添加作物秸秆对土壤有机碳组分和酶活性的影响

Effects of crop straws on soil organic carbon components and enzyme activities

【目的】研究小麦和玉米秸秆以不同方式还田对土壤有机碳及其组分和酶活性的影响,为寻求最佳秸秆还田方式提供依据。【方法】采用室内恒温培养法,以连续7季秸秆均还田土及不还田土为供试土壤,研究培养60d后,小麦、玉米秸秆与土壤混匀还田和覆盖于表层还田对土壤总有机碳(TOC)、活性有机碳(LOC)、微生物量碳(MBC)含量,LOC/TOC、MBC/TOC和土壤蛋白酶(PROT)、脱氢酶(DHA)活性的影响。【结果】与不添加作物秸秆相比,无论以何种方式还田,添加小麦或玉米秸秆均明显增加了还田土与不还田土的TOC、LOC、MBC含量,LOC/TOC、MBC/TOC和PROT、DHA活性。还田土的TOC、LOC、MBC含量和PROT、DHA活性均明显高于不还田土;添加小麦秸秆处理土壤的TOC、LOC含量明显高于添加玉米秸秆处理;秸秆与土壤混匀还田处理的TOC、LOC含量和PROT、DHA活性均明显高于秸秆覆盖于表层还田处理;秸秆类型和还田方式对MBC含量、MBC/TOC无显著影响。作物秸秆腐解过程中LOC含量和PROT活性可较为敏感地反映土壤有机碳和微生物活性的变化。【结论】无论是在还田土还是不还田土中,作物秸秆与土壤混匀还田均有利于提高土壤有机碳各组分含量和土壤酶活性。

【Objective】The study aimed to evaluate the effects of different returning methods of wheat and maize straws on soil organic carbon(SOC)components and enzyme activities for seeking optimal straw returning method.【Method】Two soils(S1:straw-amended soil with straw-returning,and S2:soil without straw-returning)were sampled from a seven-season summer maize/winter wheat rotation system on Guanzhong Plain,Shaanxi,China.Equal amounts of wheat or maize straws were incorporated into soil or covered on surface to study changes in contents of soil total organic carbon(TOC),labile organic carbon(LOC),and microbial biomass carbon(MBC),ratios of LOC/TOC and MBC/TOC,and activities of protease(PROT)and dehydrogenase(DHA)over a 60-day incubation period.【Result】Compared with treatments without crop straw-returning,contents of TOC,LOC,and MBC,ratios of LOC/TOC and MBC/TOCand activities of enzymes were significantly increased by adding crop straw regardless of soil types and straw-returning methods.Contents of TOC,LOC,and MBC and enzyme activities in S1 were significantly higher than those in S2.Soils with amended wheat straw had higher contents of TOC and LOC than those with maize straw.Contents of SOC components and enzyme activities with crop straw incorporated were higher than those with crop straw on soil surface.However,soil types and straw-returning methods had no significant effect on MBC and MBC/TOC.【Conclusion】Treatment with crop straw incorporated to soil improved contents of SOC components and soil enzyme activities.