Effects Of Soil Microbial Under Nitrogen Deposition And Biochar Amendment In A Torreya Grandis Orchard

Atmospheric nitrogen?N?deposition significantly affected soil microbial biomass.However,whether biochar amendment can offset these effects in orchard is still unclear.Therefore,we studied the effects of these two factors on soil microbial biomass carbon?MBC?,enzyme activities and microbial diversity in Torreya grandis orchard with high-throughput sequencing method.The study showed:?1?biochar amendment significantly decreased MBC.After one year's treatment,low N depositon(30 kg ha^-1yr^-1)significantly increased MBC,but high N depositon(60 kg ha^-1yr^-1)significantly decreased MBC;interaction of N deposition and biochar significantly increased MBC,while decreased after two years.?2?Biochar amendment increased catalase and cellulase activity,low biochar(20 t ha^-1)amplified the positive effect of N deposition on catalase activity.Urease and?-fructofuranosidase activity had a positive response in interaction treatments.After two years' treatment,the activities of cellulase,nitrite reductase and urease are more than one year later under all of treatments.?3?Biochar amendment significantly influenced the Chao1 index of the bacterial and fungi,but largely intensified the negative effects of N deposition on microbial diversity?particularly fungi?.?4?Soil microbial community structures and enzyme activity were significantly related to soil pH,available phosphorus,and total N.The study provided an important reference for us to fully understand the response of soil ecosystem of Torreya grandis orchard to nitrogen deposition and biochar amendment.