Straw Incorporation Research Articles

Effects of alternate wetting and drying irrigation on yield, water-saving, and emission reduction in rice fields: A global meta-analysis

With limited natural resources and uncertain climate, increasing food production must mitigate the environmental impacts. Rice, a water-intensive grain crop, contributes significantly to greenhouse gas (GHG) emissions in agricultural systems. Alternate Wetting and Drying (AWD) Irrigation stands out as the prevailing water-saving irrigation technique in rice fields worldwide. Nonetheless, the effects of AWD on yield variation, water conservation, and emissions reduction as well as the synergies and trade-offs between the effects remain unclear. Here a global meta-analysis of 437 literature sources covering 93 % of global rice production was conducted to quantify changes in yield, water utilization, and GHG emissions following AWD implementation. Results show that, on a global scale, AWD reduces irrigation water usage by 33.88 % and enhances water use efficiency, irrigation water use efficiency, and water productivity by 20.27 %, 47.58 %, and 29.63 %, respectively. However, there is a minor decrease in yield by 1.56 %. Notably, AWD leads to a noteworthy 47.47 % reduction in methane emissions, counterbalanced by a 52.20 % rise in N2O emissions, ultimately resulting in a decrease in global warming potential (GWP) and greenhouse gas intensity (GHGI) by 39.38 % and 38.06 %, respectively. The AWD threshold is the most significant predictive factor, adopting a suitable threshold can greatly improve the accuracy of AWD implementation. Soil properties also play a pivotal role, with pH levels > 7 or soil organic carbon (SOC) < 12 g/kg correlating to more pronounced yield losses. Implementing reasonable field management measures, such as suitable rice varieties and straw incorporation can effectively increase rice productivity. Approximately 60.36 % of the data falls within the “win–win” zone, demonstrating simultaneous in yield increases, water conservation, and emissions reduction. AWD is more suitable for acidic soils with high SOC (>12 g/kg) and a light texture. This study introduces novel insights for analyzing the synergies and trade-offs within the food–water–climate nexus.

Effect of Soil Acidification on Temperature Sensitivity of Soil Respiration

Soil pH significantly impacts microbial activity and community assembly, which in turn determines the temperature sensitivity (Q10) of soil respiration. Due to the high soil acidification in China, it is necessary to understand how soil acidification impacts Q10. Here, the Q10 of soil respiration was examined in a long-term field experiment (1982–present) with different soil pH caused by fertilization management. In this experiment, we selected treatments with neutral pH: (1) no crops and fertilization (CK); (2) crops without fertilization (NF); low pH with (3) crops with chemical fertilization (NPK); and (4) crops with chemical fertilization combined with wheat straw incorporation (WS). Under natural soil temperature changes, we observed that soil acidification lowered the Q10 value of soil respiration. Considering only temperature changes, the Q10 of soil respiration was strongly associated with microbial community composition, alpha diversity, and soil ammonium nitrogen. Considering the interaction between soil pH and temperature, warming strengthened the negative effect of soil pH on the Q10 of soil respiration, and the pathway through which soil pH mediated Q10 included not only microbial community composition, alpha diversity, and biomass but also the soil’s available phosphorus. This work enhanced our insights into the relationships between Q10, temperature, and soil pH by identifying important microbial properties and key soil environmental factors.

Zinc uptake in rice (Oryza sativa)-wheat (Triticum aestivum) cropping system under the influence of microbial consortia (Pusa decomposer) mediatedin situ rice straw management options

