Straw Retention Research Articles

STABLE CARBON ISOTOPE FOR EVALUATING SOIL ORGANIC CARBON BETWEEN RICE-CORN ROTATION AND CORN MONOCROPPING

Soil organic carbon (SOC) is a significant component that plays an important role in soil fertility and crop sustainable production. This study investigated SOC in soil profiles of rice-corn rotation and corn monocropping using a stable carbon isotope of SOC (δ13CSOC) technique. The soil samples were collected from two plots of rice-corn rotation and corn monocropping fields. Soil sampling was conducted in Tak province, involving the collection of 25 soil cores per plot down to a depth of 50 cm. Each soil profile was further segmented into ten depth layers: 0-5 cm, 5-10 cm, 10-15 cm, 15-20 cm, 20-25 cm, 25-30, 30-35, 35-40, 40-45, and 45-50 cm. The collected soil samples were then subjected to air drying, pulverization, and sieving through a 200-mesh sieve. The δ13CSOC in rice-corn rotation ranged from -28.41‰ to -23.72‰ while corn monocropping was -24.59‰ to -15.83‰. The results revealed that the values of δ13CSOC for each soil profile gradually increased with soil depth. Since δ13CSOC levels were negatively correlated to SOC. Therefore, SOC decreased with increasing soil depth in both the rice-corn and corn fields. However, significantly higher SOC contents were observed in rice-corn rotation rather than in corn monocropping fields (p < 0.05). SOC contents were higher in soil with rice straw retention than without rice residues. The rotation of rice-corn practice could potentially retain organic carbon in soil better than corn monocropping.

Effects of Fallow Season Water and Straw Management on Methane Emissions and Associated Microorganisms

The effects of fallow season water and straw management on methane (CH4) emissions during the fallow season and the subsequent rice-growing season are rarely reported, and the underlying microbial mechanisms remain unclear. A field experiment was conducted with four treatments: (1) fields flooded in both the fallow and rice seasons (FF), (2) fields drained in the fallow season and flooded in the rice season (DF), (3) FF with straw retention (FFS), and (4) DF with straw retention (DFS). The CH4 emissions in fields under different water and straw treatments were monitored using the static closed chamber method. Methanogenic and methanotrophic communities in these fields were examined using terminal restriction fragment length polymorphism (T-RFLP) analysis based on the mcrA gene and pmoA gene encoding methyl coenzyme M reductase and particulate methane monooxygenase, respectively. The results showed that CH4 emissions were significantly affected by water management, straw retention, season, and their interactions. Over 80% of CH4 emissions occurred during the rice season. Field drainage during the fallow season reduced CH4 emissions by 47.0% and 53.8% with and without straw during the rice season, respectively. Water management altered the abundance and composition of methanogens and methanotrophs, whereas the effects of straw retention were less pronounced. The quantitative polymerase chain reaction (qPCR) assay revealed that field drainage in the fallow season decreased the mcrA gene abundance by 30.0% and 23.2% with and without straw in rice season, respectively, and increased the pmoA gene abundance by 108.9% and 213.7% with and without straw in rice season, respectively. CH4 flux was significantly positively associated with mcrA gene copy number and the ratio of mcrA to pmoA gene copy number, whereas it was significantly negatively correlated with the pmoA gene copy number. Results indicated that fallow drainage greatly decreased CH4 emission not only during the fallow season but also during the subsequent rice season by altering the community composition of methanogens and methanotrophs. These findings provide scientific insight into the role of water and straw management in controlling CH4 emissions through microbial community dynamics.

Long-Term Minimum Tillage and Straw Retention Promote Macroaggregate Formation, Carbon and Nitrogen Sequestration under Wheat-Maize Rotation in Northern China

Conservation tillage is believed to promote soil aggregate stability, carbon (C) and nitrogen (N) sequestration, but the underlying mechanisms remain unclear. In this study, soil samples from an 18-year experiment including conventional tillage with straw removal (CT), deep scarification with straw mulching (DS), and no-tillage with straw mulching (NT) were used to obtain different fractions based on a comprehensive wet-sieving method of aggregate and particle size. The results showed that NT and DS increased soil organic carbon (SOC) and N by 9.3–16.4% and 10.8–25.8%, respectively, in addition to increasing the weight proportion of macroaggregates and the contribution of macroaggregate-associated C and N to total SOC and N. The C change in the total POM accounted for 77.4% and 79.9% of the total SOC increase by NT and DS, while the MAOM only accounted for 29.2% and 25.2%, respectively. Meanwhile, microaggregates-within-macroaggregates accounted for 96.9% and 90.5% of the SOC increase by NT and DS, respectively. The total SOC and N were positively correlated with the C and N of the macroaggregates and subfractions. In conclusion, the formation of macroaggregates drives soil C and N sequestration under conservation tillage, and POM and mM were important functional pools in this process.

