稻草覆盖和香根草篱对红壤坡耕地土壤酶活性和微生物群落结构的影响

摘要

[目的]明确不同生物水土保护措施下土壤有机碳与土壤微生物种类及功能间的关系.[方法]依托始于2009水土保护年的红壤坡地不同生物水土保护措施的水土保护效果野外试验,利用磷脂脂肪酸方法(PLFA),研究花生等高种植(CK)、香根草篱+花生(H)、稻草覆盖+花生(M)和稻草覆盖+香根草篱+花生(HM)对土壤微生物量和组成以及参与碳循环土壤酶活性、土壤有机碳、活性有机碳的影响.[结果]与CK相比,H、M和HM 3种水土保护措施土壤总有机碳(TOC)、可溶性有机碳(DOC)、土壤微生物量碳(MBC)和微生物熵含量均有增加,香根草篱是增加土壤MBC和微生物熵的主要影响因素.参与碳循环的蔗糖酶(INV)、纤维素酶(CEL)、β-葡糖苷酶(β-Glu)以及微生物量碳酶强度均受到香根草篱的显著影响.PLFA分析表明,与CK相比,H、M和HM显著增加了土壤PLFAs总量(TB)、细菌(B)和放线菌(ACT)的数量,降低了革兰氏阴性菌(GN)/革兰氏阳性菌(GP)比例,尤以HM处理减少幅度最大.主成分分析表明,H和M处理土壤微生物群落结构相近,与CK差别较大.冗余分析(RDA)表明,土壤TOC、MBC与参与碳循环CEL、INV、β-Glu酶的活性均是影响土壤微生物数量和结构的主要因子.[结论]稻草覆盖和香根草篱对红壤坡耕地土壤参与碳循环的酶活性、微生物数量和群落结构有不同影响.%[Objective] The objective of this paper is to clarify the relationship between soil organic carbon and microorganism under different biological water protection measures. [Method] Soil samples were collected from a field soil and water conservation measures experiment, which was started since 2009 with 4 treatments, including peanuts grown in high order (CK), hedgerows+ peanuts (H), mulching+ peanuts (M) and hedgerows+ mulching+ peanuts (HM). Phospholipid fatty acid (PLFA) profiles for each treatment were used to characterize the microbial community structure. Soil organic carbon, microbial biomass carbon, dissolved organic carbon and soil enzyme activities were also determined. [Result] Compared with the CK, all treatments showed total organic carbon, dissolved organic carbon, total microbial biomass carbon and qMB increased. H is the main influence factor on MBC and Qmb. The results showed that H significantly affected the activities of soil invertase, cellulase, β-Glu and intensity of MBC/TOC. Compared with the CK, H, M and HM, PLFA increased the total PLFAs, bacterial and actinomycetes PLFAs, while decreased G- PLFA/G+PLFA, and that was the lowest under HM treatment. Principal components analysis showed that soil microbial community structure was similar to that of H and M, which was larger difference with CK. Redundancy analysis showed that TOC, MBC and enzymes activities of soil CEL, INV, β-Glu were all the main factors affecting the quantity and structure of soil microorganisms. [Conclusion] Microbial biomass, community structure and soil normalized C-acquiring enzyme activity were influenced significantly by straw mulching and vetiver grass hedgerows.