A field experiment was conducted during the rainy (kharif) and winter (rabi) seasons of 2019–20 and 2020–21 at research farm of ICAR-Indian Agricultural Research Institute, New Delhi to study the effect of various crop establishment methods and microbial consortia (Pusa decomposer) mediated in situ rice straw management options on zinc (Zn) concentration and uptake in rice (Oryza sativa L.) (cv. Pusa Basmati 1509) and wheat (Triticum aestivum L.) (cv. HD 2967). The experiment was laid out in split-plot design (SPD) with 3 replications having 2 main plot (main factor) treatments, viz. aerobic rice (AR); and conventional transplanted (CT) rice in wet season; and 7 sub- plot (sub-factor) treatments, viz. Clean cultivation (removal of paddy straw); Paddy straw incorporation (PSI); Paddy straw mulching (PSM); PSI + Pusa decomposer (PD); PSM + PD; PSI + urea @20 kg/ha; and PSI + PD + urea @10 kg/ha in dry season. Findings showed that, in rice the zinc concentration (18.51 and 20.30 mg/kg in grain; 57.02 and 57.81 mg/kg in straw) and uptake (78.38 and 89.81 g/ha in grain; 427.1 and 434.6 g/ha in straw) were significantly superior in CT rice than AR in main plots during both the years of experiments. However, sub-plot treatments were non-significant in the zinc concentration and uptake. In wheat, among in situ rice straw management options (sub- plots), paddy straw incorporation + Pusa decomposer + Urea @10 kg/ha treatment significantly resulted in higher Zn concentration (38.08 and 39.03 mg/kg in grain; 28.24 and 29.01 mg/kg in straw) and uptake (185.0 and 191.9 g/ha in grain; 234.2 and 242.6 g/ha in straw) compared to other treatments and control (clean cultivation). The principal component analysis revealed that Zn uptake positively correlated with straw and grain yields in rice and wheat. Thus, the same treatment was found to be a better option for higher Zn concentration and uptake in the rice-wheat cropping system.

Long-Term Straw Incorporation under Controlled Irrigation Improves Soil Quality of Paddy Field and Rice Yield in Northeast China.

Soil quality is an indicator of the ability to ensure ecological security and sustainable soil usage. The effects of long-term straw incorporation and different irrigation regimes on the yield and soil quality of paddy fields in cold regions remain unclear. This study established four treatments: controlled irrigation + continuous straw incorporation for 3 years (C3), controlled irrigation + continuous straw incorporation for 7 years (C7), flooded irrigation + continuous straw incorporation for 3 years (F3), and flooded irrigation + continuous straw incorporation for 7 years (F7). Analysis was conducted on the impact of various irrigation regimes and straw incorporation years on the physicochemical characteristics and quality of the soil. The soil quality index (SQI) for rice fields was computed using separate datasets for each treatment. The soil nitrate nitrogen, available phosphorus, soil organic carbon, and soil organic matter contents of the C7 were 93.51%, 5.80%, 8.90%, and 8.26% higher compared to C3, respectively. In addition, the yield of the C7 treatment was 5.18%, 4.89%, and 10.32% higher than those of F3, C3, and F7, respectively. The validity of the minimum data set (MDS) was verified by correlation, Ef and ER, which indicated that the MDS of all treatments were able to provide a valid evaluation of soil quality. The MDS based SQI of C7 was 11.05%, 11.97%, and 27.71% higher than that of F3, C3, and F7, respectively. Overall, long-term straw incorporation combined with controlled irrigation increases yield and soil quality in paddy fields in cold regions. This study provides a thorough assessment of soil quality concerning irrigation regimes and straw incorporation years to preserve food security and the sustainability of agricultural output. Additionally, it offers a basis for soil quality diagnosis of paddy fields in the Northeast China.

Analysis of Tobacco Straw Return to the Field to Improve the Chemical, Physical, and Biological Soil Properties and Rice Yield

Straw incorporation into soil contributes significantly to the sustainable development of agriculture. To investigate the impact of tobacco straw returns on a tobacco–rice replanting system, we designed an experiment with two straw return levels and a control group: T1 (full return), T2 (root return), and CK (no straw return). Over a three-year field experiment in rice fields in South China, we assessed the effects of tobacco straw return on soil quality, microbial diversity, dry matter accumulation, and yield composition of rice. The results demonstrated that returning tobacco straw to the field effectively enhanced rice yield by positively influencing various soil physical, chemical, and biological properties. Compared to those in the CK treatment, as the soil porosity increased from 9.0% to 12.4%, the mean weight diameter of the soil aggregates substantially increased, ranging from 28.7% to 45.2%. There were significant increases in soil organic matter, total nitrogen, and alkaline dissolved nitrogen. Soil sucrase activity increased between 29.8% and 44.9%, and urease activity increased between 4.3% and 62.2% over the three consecutive years of straw return. The diversity index of soil fungi significantly increased. Additionally, rice yield increased markedly, ranging from 1.8% to 5.1%. Overall, the enhancement effect of T1 surpassed that of T2. According to our comprehensive analysis, the incorporation of tobacco straw into the field was found to enhance the physical properties of the soil, elevate soil enzyme activity, and increase the abundance of soil microorganisms. Consequently, this practice led to improved rice yield and a reduction in agricultural waste output. Overall, the return of tobacco straw to the field represents a clean and dependable approach in rice-cultivated tobacco areas to improve soil health and rice productivity.