Phosphorus application under continuous wheat-cotton straw retention enhanced cotton root productivity and seedcotton yield by improving the carbohydrate metabolism of root

ContextStraw retention could reduce phosphorus (P) application without decreasing seedcotton yield but related physiological mechanisms were unclear. Cotton root is the first organ to sense the changes in soil environment, and its growth and development, especially carbohydrate metabolism, significantly affected the formation of seedcotton yield. Therefore, it is necessary to explore the responses of cotton root carbohydrate metabolism to straw retention combined with P application. ObjectiveThis study was to investigate the effects of straw retention combined with P application on root carbohydrate metabolism and its relationship with seedcotton yield. MethodsA field experiment (2020–2022) was conducted to evaluate the changes in seedcotton yield, cotton canopy apparent photosynthesis rate (CAP), biomass, root productivity, root carbohydrate contents and related enzyme activities under different straw management [removal (S0), retention (S1)] and P rates (0, 100, 200 kg P2O5 ha−1). ResultsStraw retention and P application both increased seedcotton yield and had a significant interaction effect on it. In the 5th-7th year of straw retention, straw retention reduced 24 %-26 % P application to reach a similar yield of S0 with 100 kg P2O5 ha−1. Analyzing the reasons: (1) Straw retention combined with P application increased cotton CAP, providing adequate assimilates for cotton development; (2) Straw retention combined with P application promoted the utilization of root carbohydrates, thereby increasing root productivity and seedcotton yield. Specifically, compared with S0 without P, S1 combined with P application increased the enzyme activities related to carbohydrate metabolism, especially sucrose synthase (7.6 %-59.4 %) and acid invertase (3.9 %-58.6 %), which reduced sucrose (3.3 %-32.2 %) and starch (4.3 %-28.7 %) contents at the peak boll setting stage. Efficient utilization of sucrose and starch enhanced root productivity, the ratio of root to shoot (R/S) reduced by 2.7 %-21.6 %, while the boll loading of root system (BLR) and boll capacity of root system (BCR) increased by 0.6 %-39.2 % and 3.1 %-50.6 % at the boll opening stage, respectively, favoring the formation of seedcotton yield. Furthermore, when the R/S, BLR, and BCR reached 0.12, 0.81 boll g−1, and 4.33 g g−1, cotton harvested the maximum theoretical yield of 3780, 3774, and 4069 kg ha−1, respectively. ConclusionsStraw retention combined with P application increased root productivity and seedcotton yield by promoting the utilization of root carbohydrates. ImplicationsThis study revealed the internal mechanism for straw retention combined with P application to affect seedcotton yield from the angle of root carbohydrate metabolism and provided a theoretical basis for rationally reducing P fertilizer under straw retention.

Application of fungal inoculants enhances colonization of secondary bacterial degraders during in situ paddy straw degradation: a genomic insights into cross-domain synergism.

