菌剂降解秸秆直接还田对黑土土壤碳素和氮素的影响

Effects of Agent Degrading Straw and Returning to Black Soil on Carbon and Nitrogen

[目的]通过3年菌剂降解秸秆直接还田试验,研究了东北黑土土壤碳素和氮素的变化。[方法]采用TOC仪和凯式定氮仪,测定土壤有机质、全氮、微生物量碳和微生物量氮。[结果]与初始的基础肥力相比,各处理土壤有机质含量均有所增加,分别提高了23.39%、18.23%和15.96%。各处理土壤微生物量碳含量在灌浆期达到最高,复合菌处理和纤维素分解菌处理明显高于对照,分别是对照的1.24倍和1.17倍。除2011年施菌剂处理土壤全氮含量显著低于对照外,2010年和2014年施菌剂处理土壤全氮含量均高于对照。土壤微生物量氮含量由大到小依次为复合菌>纤维素分解菌>对照。随着菌剂降解秸秆直接还田年份的增加,各处理土壤的C/N均有所提高,且2014年各处理土壤的C/N显著高于2010年和2011年,接近于微生物降解的最佳C/N(25∶1)。[结论]菌剂降解秸秆直接还田增加了土壤有机质、微生物量碳、全氮、微生物量氮含量和C/N,且2014年各处理土壤的C/N接近于25∶1。

[Objective] Experiments of three years was conducted to study the effects of agent degrading straw and returning to black soil on carbon and nitrogen. [Method]Instruments such as TOC and kjeldahl apparatus were used to measure organic matter content,microbial biomass carbon content,total nitrogen content,and microbial biomass nitrogen content. [Result] Organic matter contents of all the treatments were higher than those of initial fertilities by 23. 39%,18. 23% and 15. 96%,respectively. Microbial biomass carbon contents of each treatment were the greatest in grain filling geried. Microbial biomass carbon contents of compound bacterium agent treatment and cellulose decomposing bacteria treatment were higher than that of CK by 1. 24 times and 1. 17 times. Total nitrogen contents in the agent degrading straw treatments in 2010 and 2014 were higher than that of CK,but total nitrogen contents of the agent degrading straw treatments in 2011 were lower than that of CK. Microbial biomass nitrogen content of compound bacterium agent treatment was the highest,that of cellulose decomposing bacteria treatment was the second,and that of CK was the lowest. With three years of agent degrading straw and returning to black soil,C / N of the three treatments all increased. C / N of all the treatments in 2014 which was approached 25∶1 were the best and higher than those in 2010 and2011. [Conclusion] Organic matter,microbial biomass carbon,total nitrogen,microbial biomass nitrogen and C / N were increased by treatments of agent degrading straw and returning to black soil and C / N of all the treatments in 2014 which was approached 25∶1.