Elevated [CO2] reduces CH4 emissions from rice paddies under in situ straw incorporation

Rice paddies contribute to ∼48% of greenhouse gas emissions from cropland, with ∼94% from methane (CH4). Elevated atmospheric CO2 concentrations (eCO2) due to human activities, generally stimulate the rice growth, and in turn affect CH4 emissions from rice paddies. However, the effects of eCO2 on CH4 emissions from rice paddies are still unclear under in situ straw incorporation, the popular agricultural practice. Therefore, we conducted a 3-yr field experiment to investigate the effects of eCO2 on CH4 emissions under in situ straw incorporation in the rice-wheat cropping system, using the open-top chamber technology. We found that eCO2 reduced the CH4 emissions from rice paddies by 10.9–23.8%, but increased rice plant biomass by 4.2–35.6%. The eCO2 reduced the soil NH4+ and NO3- concentrations, but did not affect the soil dissolved organic C. The eCO2 did not affect the abundance of methanogens and CH4 production potential, whereas it stimulated the abundance of methanotrophs and CH4 oxidation potential by 102.5% and 15.1%, respectively. The eCO2 also shifted the community composition of methanotrophs and reduced the relative abundance of type Ⅱ methanotrophs by 8.5%. The random forest analysis identified that soil CH4 oxidation potential is the most important factor affecting CH4 emissions. Our findings indicate that eCO2 can reduce the CH4 emissions from rice paddies under in situ straw incorporation mainly through increasing the soil CH4 oxidation potential. Our study suggests the effects of eCO2 on CH4 emissions from global paddies may be overestimated and underline the need for smart agricultural management to reduce CH4 emissions.

Smartphone-based straw incorporation: An improved convolutional neural network

In conservation tillage, the effective incorporation of straw into soil is a critical factor for optimizing decomposition rates and addressing challenges related to straw accumulation. Consequently, this study introduces an innovative straw semantic segmentation model to extract straw mixed with soil from images, and proposes a method to measure the quality of straw and soil mixing based on this model. We conducted field experiments based on this method, analyzed the quality of straw incorporation at different depths, and finally integrated the model into a mobile application to facilitate the automatic, accurate, and rapid assessment of the quality of straw and soil mixing. The methodology of this study as an improved convolutional neural network entailed the fusion of deep separable convolution with a multi-scale feature extraction module, utilizing convolution kernels of varying sizes to capture the diverse features of straw. Further refinement included halving the first convolution channel and implementing a direct connection structure. Attention gates were strategically deployed to enhance salient features, resulting in superior accuracy compared to the original U-shaped network, fully convolutional network, and Otsu algorithm. Notably, the proposed model achieved enhanced performance while reducing the number of parameters and model complexity to one-third and one-half of the original U-shaped network, respectively. For a quantitative description of the rate and uniformity of straw incorporation, this study employed image processing technology and a grid counting method. The synergistic integration of smartphone imagery and deep learning expedited the delivery of rapid and reliable results, promising practical applicability in future straw incorporation practices. A demonstration video of the application is accessible at: https://doi.org/10.6084/m9.figshare.14480745.v3. The findings of this research contribute significantly to the advancement of conservation tillage by establishing a robust framework for the assessment and enhancement of straw incorporation operations’ efficiency.

Assessing paddy methane emissions through the identification of rice and winter crop areas using Sentinel-2 imagery in Korea

