Microbiome Reveals the Effects of Biogas Fertilizer on Soil Microbial Community Structure and Diversity in Perennial Apple Orchards

Abstract

Fruit trees are perennial crops that grow in one place for their whole lives, which leads to the deterioration of the soil as well as a decline in fruit quality and yield. Microbial diversity and community structure are important soil factors affecting stress resistance and the quality of fruit trees. Additionally, biogas fertilizer also plays an important role in improving fruit quality. Whether biogas fertilizer can improve continuous cropping barriers by affecting microbial diversity and community structure remains to be further investigated. Therefore, 7-year-old Fuji apples were used as material, and biogas fertilizer was applied continuously for three years. The results show that the contents of soil organic matter (SOM), available nitrogen (AN), available phosphorus (AP), and soil porosity (SP) increased by 0.712, 0.217, 1.089, and 0.401 after applying biogas fertilizer, respectively. The concentrations of vitamin C, titratable acid, and soluble solids also significantly increased. We also found that the relative abundance of dominant soil flora significantly increased, such as Sphingomonas (g_Sphingomonas), Chlamydomonas (g_Chlamydomonas), and Stachybotry (g_Stachybotry), while the relative abundance of inferior flora significantly decreased, such as Cryptococcus (g_Cryptococcus) and Alternaria (g_Alternaria). In summary, biogas fertilizer can improve the physicochemical properties of the soil as well as the structure and diversity of the microbial communities in rainfed orchards, resulting in higher fruit quality.