Impact of Residue Retention on Methane Flux in a Maize-Chickpea Cropping System in Tropical Vertisols of Central India

Abstract

A field experiment on methane cycling under different crop residue retention in a maize-chickpea cropping system was conducted during the kharif-rabi seasons (2022-2024) at the research farm of the Indian Institute of Soil Science, Bhopal (M.P.). The study aimed to evaluate methane consumption and production potential in soil under different crop residue incorporation levels and to assess the microbial communities associated with methane cycling. The experiment was designed in a RBD with five replicates, two tillage practices (conventional tillage and no-tillage), three crop residue retention levels (0%, 30%, and 90%), and two soil depths (0-15 cm and 15-30 cm). The four treatments included : T1 (0%  residue retention), T2 (30%  residue retention), T3 (90% residue retention), and T4 (conventional tillage for comparison with different residue levels). The findings from this study provided insightful information on sustainable residue management practices for improving soil health, enhancing microbial activity, and mitigating methane emissions under conservation agriculture in Vertisols of Central India. In maize crop, rates of CH4 consumption (CH4 consumed g/soil/day) varied from 2.00 to 4.49 in 0-15 cm and 0.74 to 2.06 in 15-30 cm. CH₄ consumption was higher in maize, particularly in the upper soil surface, while chickpea contributed to CH4 uptake but to a lesser extent. CH4 production rate ranged from 0.11 to 0.13 ng CH4 produced g/soil/day and 0.008 to 0.014 ng CH4 produced g/soil/day  soil in maize and chickpea. There was no significant difference among the treatments of depth. Abundance of microbial groups belonging to  methanotrophs and methanogens were estimated by real time PCR targeting genes of  methanotrophs (pmoA) and methanogens (mcr) genes. Abundance was represented as gene copies g−1 soil. Results indicated that the microbial genes were significantly highest in 90% residue retention in maize crop due to the amendment by chickpea crop residues. Overall, Organic carbon and β-glucosidase activity was slightly higher in chickpea crops compared to maize, likely due to the greater microbial support provided by legumes, which enhance soil biological activity. The study highlights that crop residues retention influences both CH4 consumption and production potential of soil and this effect is more pronounced with higher residue than conventional tillage.