The global efforts on reducing methane (CH4) emissions was emphasized in COP 28 and the potential for improved estimation became feasible through bottom-up data acquisition with advanced remote sensing technology. The objectives of this study were to extract summer rice and winter crop cultivation areas based on satellite images and to incorporate into estimating CH4 emissions in South Korea for the year 2020. Satellite images of Sentinel-1 and Sentinel-2 were acquired from European Space Agency. Rice paddy was classified with backscattering coefficient from Sentinel-1 images, while the normalized difference vegetation index from Sentinel-2 images was used to identify winter cropping field. The equation of IPCC guidelines was used to estimate CH4 emissions by incorporating the areas of rice paddy and winter crop extracted with the respective satellite image. National farming statistics were used to determine the scaling factors for paddy organic matter and water management practices. The estimated areas for rice paddy and winter crop cultivation were 712,237 ha and 117,840 ha, respectively. The rice paddy areas were primarily concentrated in the western regions of the Korean peninsula, whereas winter crop cultivation was predominantly found in southern part of the country. The total amount of CH4 emissions was 6272 Gg CO2 eq./yr when considering rice straw and winter cropping practices into estimation (modified Tier 2 method). This represents a 7% increase compared to the method that considered solely the rice straw incorporation (current Tier 2 method). The CH4 emissions per unit area were also 8.82 tons CO2 eq./ha/yr with the modified Tier 2 method, indicating a 10% greater compared to the current Tier 2 method. Substantial CH4 emissions were primarily concentrated in western regions where extensive rice paddy cultivation occurs, while greater CH4 emissions per unit area were predominantly found in southern regions with substantial winter crop cultivation. The study findings hold importance for improving the accuracy of CH4 emissions estimation by employing bottom-up approach that utilizes satellite imagery to assess rice paddy and winter cropping areas. Further study would be needed to incorporate field-based data on rice crop management practices, such as rice straw and water management, to further refine CH4 emission estimation method.

Effect of Kharif Paddy Straw Management Options on Nitrogen Requirement to Rabi Paddy

A study conducted during the rabi season of 2020-21 at the Regional Agricultural Research Station, Polasa, Jagtial, under the auspices of Professor Jayashankar Telangana State Agricultural University, yielded insightful findings. The investigation revealed that incorporating paddy straw with a C:N ratio of 71:1 led to the immobilization of soil mineral nitrogen. Specifically, during 7, 15, and 30 days after treatment (DAT), approximately 7.2, 9.3, and 7.03 kg ha-1 of available nitrogen respectively was immobilized without phosphorus, whereas with phosphorus addition, the figures rose to 10.94, 14.75, and 11.04 kg ha-1 during the same time frames. Notably, after harvest of rabi rice significantly higher soil available nitrogen levels were recorded under paddy straw incorporation with phosphorus (169.7 kg ha-1), followed by incorporation without phosphorus (161.2 kg ha-1), and paddy straw burning (151.9 kg ha-1). Moreover, the application of nitrogen at graded levels impacted soil available nitrogen. Based on these findings, it was recommended, to counteract the immobilization effect and maximize crop yield, it was advised to apply 15% excess of recommended dose of nitrogen (RDN), as basal application.

Straw management adopted by large farms sustains grain yield but mitigates greenhouse gas emissions

ContextStraw incorporation is a globally recommended strategy for enhancing soil fertility. The methods for straw incorporation adopted by large farms usually differ from those used by small households, primarily because of variations in cost affordability. However, the effects of straw management on rice yields and greenhouse gas (GHG) emissions have not been well explored at different farming scales. ObjectivesThis study aims to compare the grain yield and greenhouse gas emissions under different straw management adopted by large farms than small households. MethodsA three-year field experiment using split-plot design, with straw management as the main plot and preceding tillage as the sub-plot, was conducted in a wheat-rice rotation system. Four treatments were given as rotary tillage with straw removal (RT-S), rotary tillage with straw incorporation (RT+S; small households), ploughing tillage with straw removal (PT-S), and ploughing tillage with straw incorporation (PT+S, large farms) in the preceding wheat season. Soil tillage in the rice season was the same, which was rotary tillage after irrigation. ResultsStraw incorporation significantly increased methane (CH4) and nitrous oxide (N2O) emissions, and 60%-62% of CH4 was emitted during the transplanting to jointing stages while 45–73% of N2O was emitted during the jointing to the booting stage. The stimulation of CH4 and N2O emissions by straw incorporation was closely correlated to enhanced soil organic carbon (SOC) and denitrification enzyme activity, respectively. In the last year, PT+S significantly reduced the global warming potential (GWP) compared to RT+S in the whole rice season, which can be attributed to the dramatically decline of CH4 emission, even though N2O emission was increased. Additionally, the decreased CH4 emission was mainly due to lower methanogenic activity, and the increased N2O emission was mainly resulted from lower nosZ abundance under PT+S compared to RT+S. Straw incorporation increased rice yield by 15.73% on average in the last two years, and rice yield of PT+S in the last year was significantly enhanced by 27.50%, resulting in a lower greenhouse gas intensity (GHGI) by 25.54% compared to RT+S. ConclusionStraw management practices adopted by large farms (PT+S) have the potential to synchronize high rice yields with lower GHG emissions compared to small households (RT+S). ImplicationsOur findings provide some evidence that large-scale agricultural organization may be helpful for sustainable rice production in China.