Rice cultivation generates huge amounts of on farm residues especially under mechanical harvesting. Paddy straw being recalcitrant hinders sowing of upcoming rabi crops like wheat and mustard. Non-environmental sustainable practice of on-farm burning of the paddy residues is being popularly followed for quick disposal of the agro-residues and land preparation. However, conservation agriculture involving in situ residue incorporation can be a sustainable option to utilize the residues for improvement of soil biological health. However, low temperature coupled with poor nitrogen status of soil reduces the decomposition rate of residues that may lead to nitrogen immobilization and hindrance in land preparation. In this direction, ecological impact of two approaches viz priming with urea and copiotrophic fungus-based bioformulation (CFB) consisting of Coprinopsis cinerea LA2 and Cyathus stercoreus ITCC3745 was studied for in situ degradation of residues. Succession of bacterial diversity was deciphered through high throughput whole metagenomic sequencing along with studies on dynamics of soil microbial enzymes. Treatments receiving CFB (T1) and urea (T2) when compared with bulk soil (absolute control) showed an increase in richness of the microbial diversity as compared to control straw retained treatment control (T3). The β diversity indices also indicated sufficient group variations among the treatments receiving CFB and urea as compared to only straw retained treatment and bulk soil. Priming of paddy straw with CFB and urea also induced significant rewiring of the bacterial co-occurrence networks. Quantification of soil ligno-cellulolytic activity as well as abundance of carbohydrate active enzymes (CAZy) genes indicated high activities of hydrolytic enzymes in CFB primed straw retention treatment as compared to urea primed straw retention treatment. The genomic insights on effectiveness of copiotrophic fungus bioformulation for in situ degradation of paddy straw will further help in developing strategies for management of crop residues in eco-friendly manner.

Soil quality associated with microbial community characteristics and dominant taxa across different tillage practices

AbstractDespite conservation tillage being a promising strategy to mitigate soil degradation, the intricate role of microbial communities in shaping soil quality over long‐term tillage remains poorly understood. The study aimed to investigate the microbial mechanisms governing the soil quality index (SQI) and maize yield under different tillage practices spanning 13 years, including no‐till without straw retention (NT0), no‐till with straw retention (NTSR), plough tillage with straw retention (PTSR), and rotary tillage with straw retention (RTSR). The findings revealed that NTSR improved the SQI index by 22.4% and 11.3% higher than PTSR and RTSR, respectively, within the 0–10 cm soil layer. This improvement was correlated with an increase in maize yield (R2 = 0.39, p < 0.05). PERMANOVA analysis confirmed that both soil depth and tillage practices significantly impacted the composition of microbial communities (p < 0.05). Furthermore, conservation tillage, compared to PTSR and RTSR, increased the abundance of arbuscular mycorrhizal symbiosis by 78.6%–460.3% but decreased the saprophytic fungal abundance by 27.5%–28.3%. Soil quality was notably influenced by the interaction between bacterial and fungal communities. The presence of bacterial‐dominated Module 2 was associated with decreased soil quality in the 0–10 cm soil depth (r = −0.47, p < 0.01). This study emphasizes the pivotal role of microbial diversity and dominant taxa in driving soil quality after long‐term conservation tillage practices. Understanding these mechanisms is crucial for establishing farmland management to achieve agricultural and ecological sustainability in the face of climate change and soil degradation challenges.

No-tillage with straw retention influenced maize root growth morphology by changing soil physical properties and aggregate structure in Northeast China: A ten-year field experiment

Conservation tillage, particularly the implementation of no-tillage and straw retention (NTS), has been proposed as an effective practice to enhance soil structure and improve soil quality in Northeast China. However, the impact of NTS on maize (Zea mays L.) root growth morphology and the influence of tillage practices on maize root morphology through soil physical properties and structure in Northeast China remain understudied. To address this knowledge gap, a continuous ten-year experiment was conducted to assess the effects of NTS on soil physical properties, aggregate structure, maize root morphology, and their interconnections. Our findings demonstrate that the NTS treatment significantly increased soil water content and soil bulk density at depths of 0–5 cm (1.6%) and 5–10 cm (2.2%), while decreasing soil porosity at depths of 0–5 cm (1.4%) and 5–10 cm (2.0%) compared to conventional tillage (CT). Additionally, NTS resulted in a higher content of soil macro-aggregates (> 0.25 mm) and improved soil aggregate stability compared to CT. Notably, root length, root surface area, root volume, and root biomass in the NTS treatment were 6.04%, 22.15%, 10.04%, and 9.29% higher than those in CT, respectively. However, there was no significant difference in root diameter between the two tillage practices. These results reveal that NTS induces alterations in soil physical properties, aggregate size distribution and aggregate stability, thereby affecting maize root growth morphology.

Straw Retention with Reduced Fertilization Enhances Soil Properties, Crop Yields, and Emergy Sustainability of Wheat-Soybean Rotation.

