Abstract: Our objective was to investigate the effects of agricultural management on the structure and diversity of soil arbuscular mycorrhizal fungi (AMF) communities. An experiment was conducted in a mountainous area of south Ningxia with four treatments: no-tillage mulching without organic fertilizer application (NC), no-tillage mulching with organic fertilizer application (NF), conventional tillage without organic fertilizer application (TC), and conventional tillage with organic fertilizer application (TF). Illumina MiSeq sequencing technology was used to analyze the impacts of conservation tillage measures on the structure and diversity of soil AMF communities. The results showed that: (1) Tillage significantly affected soil available N and available K contents. Compared with no fertilization, organic fertilizer application significantly altered soil pH, available P, available K and organic matter. Soil available K and organic matter contents of NF treatment were significantly increased. (2) In all the 16 soil samples, 1 phylum, 3 classes, 4 orders, 5 families, 7 genera of AMF were identified. The dominant genera wereGlomus, Claroideoglomus, andParaglomus. Organic fertilizer application decreased the relative abundance of dominant genera. (3) Both tillage and organic fertilizer application did not affect the species richness of soil AMF. Tillage significantly affected evenness (Pielou_e) and diversity (Shannon and Simpson indices) of soil AMF. Notillage mulching without organic fertilizer application (NC) increased evenness (Pielou_e) and diversity index (Shannon index) of soil AMF. Both fertilization and tillage affected the composition of soil AMF community, with the effect of tillage on the diversity of soil AMF community being more obvious. (4) The results of nonmetric multidimensional scaling and redundancy analysis showed that total nitrogen and pH were the dominant variables affecting AMF community composition, but were not the key environmental variable driving AMF community change. Therefore, conservation agricultural management practices of no-tillage mulching and organic fertilizer application could improve soil physicochemical properties and increase soil AMF community diversity in the mountainous area of south Ningxia.

Key words: no-tillage mulching, organic fertilizer, high-throughput sequencing, arbuscular mycorrhizal fungi, diversity.