Long-term straw return enhanced crop yield by improving ecosystem multifunctionality and soil quality under triple rotation system: An evidence from a 15 years study

ObjectiveRice-rice-oilseed rape rotation is a typical triple cropping system in Asia, and the development of rice-oilseed rape rotation plays an important role in ensuring global food and oil security. With the intensive cropping rotation and frequent changes between paddy and upland farming under anaerobic and aerobic conditions, whether tillage and straw return would be benefit for both agronomic and environmental perspectives remained to be tested. MethodTherefore, we used a long-term locational experiment (15 years) employing four treatments of conventional tillage without straw incorporation (CT); conventional tillage with straw incorporation (CTS); no-tillage without straw mulching (NT); no-tillage with straw mulching (NTS), to assess the relationships among soil quality, ecosystem multifunctionality, and crop yields under the straw-returning and tillage strategies, based on both agronomic and environmental perspectives. ResultThe results showed that long-term straw return to the field could increase the yield of early rice by 6.24–8.80%, late rice by 3.81–7.13%, and oilseed rape by 9.55–14.45%. Long-term straw return enhanced soil quality index (SQI) by 22.21–40.74% and ecosystem multifunctionality (EMF) by 104.19–141.14% in the 0–20 cm soil layer. Long-term conventional tillage (i.e., CT and CTS) showed higher SQI and EMF values especially in the oilseed rape season. Structural equation modelling (SEM) indicated that straw return and tillage mainly increased crop yield by increasing the SQI in the oilseed rape season. ConclusionIn conclusion, long-term straw return with conventional tillage would be more benefit for the improvement of soil quality and the multifunctionality of soil ecosystems under triple paddy-upland rotation system, offering an effective approach for sustainable soil management and crop production.

Straw-derived biochar incorporation improves seedcotton yield and fiber quality by optimizing photosynthetic carbon and nutrients partitioning and boll formation patterns

Synergistic improvement of cotton (Gossypium hirsutum L.) yield and quality is necessary to meet the demands of the textile industry. Straw or biochar addition has been shown to increase boll number and hence yield, while optimizing reproductive growth processes (e.g., accelerating boll formation during the effective boll-setting period) is essential for improving fiber quality. However, it remains unclear how straw and biochar affect boll formation dynamics and whether they can simultaneously improve cotton yield and fiber quality. In order to reveal the mechanism of simultaneous improvement of cotton yield and quality, this study investigated the responses of plant photosynthetic carbon allocation, bud and boll dynamics, seedcotton yield, and fiber quality to different straw returning modes. A 7- year field experiment was performed with four straw treatments: no straw or biochar addition (CK); straw-derived biochar incorporation (SBI); straw incorporation (SI); and straw mulching (SM). The results suggested that SBI, SI and SM remarkably increased the seedcotton yield (24.5–30.7 %, 12.6–20.4 % and 4.7 %-11.0 %), fiber length (3.6–6.7 %, 4.0–9.5 % and 2.4–7.1 %) and fiber strength (8.0–13.0 %, 6.2–10.7 % and 4.4–5.7 %) from 2019 to 2021, compared with CK. There was a strong consistency between seedcotton yield and fiber strength among straw returning modes, and were highest under SBI, followed by SI and SM. Compared with CK, SBI significantly increased nutrients and photosynthetic carbon accumulation in cotton plant, and enhanced their distribution proportion in reproductive organs. This increased the number of fruiting branches, number of fruiting sites and ratio of fruiting sites to fruiting branches, accelerated budding and reduced the shedding rate of buds and bolls. Finally, SBI obtained the highest boll forming rate during the boll formation stage, as well as the highest effective boll number at the harvest stage. Overall, returning straw-derived biochar into soils optimized the allocation of nutrients and photosynthetic carbon in cotton plant, and accelerated the formation of cotton bolls from peak flowering stage to peak boll setting stage, thereby improving seedcotton yield and fiber quality. This work provides practical guidance for improving seedcotton yield, fiber quality, and the utilization of straw resources.