Cereal + legume rotation is an integrated system that facilitates soil fertility and sustainable agricultural production. However, research on the management compatibility affecting soil physico-chemical properties yields overall agro-ecosystem sustainability, but profitability is lacking, especially under straw retention and potential reductions in fertilizer application. An 11-year field experiment investigated three treatments: no straw retention + traditional mineral fertilization (TNS), straw retention + traditional mineral fertilization (TS), and straw retention + reduced mineral fertilization (DS). Compared with TNS, TS significantly improved soil physico-chemical properties, including macro-aggregates (R > 0.25 mm), porosity, field water capacity (FWC), soil organic carbon (SOC) storage, total nitrogen storage, microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN) by 17.3%, 3.2%, 13.0%, 5.5%, 3.2%, 15.5%, and 13.8%, respectively. TS also significantly increased total (wheat + soybean) yields (TYs), economic profits, and emergy sustainability index (ESI) by 15.8%, 25.0%, 3.7 times that of TNS, respectively. Surprisingly, compared with TS, DS further significantly improved R > 0.25 mm, porosity, FWC, SOC storage, MBC, MBN, TY, economic profits, and ESI by 11.4%, 1.5%, 6.1%, 3.0%, 10.6%, 7.2%, 5.7%, 11.1%, and 36.5%, respectively. Overall, retaining straw with reduced fertilization enhances soil properties, yields, and emergy sustainability in wheat-soybean rotation systems.

Effects of Short-Term Tillage on Rhizosphere Soil Nitrogen Mineralization and Microbial Community Composition in Double-Cropping Rice Field.

Soil extracellular enzyme plays a vital role in changing soil nitrogen (N) mineralization of rice field. However, the effects of soil extracellular enzyme activities (EEA) and microbial community composition response to N mineralization of rice field under short-term tillage treatment needed to be further explored. In this study, we investigated the impact of short-term (8-year) tillage practices on rhizosphere soil N transformation rate, soil enzyme activities, soil microbial community structure, and the N mineralization function gene abundances in double-cropping rice field in southern China. The experiment consisted of four tillage treatments: rotary tillage with crop straw input (RT), conventional tillage with crop straw input (CT), no-tillage with crop straw retention (NT), and rotary tillage with all crop straw removed as a control (RTO). The results indicated that the rhizosphere soil N transformation rate in paddy field under the NT and RTO treatments was significantly decreased compared to RT and CT treatments. In comparison to the NT and RTO treatments, soil protease, urease, β-glucosaminidase, and arginase activities were significantly improved by the CT treatment, as were abundances of soil sub, npr, and chiA with CT and RT treatments. Moreover, the overall diversity of soil bacterial communities in NT and RTO treatments was significantly lower than that in RT and CT treatments. Soil chitinolytic and bacterial ureolytic communities were also obviously changed under a combination of tillage and crop straw input practices.

Tillage and Straw Management Practices Influences Soil Nutrient Distribution: A Case Study from North-Eastern Romania

Tillage practices govern crop quality and quantity through soil nutrient availability and crop root systems. A deeper knowledge of the impact of conservation tillage on soil chemical characteristics (such as pH, soil organic carbon, macro and micronutrient storage and distribution) is required for both the promotion of agricultural sustainability and environmental preservation. This study assesses the changes in soil features and properties in the context of a long-field experiment with different tillage systems and straw management practices. Research findings revealed that compared with conventional tillage (CT) conservative tillage with partial straw retention (MT) and no-tillage with straw mulching (NT) substantially boosted the organic carbon (OC) (by 6–19%), total nitrogen (TN) (by 2–12%), and available potassium content (AK) (by 2–5%), in 0–30 cm soil depth. However, the stratification trend was observed for available macro and micronutrient content (Zn, Fe, Mn) in both conservative management practices. The concentration of Cu indicates a constant pattern through a 0–30 cm soil profile with a higher concentration under MT (1.41 mg kg−1) compared to NT (1.10 mg kg−1). In particular, the results failed to establish if conservation tillage can increase the total phosphorus (TP) and potassium content (TK), where only in surface 0–10 cm an increase was observed. This research also suggested that the X-ray fluorescence analysis (XRF) of total micronutrient content (Zn, Cu, Fe, Mn) is minimal or unpredictable with no substantial differences between the tillage systems and straw return management practices. These findings suggest that conservation tillage in north-eastern Romania might be optimal to maintain soil quality status and sustain high yields.

