Effects of Different Mulching on Soil Organic Carbon Fractions and Soil Microbial Community of Apple Orchard in Loess Plateau

【Objective】The objective of this study was to investigate the characteristics of soil total organic carbon,labile organic carbon and soil microbial community under different mulching treatments for one to three years in apple orchards in the Loess Plateau.【Method】Long-term orchard experiments were carried out,and soil samples were taken from 0-100 cm soil layers to study the effects of different mulching treatments on various soil organic carbon fractions and soil microbial community.The experiment consists of three mulching treatments: straw mulching,black plastic-film mulching,and bare tillage.【Result】Compared with bare tillage,straw mulching significantly increased soil total organic carbon contents,particulate organic carbon contents,light fraction organic carbon contents,dissolved organic carbon contents and readily oxidizable organic carbon content in 0-60 cm soil layers,and increased with the increased years of coverage in one to three years,in which soil total organic carbon contents increased by 1.9 g.kg-1 per year in 0-20 cm soil layers.But the microbial biomass carbon contents tended to decrease with the increased years of coverage.In the black plastic-film mulching treatment,soil total organic carbon contents were less than the control,but labile organic carbon contents were higher than the control.Soil total organic carbon contents and labile organic carbon contents both decreased with the increased years of coverage,soil total organic carbon contents decreased by 0.91 g.kg-1in 0-20 cm soil layers after three years.The results showed that AWCD,Shannon index(H) and Richness index(S) in the straw mulching and plastic-film mulching treatments were higher than the bare tillage,and also decreased with the increased years of coverage.The plastic-film mulching decreased significantly.【Conclusion】Straw mulching could improve soil organic carbon contents while black plastic-film mulching reduced soil organic carbon contents.Two mulching treatments both increased the diversities of soil microbial community,the utilization rate of carbon source,richness of soil microbial community,and also decreased with the increased years of coverage.But the black plastic-film mulching treatments showed more obviously.