Enhancing Soil Aggregate Stability and Organic Carbon in Northwestern China through Straw, Biochar, and Nitrogen Supplementation

Enhancing soil stability through the incorporation of straw and biochar is well documented. Nevertheless, the combined impact of straw, biochar, and nitrogen supplementation on soil aggregates and organic carbon still needs to be explored, with limited attention given to various sieving methods in the existing literature. Therefore, the current experiment used four sieving methods—routine wet sieving (RoutW), fast-wetting sieving (FastW), slow-wetting sieving (SlowW), and wetting–stirring sieving (WetS)—to investigate the effects of adding straw (0 or 4.5 t ha−1), biochar (from maize straw, 0 or 15 t ha−1), and N (0 or 100 kg ha−1) on soil aggregate stability and soil organic C in silt–loam soil of rainfed farmland in northwest China. The field experiment was started in 2014; soil samples were collected in 2021. The results revealed that straw returned, biochar, and N addition significantly increased soil mean weight diameter (MWD) and soil organic C (SOC). Compared to CN0 (zero-amendment) plots, straw returned with nitrogen addition (SN100) significantly increased the MWD of aggregates by 130.3% (RoutW), 121.66% (FastW), 73.94% (SlowW), and 91.78% (WetS) in the 0–30 cm soil layer. The addition of biochar and nitrogen (BN100) treatment showed the most significant effects on the relative slaking index (RSI), relative mechanical breakdown index (RMI), and SOC; compared with CN0 treatment, BN100 plots can reduce RSI and RMI by 42.90% and 54.66% and increase SOC by 53.27% for all soil layers. Therefore, adding organic materials with N can enhance the stability of soil aggregates and SOC of silt–loam soils in northwest China. Integrating biochar as an organic soil amendment in the agricultural practices of northwest China presents a multifaceted solution that addresses soil health, crop productivity, and environmental sustainability. The current study provides valuable insights that support adopting this innovative approach, paving the way for future sustainable agricultural practices that can benefit both the region and the global community.

Optimizing agricultural management in China for soil greenhouse gas emissions and yield balance: A regional heterogeneity perspective

Balancing soil greenhouse gas emissions (SGE) with crop production is crucial for sustainable agriculture in China. Optimizing field management practices regionally can effectively promote carbon reduction and food security, given the varying SGE responses across agroecological regions. This study employed meta-analysis and machine learning techniques to assess SGE responses to nine different farming practices in seven distinct agroecological regions. It aimed to identify optimal management strategies for balancing SGE and crop production within each region. Findings underscore substantial spatial heterogeneity in the effects of management practices on SGE, with the combined use of organic and inorganic fertilizers (MOF-MF) demonstrating the most pronounced variability (standard deviation, SD = 1.80), where MOF resulted in SGE 610% of that with MF in the Southern China (SC) region, yet only 54% in Northwestern China (NWC). Conversely, straw incorporation exhibited the most minor variability (SD = 0.27), influencing SGE by 35%–62%. Additionally, the study reveals that soil and climatic conditions significantly modulate SGE responses. In scenarios characterized by humid and warm climates with soil pH ranging from 5.5 to 8.5 or initial SOC ≤10, the environmental impact on SGE was marginal. However, in highly acidic or alkaline soils or with initial SOC >10, SGE responses varied markedly with management practices in arid and cold conditions. The study further proposes agricultural management strategies to achieve the lowest SGE while maximizing crop yield. It recommends specific methods for fertilizer applications, straw management, irrigation, and tillage practices meticulously tailored to the unique conditions of each agroecological region. This research offers essential insights for agricultural stakeholders regarding cultivation strategies and delivers theoretical guidance for enhancing agricultural management and land-use planning throughout China's heterogeneous landscapes.