Effects of Straw Returning on Soil Aggregates and Its Organic Carbon and Nitrogen Retention under Different Mechanized Tillage Modes in Typical Hilly Regions of Southwest China

Tillage modes and straw returning influence soil aggregate stability and the distribution of organic carbon (C) and nitrogen (N) in aggregates of different particle sizes. In the typical hilly regions of southwest China, the predominant soil type is purple soil, characterized by heavy texture and high stickiness, with relatively lower soil fertility compared to other soil types. The improper use of fertilizers and field management practices further exacerbates soil compaction. However, abundant straw resources in the region provide an opportunity for comprehensive straw utilization. The effective utilization of straw resources is of significant importance for stabilizing agricultural ecological balance, improving resource utilization efficiency, and alleviating ecological pressure. Previously, most studies have focused on the impact of different mechanized tillage systems on the physical and chemical properties of soil in hilly areas, while research on the preservation of water-stable aggregates’ organic C and N content remains limited. In this study, the soil properties of fields under a winter pea–summer corn rotation for two years were studied with regards to the effects of straw returning on its water-stable aggregate distribution, macroaggregate content (R0.25), mean weight diameter (MWD), geometric mean diameter (GMD), and the organic C and N content in soil aggregates of different particle sizes and at different depths. The effects of five different tillage modes were assessed, namely rotary tillage with straw mixed retention (RTM), conventional tillage with straw burial retention (CTB), no-tillage with straw covered retention (NTC), subsoiling with straw covered retention (STC), and no-tillage without straw retention (NT). Based on the study results, under different tillage modes, straw returning effectively enhanced the soil organic carbon (SOC) and total nitrogen (TN) reserves at the plow layer (0–30 cm), SOC increased by 17.2% to 88%, and TN increased by 8.6% to 85.9%. At the same time, the content of 0.25–2 mm aggregates increased under the straw-return treatments under different tillage patterns. The NT treatment had the lowest R0.25 and MWD and GMD values for soil aggregates at different depths, which were significantly different (p < 0.05) from the other treatment modes. The correlation coefficients between SOC and soil aggregate stability indices ranged from 0.68 to 0.90, with most of them showing highly significant positive correlations (p < 0.01). In conclusion, straw returning under different tillage systems has improved soil aggregate stability and promoted soil structure stability. Specifically, the STC treatment has shown more pronounced effects on soil improvement in the upper soil layer of the hilly regions in southwest China, while the RTM treatment is beneficial for improving the lower soil layer. Therefore, the comprehensive experimental results indicate that the combination of STC and RTM treatments represents the most promising mechanized tillage and straw returning practices for the hilly regions in southwest China.

Evaluation of straw and agricultural policy impacts on the sustainability of the straw-based bioeconomy with an agent-based model

The use of straw as feedstock for the bioeconomy constitutes an important opportunity to fulfill the societal demand for biobased products and reduce the externalities incurred in the utilization of non-waste resources and alternative waste management methods. However, the insufficient supply of raw material and high reliance on government support have constrained further expansion of the industry. Additionally, the evaluation of policies is hindered by the complexity of bioeconomy systems, where multiple entities generate patterns that are difficult to analyze with conventional tools. We developed an agent-based model based on the Social-Ecological Systems framework and mixed methods to analyze the effect of various straw and agricultural policy scenarios on farmers, straw operators, and industrial plants, and their subsequent impacts on the socioeconomic and environmental outcomes of the straw-based industry. The results indicate that the combined use of straw retention and straw collection methods achieves optimal outcomes for sustainability, and that further adoption of straw collection in the study area can be facilitated by policies targeted towards farmer awareness, efficiency of operations, and market demand. The analysis also shows that policy strategies have a considerable influence over the distribution of economic value among stakeholders. Finally, this study demonstrates the usefulness of this modeling approach for the analysis of bioeconomy systems with multiple stakeholders, policy measures, and sustainability goals. Overall, these finding illustrate the implications of different policy and straw management approaches for the straw-based industry, and provide a useful guideline for the modeling of circular bioeconomy systems in China and elsewhere.

