Impact of Microbial Inoculants and Additives on Rice Straw Composting

Rice straw is a lignocellulosic waste, which is recalcitrant in nature and contains high lignin content. A recalcitrant property provides resistance from natural degradation thus, decomposition of lignocellulosic waste becomes a difficult task. Composting of rice straw is a sustainable practice that benefits environment, agriculture and economy by turning the agricultural waste into valuable resource that might otherwise be burnt or left to decompose inefficiently. This study investigated the effect of different additives on composting of rice straw with combination of microbial consortium (bacteria and fungi). The addition of organic supplements (i.e., biogas slurry, rock phosphate and green waste) significantly raised the initial temperature of compost treatments, and microbial consortium accelerated lignocellulose decomposition during composting. Organic carbon was found to decrease in all the treatments with the progression of decomposition and least i.e. 29.50% was observed in treatment T5 [rice straw + biogas slurry + rock phosphate + green waste (4:1:1:1) + microbial consortium] at the end of composting which had initial organic carbon of 44.80%. A comparative increase in nitrogen content was observed in all the treatments with the commencement of decomposition. After 90 days of composting, treatment T5 contained the highest total nitrogen (1.36%) ultimately led to decrease in C/N ratio. Among all the treatments, T5 showed noticeably increased degradation rate of cellulose, hemicellulose and lignin content. Moreover, humic acid in compost from T5 was also found to be highest (108 mg g-1). The use of additives seems to improve the stability of rice straw compost as well as use of microbial consortium was found to reduce the time of decomposition of substrates. The research findings will be helpful in optimizing the use of organic waste materials by turning them into nutrient rich compost more quickly and effectively.