Interlinkages between soil properties and keystone taxa under different tillage practices on the North China Plain

Abstract

Revealing the role of keystone taxa in maintaining community structure and driving soil properties is crucial for estimating agri-soil quality and microbial function. However, it is still unclear that how tillage practices mediated the associations between keystone taxa and soil properties to affect soil quality. Hence, this study aimed to investigate the influences of no tillage (NT), conventional tillage (CT), and plow tillage (PT) on soil microbial community structure, co-occurrence pattern, and keystone taxa, as well as the correlations between keystone taxa and soil properties. Compared with NT, CT and PT exhibited lower soil organic carbon (SOC), bulk density (BD), and mean weight diameter, as well as higher cumulative carbon mineralization (Cm). Bacterial diversity and richness were decreased under PT. A total of 58 keystone taxa were identified in the co-occurrence network and 35 genera were significantly separated by tillage practices. Most cellulolytic, chitinolytic, and nitrobacterium genera involved in decomposing complex soil organic matter were abundant under PT. Soil quality index (SQI) of the three tillage practices were in the following order: NT > CT > PT, while the Cm and SOC had greater communalities in SQI. Structural equation model (SEM) further indicated that tillage practices affected soil quality by mediating bacterial diversity and keystone taxa. Additionally, network analysis and SEM indicated that keystone taxa were significantly driven by SOC, Cm, and BD. Overall, the study findings suggested that keystone taxa might serve as biomarkers of agri-soil quality, and healthy farmland ecosystems might be obtained by targeting these species.