Effects of biochar from different raw materials on atrazine removal and microbial community structure in farmland soil

【Objective】In order to obtain the best biochar type for atrazine removal,the effects of different biochars on atrazine removal and microbial community in farmland soil were studied,which could provide a reference for farmland soil remediation with atrazine.【Method】Biochar was prepared with cow dung,bagasse and sludge as raw materials. Atrazine degradation rate,soil p H,organic matter content,humus content,soil enzyme activities and microbial community structure were determined at 0,10,20,30 and 40 days,respectively.Redundancy analysis was used to explore the correlation between atrazine degradation rate,environmental factors and bacterial community structure. 【Result】The results showed that the addition of biochar could greatly promote atrazine degradation in soil,which performed as the atrazine degradation rate of bagasse biochar(67.94%)>cow dung biochar(58.39%)>sludge biochar(48.63%). Meanwhile,biochars application significantly increased the p H value,organic matter and humus content of soil(P<0.05,the same below),improved microbial activity and diversity of community structure,and accelerated the biodegradation of atrazine,in which the bagasse biochar had the most significant effect that increased the pH value,organic matter and humus of soil by23.76%,4.39 g/kg and 2.24 g/kg respectively than without biochar(CK). In addition,biochar application significantly increased the activities of soil dehydrogenase,catalase and urease,and promoted the abundance of atrazine-degrading microorganisms Sphingomonadaceae,Burkholderiaceae,Streptomycetaceae,Micrococcaceae and Micromonosporaceae.Redundancy analysis showed that both environmental factors and functional microorganisms contributed to the degradation of atrazine,and bagasse biochar was positively correlated with the pH,organic matter,atrazine degradation and humus.【Conclusion】Application of biochar improves soil physicochemical properties(pH,organic matter and humus),significantly increases the abundance of atrazine degrading bacteria Sphingomonadaceae,Burkholderiaceae,Streptomycetaceae,Micrococcaceae and Micromonosporaceae,and thus accelerates the removal of atrazine from soil,among which bagasse biochar has the best effect. Biochar made from waste bagasse can be used to recycle agricultural waste,repair atrazine pollution and improve soil fertility in farmland.