillage, soil fertility, cotton-cereals, yield, Burkina Faso.

Soil carbon and nitrous oxide dynamics in corn (Zea mays L.) production under different nitrogen, tillage and residue management practices

Reducing tillage frequency and intensity and returning crop residues to the soil are two agricultural management practices to increase soil organic carbon (SOC). Timing and rates of nitrogen fertilizer, coupled with tillage methods and residue incorporation, can also influence nitrous oxide emissions. In this study, we used measured data from a long term (23 years) tillage and residue management experiment, under intensive grain corn production, together with the DNDC (DeNitrification-DeComposition) process-based model, to ascertain the most effective fertilizer and tillage management practices to reduce nitrous oxide emissions and nitrate leaching, and increase soil carbon stocks. The field experiment consisted of no-till [NT], reduced [RT], and conventional tillage [CT], with and without corn residue return. After calibration and validation, using field observed data, the DNDC model was run with 108 management scenarios (six N application rates, spring single N fertilization, spring split N fertilization and fall fertilization, three tillage practices and two residue-return options). N application rate was predicted to be a significant driver for corn yield, SOC sequestration, N2O emissions and nitrate leaching, indicating the need to identify a critical N rate to both optimize production and achieve sustainability goals. Split (vs. single) N application did not significantly affect corn yield, nitrate leaching, N2O emissions or SOC, while fall fertilization should be avoided due to greater nitrate leaching and higher N2O emissions as well as lower crop yield. Although stimulating N2O emissions, both NT and residue return are recommended for their ability to enhance SOC stocks. Results of this study can be used for policy development regarding carbon sequestration and GHG emissions for intensive grain cropping systems in the humid regions of North America.

Spatiotemporal variation patterns and aggregation of crop residue burning at county scale in Northeast China

Crop residue burning (CRB) has been a major environmental concern in key agricultural regions of China. To reveal spatiotemporal patterns of CRB events, a county-level assessment in Northeast China was conducted using Moderate Resolution Imaging Spectroradiometer (MODIS) thermal anomalies and land cover data. The results revealed that cropland fire occurrence increased significantly from 2003 to 2019, and annual CRB occurrence from 2014 to 2019 was significantly higher than that from 2003 to 2013. The majority of detected CRB events occurred in spring and autumn, accounting for 58.50% and 28.98% of the total cropland fires, respectively. The time scan statistics showed that CRB events lasted for approximately 40 days each year and were more severe in spring than autumn. The number of cropland fires monitored by Terra and Aqua satellites was relatively more balanced, accounting for 49.74% and 50.26% of the total, respectively, indicating that farmers may intentionally burn crop residue at night. The counties with higher CRB intensity were mainly in the Songnen Plain, Sanjiang Plain, and along the main stream of the Liaohe River. The Moran’s I value of 0.054 to 0.452 for CRB intensity demonstrated a strong spatial autocorrelation at the county level. The local autocorrelation Getis-Ord showed 86 counties with significant hot spots and 91 counties with significant cold spots. The county-level temporal and spatial patterns of CRB events may be the results of policies and socio-economic conditions. This study could provide support for identifying the influencing factors of CRB and offer suggestions for crop residue management practices in this agriculture-dominant region.

Modelling greenhouse gas emissions of cacao production in the Republic of C\xf4te d\u2019Ivoire

The current expansion of cacao cultivation in the Republic of Côte d’Ivoire is associated with deforestation, forest degradation, biodiversity loss and high greenhouse gas (GHG) emissions. Global concerns about emissions that are associated with tropical commodity production are increasing. Consequently, there is a need to change the present cacao-growing practice into a more climate-friendly cultivation system. A more climate-friendly system causes lower GHG emissions, stores a high amount of carbon in its standing biomass and produces high cacao yields. GHG emissions and carbon stocks associated with the present cacao production, as assessed in 509 farmers’ fields, were estimated by using the Perennial GHG model and the Cool Farm Tool. On average, the production of 1 kg cacao beans is associated with an emission of 1.47 kg CO2e. Deforestation contributed largely to GHG emissions, while tree biomass and residue management contributed mainly to carbon storage. The collected data combined with the model simulations revealed that it is feasible to produce relatively high yields while at the same time storing a high amount of carbon in the standing biomass and causing low GHG emissions. The climate-friendliness of cacao production is strongly related to farm management, especially the number of shade trees and management of residues. Calculated emissions related to good agricultural practices were 2.29 kg CO2e per kg cacao beans. The higher emissions due to the use of more agro-inputs and other residue management practices such as recommended burning of residues for sanitary reasons were not compensated for by higher yields. This indicates a need to revisit recommended practices with respect to climate change mitigation objectives.