Effects of inter-row planting grasses on soil organic carbon fractions and soil microbial community of apple orchard in Weibei dryland

Two perennial legumes (hairy vetch and white clover) and two perennial grasses(ryegrass and bluegrass) were sown in inter\|rows of apple orchard in Weibei dryland. Soil samples were taken from 0-100 cm soil layers to study the effects of planting grasses on various soil organic carbon fractions and soil microbial community with clean tillage as control. Results showed that planting grasses could significantly increase soil total organic carbon content, particulate organic carbon content, light fraction organic carbon content, readily oxidizable organic carbon content, dissolved organic carbon content and microbial biomass carbon content in 0-40 cm soil layer. The contents of soil organic carbon fractions in perennial legume were mostly higher than perennial grass. Soil total organic carbon contents of perennial legume and perennial grass increased 1.2 g/(kga) and 0.9 g/(kga) in 0-20 cm soil layer, respectively. The AWCD, Shannon index (H) and Richness index (S) in the planting grass treatments were higher than the clean tillage, in which the microbial activity of perennial legume was higher. Therefore, growing grasses could improve soil organic carbon content, diversity of soil microbial community, the utilization rate of carbon source and richness of soil microbial community, in which perennial legumes (hairy vetch and white clover) increased more significantly.