Assessing the impacts of climate change on crop yields, soil organic carbon sequestration and N2O emissions in wheat–maize rotation systems

Straw retention has been widely implemented to increase soil organic carbon (SOC) sequestration and greenhouse gas (GHG) mitigation for global agriculture. However, the combined effects of long-term straw retention on crop production, SOC sequestration and GHG emissions response to climate change remain unknown. Two nearby wheat–maize rotation field experiments in the North China Plain, combined with local weather, soil and agronomic measurements, were used to evaluate the applicability of the SPACSYS model. The model was then applied to assess the response of crop yield, SOC storage and nitrous oxide (N2O) emissions to three nitrogen fertilizer application levels (100, 200, 400 kg N ha−1) and three representative concentration pathway scenarios (RCP2.6, RCP4.5 and RCP8.5) under straw retention for the wheat–maize rotation systems during 2021–2100. In general, the model was reasonably accurate with R2 and model efficiency (EF) ranging from 0.25 to 0.96 and 0.32–0.94, respectively. Climate change decreased wheat yield by 4–39%, while maize showed a slight increase (3%) under RCP2.6 and a decrease of 1–15% under RCP4.5 and RCP8.5. The SOC storage in the 0–20 cm soil increased at a rate of 73–195 kg C ha−1 yr−1 but decreased within the upper 1 m soil at 280–390 kg C ha−1 yr−1. Climate change reduced the positive effect of SOC sequestration except in RCP2.6 and stimulated substantial N2O emissions ranging from 1–7.5 to 2.9–23.2 kg N ha−1 yr−1, consequently, the global warming potential increased from –79–2555 to 548–9357 kg CO2-eq ha−1 yr−1 under various N fertilizer application levels. This study reveals that the negative feedback under climate change with modelling approach, and extensive efforts are needed to make adaptations to ensure food production and reduce GHG emissions in the future.

Long-Term Effect of Crop Establishment Methods and Tillage Practices on Soil Physical Properties in Rice-Wheat System

ABSTRACT Rice-wheat system, the most prevalent cropping system of the Indo-Gangetic plain, nowadays poses a threat to its sustainability owing to deterioration of soil physical parameters, disposal of rice straw and declining yield trends. The present study was aimed to identify the best option of crop establishment, tillage and rice straw retention in rice-wheat system after long-term (2010–2020). The field experiment was conducted on typic Ustochrept sandy clay loam soil. Treatments comprised direct seeded rice with zero tillage (DSRZT), direct seeded rice with conventional tillage (DSRCT), direct seeded rice with reduced tillage (DSRRT) and puddled transplanted rice (PTR) in rice as main plots; and conventionally tilled without rice residue (CTW), zero tilled without residue (ZTW) and zero tilled wheat with residue retention (ZTW+R) in wheat as sub plots. The results revealed that physical parameters like bulk density and soil penetration resistance decreased while, plant available water content, infiltration and hydraulic conductivity of the soil increased significantly in DSRZT, DSRRT and ZTW+R compared to PTR and CTW. Amount of organic carbon enhanced from .42% to .55% and .34% to .39% in both 0–15 and 15–30 cm soil layers, respectively, in DSRZT compared to PTR. Aggregation status also improved in ZT-based treatments in contrast to PTR and CTW treatments. However, the average grain yield of rice was higher by 2.15–19.4% in PTR compared to DSR treatments while; ZTW+R had an advantage of 4.98% and 7.75% in contrast to CTW and ZTW, respectively, in terms of average wheat yield.

Straw retention and inhibitor application reduce the leaching risk of mineral N in no-tillage systems of Northeast China

Straw retention and inhibitor application reduce the leaching risk of mineral N in no-tillage systems of Northeast China

Straw Residual Retention on Wheat Photosynthetic Characteristics, Utilization of Water and Nitrogen, and Reactive Nitrogen Losses