Optimization of nitrogen management reduce nitrogen stress and enhance productivity of super-seeder sown wheat under rice residue incorporation

The in-situ management of rice straw incorporation has become an essential practice in the rice–wheat cropping system with the growing adoption of super-seeder among farmers. While this equipment facilitates straw incorporation, nutrient immobilization from organic residues during decomposition poses a challenge to production. This study investigates the effect of bio-decomposer, nitrogen (N) level, and N scheduling on on various parameters in super-seeder sown wheat over two consecutive years (2020–21 and 2021–22). The experiment was laid in split-split-plot design without (B0) and with (B1) bio-decomposer, two nitrogen levels 150 (N1) and 180 (N2) kg ha−1 and three N splits (%) viz., 50: 25:25 (S1), 40: 30: 30 (S2), and 30:35:35 (S3) and replicated thrice. Results indicate significantly higher N concentration and uptake at pre- and post-anthesis with N2 and S1 compared to N1, S2, and S3. Post-anthesis N accumulation (post-NA) and remobilization (NR) were notably higher with N2. Dry matter accumulation (DMA) at anthesis and harvest significantly increased with N2 and S1 compared to N1 and S3, leading to significantly improved grain yield by 8.3% and 10.9% (two years mean). Soil urease activity (UA) significantly increased with bio-decomposer, N2, and S1 compared to B0, N1, and S3 at 30 and 60 DAS. Moreover, bio-decomposer enhanced soil microbial biomass carbon (SMBC). These findings underscore the importance of higher N levels with a greater basal N proportion in mitigating N stress and promoting sustainable wheat productivity. It also highlight the significance of effectively utilizing and conserving rice residue in the rice–wheat system.

Effect of Different kharif Paddy Straw Management Options and Nitrogen Levels on Soil Organic Carbon and Soil Total Carbon and Nitrogen

A field experiment was conducted during rabi 2020-21, at Regional Agricultural Research Station, Polasa, Jagtial, PJTSAU to study the effect of paddy straw burning and incorporation on soil organic carbon, total carbon and nitrogen and soil C:N ratio. The results of the investigation reported that incorporation of paddy straw whose C:N ratio was 71:1 showed that soil organic carbon was significantly higher under paddy straw incorporated treatments. Total carbon content of soil in paddy straw burnt treatments was 1.07 times higher than initial and in paddy straw incorporated treatments 1.51 times higher over initial was observed. Soil total nitrogen decreased with crop duration. At harvest soil total nitrogen was 2606 kg ha-1, 2693 kg ha-1 and 1931 kg ha-1 in paddy straw burning, paddy straw incorporation without phosphorus, paddy straw incorporation with phosphorus respectively. C:N ratio of soil is not influenced by paddy straw management options, nitrogen levels and the interaction between them.

Minor straw return enhances net income in a maize-wheat rotation system

Straw returning to the field is a common agricultural practice in China. Nevertheless, in the maize-wheat rotation system of the semi-arid region in Northwest China, it is essential to investigate the optimal approach for coupling straw return and fertilization in order to enhance soil quality and crop yield. A field trial conducted in the semi-arid region of northwest China from 2019 to 2021 examined eight different combinations of straw return and fertilization rates. The results indicated that while straw return had minimal impact on soil total nitrogen in the 0–60 cm layer, it did increase soil available phosphorus and potassium in the 0–40 cm layer. Additionally, all straw return treatments notably improved soil organic matter and humus content compared to the untreated control (CK). Specifically, applying N and P fertilizers in combination with returning 1/3 of the straw (NP+1/3S) produced in that season significantly boosted soil organic matter and humus content compared to the CK. Moreover, the NP+1/3S treatment led to a substantial enhancement in the grain yield of wheat and maize, as well as their yield components, including an increase in the number of ears/spikes per square meter, the number of grains per ear/spike, and the 100 or 1000-grain weight. The results may be attributed to a combination of factors, including improved nutrient availability, enhanced soil structure, and increased microbial activity due to the incorporation of straw. Economic analysis showed that NP+1/3S had the highest production to investment ratio (ROI), indicating its potential suitability for the region. This study highlights the significance of carefully selecting combinations of straw return and fertilization to maximize soil fertility, crop yield, and economic benefits in agricultural systems.

