ABSTRACT Cover cropping with hairy vetch (HV) plays a pivotal role in shaping soil nutrient dynamics and ammonia‐oxidising microorganisms, though its effects across different crop systems are not well studied. This study investigated how HV planting affects soil physicochemical properties, potential nitrification activity (PNA), and ammonia‐oxidising microbial communities in peanut‐ and sweet potato‐growing soils. HV planting significantly increased soil organic carbon (SOC), total nitrogen (TN), ammonium (NH 4 + ), and available nitrogen (AN) in sweet potato‐growing soils but had negligible effects on these properties in peanut‐growing soils. PNA was higher in the topsoil than in subsoils, and HV planting had no significant effect in either crop system. The gene abundances of ammonia‐oxidising archaea (AOA), bacteria (AOB), and comammox Nitrospira responded differently to HV planting. In peanut soils, HV planting decreased comammox Nitrospira diversity and abundance while significantly altering community structure, mainly due to reductions in soil pH. In contrast, HV planting had limited effects on comammox Nitrospira diversity and structure in sweet potato soils but lowered AOA gene abundance in the topsoil. Across both systems, the comammox Nitrospira clade A.2 dominated the community, and soil pH was the most influential driver of community composition. These results demonstrate that HV planting induces crop‐specific effects on soil ammonia‐oxidising microorganism dynamics, providing valuable insights for sustainable agricultural management and optimising soil nitrogen processes in peanut and sweet potato systems.
Sun et al. (Tue,) studied this question.