The coupling effects of long-term straw return and plant selection facilitate rhizosphere nitrogen supply by promoting recruitment of core genera

Abstract

Straw return has been widely recommended as an effective agricultural practice for improving soil microbial community structure and nitrogen supply. Despite substantial researches on microbial changes in rhizosphere and bulk soils, the interaction between long-term straw incorporation and plant selection on rhizosphere microbial contributions to soil nitrogen supply are still not fully clear. Here, we show through an 11-year field experiment that the interaction effect of straw return and plant selection had a greater impact on bacterial community compared to the individual effects of straw return or plant selection. This interaction reduced α-diversity at the jointing and heading stages, increased community differentiation, enhanced microbial network connectance, and elevated the relative abundances of Rhizobiales, Sphingomonadales, and Xanthomonadales. Weighted Correlation Network Analysis identified core bacterial genera associated with nitrogen supply, such as Sphingomonas, Bradyrhizobium, Pseudolabrys, and Gemmatimonas. The interaction increased the relative abundance of these key genera in the rhizosphere. Furthermore, Partial least squares-path modeling analysis revealed that soil microbial communities and their associated nitrogen supply are influenced by soil dissolved organic carbon, which is regulated by the effects of straw return and plant selection. These findings offer insights into plant-microbe feedback mechanisms and informing strategies for sustainable, high-yield agriculture.