Arbuscular mycorrhizal fungal and bacterial communities in chestnut orchards under different management systems

This study investigates the effects of organic management systems (OMS) on soil microbial communities and their activities, comparing them with conventional management systems (CMS) and wild systems (WS) in chestnut orchards across the Tamba region of Japan.Soil samples were collected from four distinct locations: Wachi, Ayabe, Fukuchiyama, and Sasayama.Microbial activity was assessed by analyzing nine enzyme types, while the microbial community, including bacteria and arbuscular mycorrhizal fungi (AMF), was characterized using amplicon sequencing analysis.The results revealed that in general soils under WS exhibited the highest enzyme activities followed by the OMS and then by CMS, with special regard to invertase activity.The relative abundance data indicated that Alphaproteobacteria and Betaproteobacteria were the dominant bacterial classes in orchards under OMS and CMS, while Bacilli were more prevalent under WS.Among AMF, Claroideoglomus was notably abundant in soils under OMS in Ayabe and Wachi.The bacterial richness, here represented by the number of Operational Taxonomic Units (OTUs) and Shannon-Wiener index (SW) indicated that it was higher under OMS than under conventional management systems (CMS) in certain areas.Predicted metabolic functions highlighted greater values to those related to nitrogen cycling activity in OMS-managed soils, whereas the majority of those representing the carbon cycling was more pronounced under WS followed by the OMS.The study also identified relationships between specific enzyme activities and microbial community composition, which were influenced by OMS practices.This research provides valuable insights into the impacts of different cultivation practices on soil health, emphasizing the importance of sustainable agricultural management for maintaining soil ecosystems.