Microbial decomposer assisted in situ degradation of surface retained paddy straw

Purpose Paddy (rice) straw burning is an alarming issue all over India because of its huge volume generated every year. Combine harvesting results in generation of about 5-7 ton/hectare paddy straw residue that needs to be managed with in a small period (3 weeks) before sowing of wheat crop. Method Six microbial decomposer preparations including four commercial (C-1 to C-4) and two in house culture (Delftia, Microbial consortium) have been evaluated at four different sites of Central Plain Zone of Punjab during 2018-19 and 2019-20. The microbial formulations were sprayed on the surface retained paddy straw and straw samples were evaluated after 30 days of spray for percent decrease in lignin and C/N ratio. Result A location and decomposer specific decrease in lignin (%) and C/N ratio during paddy straw surface retention trials was observed, without any significant change in wheat yield. In control (without spray), percent decrease in lignin was in the range of 2.11 to 13.57. Whereas, with microbial sprays, it varies from 7.51 to 35.79. At Ludhiana, maximum decrease in C/N ratio was obtained by C-1 and C-2 (55%), While, at Kapurthala maximum decrease in C/N ratio was obtained by Delftia (71.25%) followed by C-3 (62.62%). Conclusion The variable trend in delignification as well as C/N ratio during surface retained paddy straw trials, highlights that with microbial decomposer application the surface retained paddy straw is not appreciably decomposed in the provided window period of 3 weeks between paddy harvesting and wheat sowing.