Impact of microbial decomposers spray on in situ degradation of paddy straw stubble left in the field after paddy harvesting in Punjab

Effects of microbial decomposer application were studied relative to in situ decomposition of paddy straw in the rice-wheat system using both paddy straw incorporation (i.e. mechanical mixing of leftover straw and stubble using rotavator) and retention (i.e. leftover straw and stubble without mechanical mixing) methods. An experiment was conducted on paddy straw degradation during 2020-2021 and 2021-22 using microbial consortium (decomposer) at four locations in Punjab, India using three different treatments. Lignin content, C/N ratio, and tensile strength after 30 days of incorporation and retention of paddy straw were recorded. Microbial treatment along with incorporation improved decomposition parameters from 32.0 to 32.6% (C/N ratio) and 47.5 to 36.6% (lignin), whereas a major share – 28.6 (C/N ratio) and 36.6 (lignin) per cent of decomposition was achieved by soil incorporation as such. Wheat grain yield with and without microbial decomposer was similar across sowing methods (incorporation vs retention) in all locations. Similar observations were recorded in 2021-22 also at the same site of PAU, Ludhiana. Microbial agents responsible for the degradation of straw are present in sufficient quantity in the soil and incorporation of paddy straw in the soil by incorporation using a rotavator can enhance the paddy straw decomposition.