Straw residual retention is an emerging and promoted practice in rain-fed northwest China, but its effect on wheat photosynthetic characteristics, the utilization of water and nitrogen, and reactive nitrogen losses is poorly understood. A two-year consecutive field experiment was conducted to investigate the impacts of residual incorporation into soil and nitrogen application on wheat nitrogen and water utilization, yield and nitrogen losses during 2018–2020. The split-plot design of two tillage systems [conventional tillage (CT), and straw residue incorporated into soil (SR)] and three nitrogen rates [0 kg ha−1 (N0), 144 kg ha−1 (N144), 180 kg ha−1 (N180)] was implemented. Our results demonstrated that compared to CT, SR significantly influenced several key metrics. Compared with CT, SR increased the wheat photosynthetic rate (Pn), transpiration rate (Tr), leaf area index (LAI), leaf total chlorophyll (Chl-total), glutamine synthetase (GS) and nitrate reductase (NR) by an average of 5.38%, 12.75%, 8.21%, 5.79%, 16.21% and 20.08%, respectively (p < 0.05). In addition, SR increased the wheat grain yield and nitrogen uptake accumulation (NUA), evapotranspiration (ET), precipitation storage efficiency (PSE), and mineral nitrogen residual after harvest (except for SR-N180 in 2019–2020), but decreased the apparent nitrogen recovery when compared with CT. However, there was an insignificant difference in the ammonia (NH3) volatilization and nitrous oxide (N2O) emissions of SR and CT. With an increase in the N-fertilization rate, the Pn and Tr, NH3 volatilization, N2O emission, mineral nitrogen residual (except for SR-N180 in 2019–2020), LAI, Chl-total (except for SR-N180 and CT-N180 in 2018–2019), GS, NR, grain yield, WUE, and NUA increased significantly; however, the ET, PSE, apparent nitrogen recovery (ANR), and nitrogen harvest index (NHI) decreased significantly. Furthermore, the differences between N144 and N180 in terms of the photosynthetic characteristics of wheat, the utilization of water and nitrogen, and yield were not significant. Overall, straw retention with N144 could be recommended as a resource-saving and environment-friendly management practice in a rain-fed winter wheat–fallow cropping system in northwest China.

Residue recycling options and their implications for sustainable nitrogen management in rice–wheat agroecosystems

BackgroundIn the Indo-Gangetic Plain, rice–wheat is the most extensively practiced crop rotation. The escalating issue of crop residue burning, particularly rice straw, and the necessity to lower the exorbitant expenses associated with fertilizer inputs stand out as significant challenges for farmers in the region. A well-suited integrated nutrient management (INM) strategy that focuses on recycling crop residues can serve as a solution to address these issues. Such a strategy not only mitigates air pollution resulting from residue burning but also helps combat water pollution due to nitrate losses from agroecosystems. Field experiments were used to evaluate the suitability of eight INM-modules that included various combinations of inorganic fertilizer rates (50%, 100%, 150% of recommended dose), crop residues (wheat and rice stubble retention at 30 cm standing stubble equivalent to 1/3 the straw yield), rice straw compost (RSC), farmyard manure (FYM), and green manuring (GM), compared to 100% recommended dose of fertilizers (F) and no fertilizer application.ResultsThere was a considerable improvement in nitrogen mineralization, grain yields, and nitrogen use efficiency under GM + RSC-F50 and GM + FYM-F50. These INM modules would permit a 50% reduction in the use of chemical fertilizers. There was a little yield penalty with in situ rice residue incorporation at 100% F; however, this could be overcome with 150% F fertilizer application. In situ retention of wheat straw with a full application of fertilizer resulted in steadily rising crop yields over time. Changes in the redox potential, soil pH, and soil organic carbon best accounted for the observed trajectories in nitrogen use efficiency.ConclusionThe most promising INM modules for adoption by farmers in the Indo-Gangetic Plain to judiciously use crop residues and curtail chemical fertilizer inputs are green manuring with Sesbania aculeata + rice straw compost at 5 t ha−1 + only 50% of recommended dose of fertilizers (GM + RSC-F50), and green manuring with Sesbania aculeata + farmyard manure at 5 t ha−1 + only 50% of recommended dose of fertilizers (GM + FYM-F50). Sole incorporation of crop residues without nitrogen augmentation from other sources might not help curtail chemical fertilizer use. Composting rice straw, which otherwise is widely burnt, proved a useful nitrogen source and a vital component of INM. Waste rice straw composting at the community scale and its application as a nutrient source can help achieve sustainable nitrogen management in the agroecosystems of Indo-Gangetic Plain.