Impact of Paddy Straw Incorporation along with Different Fertilizer Doses on Mineral N Dynamics and GHG Emissions

Aim: An incubation experiment was conducted, which aimed to investigate NH4+ and NO3- release pattern and GHG emissions as influenced by paddy residue decomposition over 120 days. Study Design: Completely randomized block design. Place and Duration of Study: The study was conducted at Agrometerology laboratory, CRIDA, Hyderabad. The experiment was conducted between 2021-22. Methodology: Sampling was performed at 2, 4, 6, 8, 10, 20, 30, 45, 60, 75, 90, 105 and 120 days after incubation (DAI). The treatments included control (T1), soil + N (T2), paddy residue + 100% RDN (Recommended dose of Nitrogen) - 33:33:33 (T3), paddy residue + 100% RDN - 43:23:33 (T4), paddy residue + 100% RDN - 43:33:23 (T5), paddy residue + 10% extra RDN - 43:23:33 (T6). Fertilizer N was applied in three splits (first at initiation of experiment, second and third at 30 and 60 DAI respectively). RDN used in the study was 240 kg ha-1 (i.e., maize). Results: Residue incorporation along with inorganic fertilizer significantly influenced NH4+ - N and NO3- - N, as well as GHG emissions. After addition of each split, there was an increase in NH4+ - N and NO3- - N contents. Significantly higher NH4+ - N and NO3- - N was recorded in T6, compared to other treatments. The cumulative CO2 and N2O emissions were significantly higher in paddy residue + 10 % extra RDN – 43:23:33 i.e., 296.63 µg C g-1 of soil and 1.81 µg N g-1 of soil respectively, while lowest (42.59 µg C g-1 of soil and 0.09 µg N g-1 of soil respectively) was observed in control.

Soil Microbial Residual Carbon Accumulation Affected by Reclamation Period and Straw Incorporation in Reclaimed Soil from Coal Mining Area

Microbial residual carbon is an important component in soil carbon pool stability. Here, we tested soils collected from the early (first year, R1), middle (10 years, R10), and long-term (30 years, R30) stages of reclamation in a coal mining area in China. Two treatments with straw materials, namely maize straw + soil (S+M) and wheat straw + soil (S+W), were used for a decomposition experiment. The glucosamine and muramic acid contents were assessed. Accumulation of microbial residual C and its contribution to soil organic carbon (SOC) were analyzed at various intervals. Straw incorporation resulted in higher amino sugar accumulation than that of the control. The amino sugar content was considerably higher in R30 than that in R10 and R1; S+M and S+W showed average increases of 15 and 4%, respectively, compared to the control after 500 days. The total microbial and fungal residual C contents under S+M and S+W treatments were substantially higher than those of the control on days 33, 55, and 218 in R30. The contributions of soil microbial residues to SOC at R1, R10, and R30 were 73.77, 71.32, and 69.64%, respectively; fungal residues contributed significantly more than bacterial residues. The total amino sugars and microbial residual C content increased with increasing reclamation period. The addition of maize straw promoted the accumulation of microbial residual C, especially in the early stages of reclamation. Therefore, the addition of maize straw improved the stability of microbial carbon sources in coal mine reclamation soils.

The trade-off between root growth redundancy and premature senescence under different straw returning modes affects boll formation and seedcotton yield

The indeterminate growth habit of cotton (Gossypium hirsutum L.) makes a coordinated rootshoot relationship critical for increasing yield, which requires comprehensive consideration of root growth redundancy and premature senescence. Although recent evidence suggests that straw management affects root growth and thus seedcotton yield, there is limited documentation on the dynamics of root physiological activity and the rootshoot relationship of cotton under different straw returning modes. The present study compared four treatments: straw removal (CK), straw mulching (SM), straw incorporation (SI), and strawderived biochar incorporation (SBI) in an 8year field experiment. The growth dynamics of roots, shoots and reproductive organs, root physiological activity and seedcotton yield were investigated. The results showed that longterm straw application significantly enhanced seedcotton yield, but the effect varied significantly with straw returning modes. The seedcotton yield increased by 30.5%, 17.8% and 1.8% under SBI, SI and SM respectively in the 8th year of straw management, compared to CK. SBI and SI significantly enhanced the biomass of cotton roots and shoots while had higher growth rate of shoots relative to roots from peak squaring stage to peak bollsetting stage. This reduced root growth redundancy and increased the boll loading and boll capacity of root system. Besides, SBI increased the root activity, soluble protein content and antioxidant enzyme activities, and reduced the root malondialdehyde content from peak bollsetting stage to boll opening stage. These resulted in the greatest increase in boll number (53.862.1%) and boll biomass (39.480.4%) at the boll opening stage under SBI compared to CK. Overall, strawderived biochar improved the boll retention capacity of cotton roots by balancing the growth redundancy and premature senescence of the root system, and was a more suitable straw returning strategy to promote boll formation and increase cotton yield.