Silkworm excrement (SE) and silkworm excrement-derived biochar (BC) were applied to atrazine-contaminated soil at the rates of 0% and 0.5% (w/w), respectively. The effect of organic amendments on sorption capacity, microbial biomass carbon, enzyme activity (dehydrogenase, urease and catalase) and bacterial composition in soil were evaluated. Atrazine significantly decreased the microbial activity and diversity in soil. Both SE and BC treatments increased the sorption of atrazine in soil. SE treatment significantly increased the microbial biomass carbon and enzyme activity in contaminated soil. Unlike the addition of silkworm excrement, BC treatment had no significant effect on dehydrogenase activity. Additionally, Illumina-MiSeq sequencing analyses showed that the two organic amendments increased the Shannon index of bacteria. SE treatment improved the relative abundance of Bacteroidetes. BC treatment improved the Proteobacteria in atrazine contaminated soil.