Strategies to improve soil health by optimizing the plant–soil–microbe–anthropogenic activity nexus

Since the Green Revolution, world agriculture has relied heavily on agrochemical inputs (synthetic fertilizers and pesticides) in cereal- and oilseed-dominated monoculture systems, which has had long-lasting effects on soil health. Significant efforts have been undertaken to suppress these adverse impacts and resolve the conflict between producing sufficient agri-food to address world hunger and maintaining/enhancing soil health for the long run. In the context of agricultural land use and crop/soil managements impacting soil health, this comprehensive review explores the differences in soil fertility, soil quality, and soil health via delving into the complex assemblage of organisms – the home of the multi-dimensional interactive ecosystem. Through analyzing numerous studies across the major agricultural regions in the world, we provide feasible strategies to improve soil health, such as promoting the conversion of atmospheric N2 to plant-available N to enrich soil nutrients; diversifying crop rotations using alternative, cover, and green crops to increase systems’ resilience; adopting no-till with straw retention and organic/inorganic mulches to increase infiltration, stimulate enzyme activities, and enhance soil microbiome functions; and promoting C–N–water cycling to nourish soil microenvironments. These strategies, through coordinated management of the interactive nexus of plant–soil–microbe–anthropogenic activities, will help improve soil health.

Crop residue retention increases greenhouse gas emissions but reduces chemical fertilizer requirement in a vegetable-rice rotation

Retaining crop residues on site after harvesting can maintain soil fertility, reduce fertilizer requirements and restore soil organic carbon on intensively cultivated land. However, how crop residue retention and reduced chemical fertilizer application affect greenhouse gas emissions and crop yield in vegetable-rice rotations is poorly understood. We studied the effect of chemical fertilizer application alone (control, without straw retention), straw retention with 100 % nitrogen fertilizer application (STF) or with three levels of reduced chemical fertilizer application (SFR1, SFR2 and SFR3) in a vegetable-rice rotation in a mesocosm system. In the vegetable season, crop yield was maintained but the agronomic efficiency (AE) was higher in SFR1, SFR2 and SFR3 as compared to STF and the control. In the rice season under flooded condition, the methanogens were higher in SFR1, SFR2 and SFR3 compared to the control, but not different between STF and SFR1. The STF showed higher methane and nitrous oxide emissions, but carbon dioxide emissions and AE remained unaffected compared to the control in the vegetable-rice rotation. The SFR2 and SFR3 treatments maintained crop yields, increased AE, and decreased N2O emissions as compared with STF, but the CH4 emissions were 29.8 % lower in SFR2 than SFR3 in the vegetable-rice rotation. We concluded that straw retention with reduced chemical fertilizer application can maintain crop yield in a vegetable-rice rotation but has the potential to increase CH4 emissions in the rice cultivation season.

Effects of different tillage management on the growth and yield of maize (Zea mays l.)

Effects of different tillage management on the growth and yield of maize were studied from early June to September 2017. The experiment was set up with three tillage treatments: traditional shallow moldboard plow tillage with straw removal (MT), sub-soiling/ plow tillage /sub-soiling rotation with straw mulch (ST) and no-till/sub-soiling/no-till rotation with straw retention (NT). The soil compaction of different soil layers, plant height, chlorophyll content, above-ground biomass and yield were determined through the three tillage practices. Results showed that NT and ST treatments helped to reduce soil compaction, and had a positive effect on maize root growth and development, plant height and chlorophyll content compared to the MT treatment. The chlorophyll value in early growth period under NT and ST increased by 31.8 and 24.6%, respectively, and the plant height was increased by 20.2 and 15.9% compared with MT, respectively. The size order of soil compaction was MT > NT > ST, and the soil compaction value was the maximum at 20 cm under MT treatment, which was 1007 kPa. Meanwhile, NT and ST also increased the plant above-ground biomass and yield of maize. Compared to MT treatment, the dry weight of plants for the NT and ST treatments significantly increased by 24.3 and 15.7%, respectively, and the grain yield significantly increased by 11.9 and 14.9%, respectively (P < 0.05). NT and ST tillage treatments are effective measures to improve structure of soil, contribute to plant growth and development and thereby increase in yield. Bangladesh J. Bot. 52(2): 451-458, 2023 (June) Special