Understanding the long-term impacts of different tillage regimes, crop establishment methods and residue management is critically important for sustainable agricultural management. These factors play pivotal role in shaping the dynamics of soil organic pool, enzymatic activity and bacterial diversity, which eventually influences the crop productivity of rice-wheat cropping system (RWCS). We therefore, investigated the long-term (9-years) crop performance under contrasting tillage regimes viz. conventional tillage (CT) and zero tillage (ZT) with (+ R) and without (-R) residue management in wheat, and two rice establishment methods i.e., direct seeded rice (DSR) with CT and ZT and puddled transplanted rice (PTR) in a RWCS. We investigated the impacts of nine treatments comprising three combinations each in rice (DSRZT, DSRCT and PTR) and wheat establishment (WCT−R, WZT−R and WZT+R) on crop (rice/wheat) yields, soil enzymatic properties, organic carbon (C) pool and biological properties after 9-years of RWCS. After competition of 9 cycles of continuous RWCS, crop yields were significantly (p < 0.05) higher under DSRCT/(ZT+R) and PTR + W(ZT+R) as compared to the DSRCT+W(CT−R) and PTR + W(CT−R). The DSRCT+W(ZT+R) and PTR + W(ZT+R) treatments significantly increased the water extractable organic C, basal soil respiration, microbial biomass C, total glomalin and organic C concentrations by 14.2–37.8%, 38.2–43.3%, 17.4–29.9%, 19.4–24.3% and 7.7–18.1%, respectively relative to PTR + W(CT−R). Nonetheless, under DSRCT+W(ZT+R) and PTR + W(ZT+R) treatments, the activities C, N, and P cycling related soil enzymes viz. β-glucosidase, cellulase, xylanase, laccase, L-asparaginase and alkaline phosphate were increased by 15.4–16.0%, 24.2–270%, 24.0-24.2%, 172–180%, 28.9–30.4% and 29.4–40.0%, respectively relative to PTR + W(CT−R).The W(CT/ZT+R) treatment had higher rice root biomass, leaf + stubble biomass, rhizodeposition and total C by 10.3–12.9%, 10.7–14.6%, 11.0-14.9% and 10.3–13.9%, respectively as compared to W(CT/ZT−R). The changes in soil organic C pools, biological properties and enzyme activities under DSRCT+W(CT−R) were nearly similar to PTR + WCT−R. Metagenomics analysis revealed that residue management had positive impact on soil bacterial community, diversity, and richness, which was discernible by improvements in Proteobacteria, Actinobacteria and Chloroflexi activity to enhance decomposition process. Reduced tillage intensity coupled with residue management provided a viable option for achieving sustainable development of agriculture security. These results could have a significant impact on the development of policies for efficient use of resources, while maintaining agricultural productivity.

Soil Enzymatic Activity, Bacterial Diversity and Organic Carbon Pool in Response to Residue Management and Intensive Tillage in Rice-Wheat Cropping

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发表日期：

2025年3月13日

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Sandeep Sharma,
Pritpal Singh,
Yadvinder Singh

摘要

Understanding the long-term impacts of different tillage regimes, crop establishment methods and residue management is critically important for sustainable agricultural management. These factors play pivotal role in shaping the dynamics of soil organic pool, enzymatic activity and bacterial diversity, which eventually influences the crop productivity of rice-wheat cropping system (RWCS). We therefore, investigated the long-term (9-years) crop performance under contrasting tillage regimes viz. conventional tillage (CT) and zero tillage (ZT) with (+ R) and without (-R) residue management in wheat, and two rice establishment methods i.e., direct seeded rice (DSR) with CT and ZT and puddled transplanted rice (PTR) in a RWCS. We investigated the impacts of nine treatments comprising three combinations each in rice (DSR_ZT, DSR_CT and PTR) and wheat establishment (W_CT−R, W_ZT−R and W_ZT+R) on crop (rice/wheat) yields, soil enzymatic properties, organic carbon (C) pool and biological properties after 9-years of RWCS. After competition of 9 cycles of continuous RWCS, crop yields were significantly (p < 0.05) higher under DSR_CT/(ZT+R) and PTR + W_(ZT+R) as compared to the DSR_CT+W_(CT−R) and PTR + W_(CT−R). The DSR_CT+W_(ZT+R) and PTR + W_(ZT+R) treatments significantly increased the water extractable organic C, basal soil respiration, microbial biomass C, total glomalin and organic C concentrations by 14.2–37.8%, 38.2–43.3%, 17.4–29.9%, 19.4–24.3% and 7.7–18.1%, respectively relative to PTR + W_(CT−R). Nonetheless, under DSR_CT+W_(ZT+R) and PTR + W_(ZT+R) treatments, the activities C, N, and P cycling related soil enzymes viz. β-glucosidase, cellulase, xylanase, laccase, L-asparaginase and alkaline phosphate were increased by 15.4–16.0%, 24.2–270%, 24.0-24.2%, 172–180%, 28.9–30.4% and 29.4–40.0%, respectively relative to PTR + W_(CT−R).The W_(CT/ZT+R) treatment had higher rice root biomass, leaf + stubble biomass, rhizodeposition and total C by 10.3–12.9%, 10.7–14.6%, 11.0-14.9% and 10.3–13.9%, respectively as compared to W_(CT/ZT−R). The changes in soil organic C pools, biological properties and enzyme activities under DSR_CT+W_(CT−R) were nearly similar to PTR + W_CT−R. Metagenomics analysis revealed that residue management had positive impact on soil bacterial community, diversity, and richness, which was discernible by improvements in Proteobacteria, Actinobacteria and Chloroflexi activity to enhance decomposition process. Reduced tillage intensity coupled with residue management provided a viable option for achieving sustainable development of agriculture security. These results could have a significant impact on the development of policies for efficient use of resources, while maintaining agricultural productivity.