Effects Of Different Mulching And Inter-row Planting Grasses On Soil Organic Carbon Fractions And Soil Microbial Community Of Apple Orchard In Loess Plateau

The objective of this study was to investigate the characteristics of soil total organiccarbon, labile organic carbon and soil microbial community under different mulchingtreatments in one to three years at apple orchard in Loess Plateau. Long-term orchardexperiments have been carried out, and soil samples were taken from0-100cm soil layers tostudy the effects of different mulching on various soil organic carbon fractions and soilmicrobial community. The experiment consists of three mulching treatments: straw mulching,black plastic-film mulching, and bare tillage. Compared with bare tillage, straw mulchingcould significantly increase soil total organic carbon contents, particulate organic carboncontents, light fraction organic carbon contents, dissolved organic carbon contents and readilyoxidizable organic carbon contents in0-60cm soil layers, and increased with the increase ofthe coverage of years in one to three years, in which soil total organic carbon contentsincreased1.9g/kg per year in0-20cm soil layers. But microbial biomass carbon contentstend to decrease with the increase of the coverage of years. In black plastic-film mulchingtreatment, soil total organic carbon contents were less than the control, but labile organiccarbon contents were higher than the control. Soil total organic carbon contents and labileorganic carbon contents both decreased with the increase of the coverage of years, soil totalorganic carbon contents decreased0.91g/kg in0-20cm soil layers after three years. Theresults showed that AWCD, Shannon index (H) and Richness index (S) in the straw mulchingand plastic-film mulching treatments were higher than the bare tillage, and also decreasedwith the increase of the coverage of years. The plastic-film mulching decreased significantly.The result showed that straw mulching could improve soil organic carbon contents whileblack plastic-film mulching reduced soil organic carbon contents. Two mulching treatmentsboth increased the diversities of soil microbial community, the utilization rate of carbonsource, richness of soil microbial community, and also decreased with the increase of thecoverage of years. But the black plastic-film mulching treatments showed more obviously.Two perennial legumes (hairy vetch and white clover) and two perennialgrasses(ryegrass and bluegrass) were sown in inter-rows of apple orchard in Weibei dryland. Soil samples were taken from0-100cm soil layers to study the effects of planting grasses onvarious soil organic carbon fractions and soil microbial community with clean tillage ascontrol. Results showed that planting grasses could significantly increase soil total organiccarbon contents, particulate organic carbon contents, light fraction organic carbon contents,readily oxidizable organic carbon contents, dissolved organic carbon contents and microbialbiomass carbon contents in0-40cm soil layer. The contents of soil organic carbon fractionsin perennial legume were mostly higher than perennial grass. Soil total organic carboncontents of perennial legume and perennial grass increased1.2g/kg per year and0.9g/kg peryear in0-20cm 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 microbialactivity of perennial legume was higher. Therefore, growing grasses could improve soilorganic carbon contents, diversity of soil microbial community, the utilization rate of carbonsource and richness of soil microbial community, in which perennial legumes (hairy vetchand white clover) increased more significantly.