Effect of tillage systems and nitrogen management on the efficacy of decomposers for in-situ crop residue management in rice- wheat cropping system
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Date
2023
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Department of Agronomy, BAU, Sabour
Abstract
The Indo-Gangetic Plains' rice-wheat (RW) cropping system has contributed significantly to India's food security. However, because of declining soil health, increasing demand on natural resources, and new climate change issues, the sustainability of this significant cropping system is in jeopardy. Innovations in crop residue management to prevent straw burning should help farmers achieve sustainable production while reducing nutrient and water inputs and risk from climate change. The irrigated RW system's high yields have produced enormous amounts of crop wastes. Straw burning especially of rice is a common practice that depletes nutrients and seriously impairs air quality, endangering human health and safety. For their management, keeping rice residues as surface mulch in wheat crops is a smart choice. Mulching reduces weed pressure while increasing yield, water productivity, and profitability. Studies on recycling rice residue have been found to improve soil health and quality. Since rice residues are a key source of plant nutrients, regular application can reduce the management of fertiliser in the RW system. The present experiment was carried out during the kharif and rabi seasons of 2020 and 2021 using a split-split plot design with two tillage systems as main plot factors: T1: Puddled transplanted rice – conventional tillage wheat (PTR–CTW) and T2: Zero tillage direct seeded rice – zero tillage wheat (ZTDSR–ZTW); four nitrogen management strategies, N1: No Starter Dose of N (SD) + RDF, N2: SD (25 kg N/ha) + (RDF-25 kg N/ha), N3: SD (25 kg N/ha), and N4: SD (5 kg N/ha foliar spray) + RDF, were applied to the sub-plot and three decomposers-D1: Trichoderma, D2: Aspergillus, and D3: Pusa Decomposer were used as sub-subplot treatments. Findings from the study suggests that treatments T2 (ZTDSR-ZTW), N3 (SD (25 kg N/ha) + RDF), and D3 (Pusa decomposer), increased plant growth parameters individually in both the crops during both the year. Among the tillage systems, conventional PTR produced 2.78 % higher yields as compared to ZTDSR however, ZT wheat yields were 12.01 % higher over CTW. The rice equivalent grain yield was 4.7 % higher in ZTDSR–ZTW system as compared to PTR–CTW system. Application of N3 (SD (25 kg N/ha) + RDF) and D3 (Pusa decomposer) resulted in 11.5 % and 6.4 % higher rice equivalent yields over other treatments. Tillage (T1 in rice and T2 in wheat) along with N3 (SD (25 kg N/ha) + RDF) and D3 (Pusa decomposer) recorded significantly higher yield compared to other treatment combinations. Splitting of RDF nitrogen as starter dose and post crop application (N2) resulted in 1 % lower yield in rice and 5.7 % lower yield in wheat over RDF application (N1). The economic analysis in rice showed that puddle transplanting resulted in 9 % higher gross returns and 5.8 % higher net returns whereas, B:C ratio of ZTDSR were observed to be 3.39 % higher as compared to PTR. In wheat, gross returns (11.4 %), net returns (29.6 %) and B:C ratio (25.76 %) recorded significantly higher values in ZT over conventional tillage. It was also found that crop residue retention (ZTDSR–ZTW) significantly improved various soil properties and some important soil parameters added their benefit in enhancing the soil quality in T2 (ZTDSR–ZTW) such as particulate organic carbon, soil available nitrogen, beta-glucosidase and bulk density. Retention of crop residues significantly improved the soil quality index under T2 (0.87) as compared to (0.81) in T1 tillage system where the residues were incorporated. Among the decomposers Pusa Decomposer significantly improved the soil quality index as compared to Aspergillus or Trichoderma. On the basis of two years study conducted it may be concluded that Zero Tillage in rice may not positively impact the rice yields in short term however, ZT was beneficial for wheat and helped improve the system rice equivalent yields. Moreover, it was found that crop residue retention was less resource intensive as compared to residue incorporation and helped in improving the soil quality sustainably as compared to crop residue incorporation. Additional application of nitrogen as starter dose helped in increasing the crop yields in combination of application of decomposers. Splitting the recommended dose of fertilizer (RDF) as starter dose for residue decomposition and remaining RDF as post crop establishment negatively impacted the crop yields. Combination of appropriate tillage and nitrogen management along with application of suitable decomposers can sustainably increase the crop yields while reducing the production costs as well as improve the soil health over time.