Unlocking the potential of straw return: Microbial agent-driven lignocellulose degradation and soil nitrogen availability in wheat fields

Straw returning to field is considered as a sustainable way of straw utilization. In this study, a novel and effective microbial agent (MA) was applied to the straw returning soil during the winter wheat growing season. The addition of MA increased the weight loss ratio of corn straw from 6.94 % to 25.87 % after 10 days under laboratory conditions, especially for the degradation of cellulose and hemicellulose. In the field experiment, the addition of MA also accelerated the degradation of corn straw in soil, consequently increased the content of total nitrogen in soil. The soil metagenomics analysis showed that relative abundance of Nocardioides, Solirubrobacter and Arthrobacter were increased at the species level which could enhance corn straw degradation in soil. The abundances of GHs (glycoside hydrolase) and AAs (auxiliary active enzyme) family genes increased and this was likely to have promoted the degradation of corn straw. In addition, the abundances of nitrifying and denitrifying genes such as amoA-A, amoB-B, amoC-C, nxrA, narH, and narI were increased at the overwintering stage and booting stage which could improve the nitrogen cycling in soil. MA promoted the degradation of corn straw, increased the expression of nitrification and denitrification genes, However, it did not result in a statistically significant increase in wheat yield. This was an effective way to promote the sustainable development of agricultural production through functional microbial resources mining and MA application.