Impact of a soil sampling strategy on the spatial distribution and diversity of arbuscular mycorrhizal communities at a small scale in two winter cover crop rotational systems

It is vital to evaluate how soil sampling affects the spatial distribution and diversity of arbuscular mycorrhizal fungi (AMF) in agricultural ecosystems. Here, the impact of soil sampling on the spatial distribution and diversity of AMF in agricultural ecosystems was evaluated using field experiments. A molecular approach was taken to assess the spatial distribution of the AMF community from 1 m2 plots from fields cropped with soybeans [Glycine max (L.) Merr.], in rotation with wheat (Triticum aestivum L.) and winter fallow. Phylogenetic analysis revealed 18 AMF phylotypes, including five Glomus, three Gigaspora, two each from Racocetra, Acaulospora, and Funneliformis and one each from Claroideoglomus, Rhizophagus, Diversispora, and Paraglomus at different sampling points in this study. Our results showed that the molecular diversity and composition of AMF communities in soil cropped with wheat, or left fallow did not change at scales of < 1 m2. Canonical correspondence analysis (CCA) demonstrated that AMF communities by soil sampling point within each rotation were not significantly different. Thus, random soil sampling did not show any difference in AMF communities in soil under winter cover crop rotational systems, no matter where soil samples were collected from at a small scale (< 1 m2) in agricultural fields. Our results suggest that agricultural management can affect the diversity and composition of AMF communities more than soil sampling strategies.