[Legacy Effects of Long-term Straw Returning on Straw Degradation and Microbial Communities of the Aftercrop].

Abstract

Straw incorporation can improve soil fertility and soil structure. While numerous studies have explored the immediate impacts of straw return on soil properties and crop production, the legacy effects of long-term straw return remain less understood. In this study, the straw returning soil of a continuous 15 years （SS） and non-straw returning soil （NS） were collected from Dahe Experimental Station of Hebei Academy of Agriculture and Forestry Sciences in China. The simulation experiments of subsequent straw return were carried out in pots by adding straw to the two types of soil （SS and NS）, in which the degradation rate of straw was determined using the sandbag method, the number of culturable microorganisms was counted through a dilution coating plate, and microbial communities were characterized using high-throughput sequencing. The findings revealed that compared with that in NS, SS significantly increased the degradation rate of 15 d and 30 d straw by 14.16% and 26.57%； the number of soil culturable fungi in 0-60 days by 43.10%-185.92%； and the number of cellulose-degrading bacteria by 55.12%-92.04% at 0 d, 42 d, and 56 d. Additionally, after straw returning for seven days, the bacterial ACE index, fungal ACE index, and Chao1 index in SS were lower than those in NS, indicating that the microbial community richness in SS was significantly reduced. At the phylum level of bacteria, the relative abundances of Acidobacteria, Rokubacteria, and Planctomycetes in SS increased observably, with an increase of 25.92%-45.17%. The relative abundances of the phyla of fungi such as Olpidiomycota, Zoopagomycota, and Glomeromycota increased markedly, with an increase of 12.09%-176.00%. At the genus level of bacteria, the relative abundances of uncultured_bacterium_c_Subgroup_6 and uncultured_bacterium_o_Rokubacteriales in SS increased significantly, with an increase of 28.91%-31.26%, and at the genus level of fungi, the relative abundances of Paecilomyces, Penicillium, and Moesziomyces were significantly increased by 2.98%-8.79%. Network analysis showed the SS bacterial network had a higher interaction degree and network connection, and the fungal network structure was more complex and stable than that of the NS. RDA results showed that soil microbial community composition was significantly correlated with straw degradation rate. SS showed obvious legacy effects on straw degradation, the number of soil culturable microorganisms, and population structure in a certain period, and the microbial flora of SS was more conducive to the degradation of the straws.