Effect of Applying Spent Mushroom Culture Residues to Tea Garden on Soil Organic Carbon Content and Humus Composition

Based on the field survey and laboratory analysis,the effect of applying spent mushroom culture residues to tea garden was investigated on the soil in organic carbon content and humus composition.There were 4treatments including:only applying nitrogen fertilizer(M0),50% nitrogen fertilizer+50% spent mushroom culture residues(M1),only spent mushroom culture residues as fertilizer(M2)and double amount spent mushroom culture residues(M3).The results showed that the soil organic carbon,humic acid(HA),fulvic acid(FA)and humin(HM)were increased in 0-20 cm soil layer by applying spent mushroom culture resides as fertilizer for three years.Comparing with applying nitrogen fertilizer alone(M0),the indices were increased for 43.10%-104.21%,52.89%-157.14%,31.07%-74.30% and 44.96%-107.35%,respectively.These increases were not detected significantly in 20-40 cm soil layer.The E4/E6 ratio and△logK of soil increased significantly in humic acid for M2 and M3treatments but not in fulvic acid of various treatments.The findings indicate that applying spent mushroom culture residues as fertilizer may conduce to organic carbon accumulation in the soil,in addition to promote the process of soil humification.