The more straw we deep-bury, the more soil TOC will be accumulated: when soil bacteria abundance keeps growing

Maize straw deep burying into 20–40-cm layer before covering soil and plowing ridge is a useful practice to enhance soil carbon pool and make soil bacteria rich. Now, we hope to bury much more straw to reuse the huge number of them until catching the soil environmental carrying capacity in fertility, like soil organic carbon and enzyme activities. But the reasonable straw amount to return back has not been determined. Focusing on the actual output quantity of China maize straw, we designed a 7-year-term field experiment with 4 different straw deep-burying amounts of 0 t ha–1 (CK), 6 t ha–1 (SR1), 12 t ha–1 (SR2), and 18 t ha–1 (SR3). We clarified the reaction of straw amount to soil bacterial community and enzyme activities, by soil fertility, qPCR (quantitative real-time polymerase chain reaction), and Illumina high-throughput sequencing. According to the result, using 18 t ha–1 straw got the most enzyme activities of urease, cellulase, invertase, and dehydrogenase, more than others 4.71–332.38%. The 16S rRNA gene abundance of the sample with 18 t ha–1 straw has a significant rise compared to 0 t ha–1 (32.47%) and 6 t/ha (29.52%). Three domination bacteria of Proteobacteria, Actinobacteria, and Acidobacteria were sensitive to the straw using amount, and their relative abundance increased as straw amount enhancing. The microbial diversity changes finally increased the corn yield. Therefore, the more straw we used, the more abundance soil bacteria and the soil TOC we would get, in the condition of straw amount under 18 t ha–1 by deep-burying method. So we should put much more straw into soil rather than abandonment.