Manure substitution of chemical fertilizer affect soil microbial community diversity, structure and function in greenhouse vegetable production systems

Abstract

Soil microbial community and enzyme activities together affect various ecosystem functions of soils. Fertilization, as important agricultural management practices, are known to modify soil microbial characteristics; however, inconsistent results have been reported. The aim of this research therefore was to make a comparative study of the effects of different fertilization patterns (No N inputs (No N), 100% chemical fertilizer-N (CN) inputs (4/4CN) and different substitution rates of CN by organic manure-N (MN) (3/4CN+1/4MN, 2/4CN+2/4MN and 1/4CN+3/4MN)) on soil physicochemical properties, enzyme activities and microbial attributes in a GVP of Tianjin, China. Manure substitution of chemical fertilizer, especially at higher substitution rate (2/4CN+2/4MN and 1/4CN+3/4MN), improved soil physicochemical properties (higher soil organic C (SOC) and nutrient contents; lower bulk densities), promoted microbial growth (higher total phospholipid fatty acids and microbial biomass C contents) and activity (higher soil hydrolase activities). Manure addition caused a remarkable increase of the fungi/bacteria ratio and a distinct shift in the fungal (bacterial) community to greater abundance of arbuscular mycorrhizal fungi (G+ bacteria) compared with saprotrophic fungi (G- bacteria). These changes drove shifts toward fungal-dominated soil microbial communities and then optimized microbial community structure. Also, manure application increased soil biodiversity (microbial community and enzyme function), indicated by increased Shannon-Wiener diversity. Redundancy analysis indicated that the most possible mechanism of the impacts of different fertilization patterns on soil microbial characteristics may be the mediation of SOC and nutrient (N) availability (especially SOC) in this GVP of China. In conclusion, manure substitution of chemical fertilizer, especially at higher substitution rate, was more efficient for improving soil quality and biological functions.