not to use

Applying composts as soil amendments has a long history to sustain and improve the functionality of agricultural soil. Compost is a carrier of organic matter and microorganisms. However, few studies have manipulated these two factors simultaneously and investigated the relative effects of these two key compost components on soil microbial community and crop growth. To bridge this gap, the aim of this work is to study how soil microbial communities and wheat respond to the amendment of sterile and non-sterile composts, with three different maturities, in a soil microcosm experiment. We found that the changes in the soil microbial community were mainly due to input of compost-derived microorganisms instead of the input of organic matter. The majority of the compost-derived microorganisms survived in the soil in the presence of native soil microorganisms, and removal of native soil microorganisms promoted the prevalence of compost-derived microorganisms. Adding fresh compost increased wheat biomass production compared with the mature composts and this was related to high abundance of Sordariales fungi in fresh compost amended soil. Soil amended with sterilized compost had higher wheat biomass compared to soil amended with non-sterilized compost due to reduced nutrient competition, because sterilization suppressed nutrient cycling-related Actinomarinales, Bacteroidales and Cellvibrionales bacteria.