Abstract
This study aimed to investigate the influence of different organic fertilizers and their concentrations on the growth of 'Orah' (Citrus reticulata Blanco) seedlings, as well as on the mineral nutrient contents, chemical and biological properties, and microbial community of the soil. Five types of organic fertilizers and three concentrations were studied. The seedling growth indexes, leaf mineral elements, soil mineral elements, soil enzyme activity, and soil microorganisms were measured. The results showed that organic fertilization significantly increased the contents of eight mineral elements in leaves, depending on the types and concentrations used. Specifically, rapeseed cake fertilizer was found to significantly increase the content of iron (Fe), manganese (Mn), and zinc (Zn) in the leaves. Furthermore, compared with applying only chemical fertilizers or no fertilizers at all, the application of organic fertilizer significantly increased the content of soil organic matter (SOM) and several mineral elements in the soil. The bacterial species composition of soil treated with common organic fertilizer and bio-organic fertilizer, and sheep manure were similar; however, the bacterial composition was significantly different in the soil which been treated with rapeseed cake compared to these other three fertilizers. Additionally, PICRUSt function predicting indicates that the core microbial community in the rapeseed cake group could promote synthesis and the transport of sugar, iron and other substances. Organic fertilizer can change soil chemical and biological properties by affecting the core microbial community structure, and further promote accumulation of mineral elements in the leaves of citrus seedlings.