秸秆还田种类对稻田N_(2)O排放及硝化反硝化微生物的影响

Effects of Returned Straw Type on N2O Emission,Nitrification and Denitrification Microorganisms from Paddy Field

以太湖流域典型单季稻田的原状土柱为研究对象,通过设置温室土柱试验,同步监测3种秸秆(水稻秸秆RS、小麦秸秆WS、玉米秸秆MS)施用下水稻各生长期N_(2)O排放、水稻产量和土壤理化因子,同时定量化分析多个N_(2)O排放相关菌群及功能基因的丰度,以阐明N_(2)O排放对不同种类秸秆施用引发的微生物响应机制,筛选控制单季稻田N_(2)O减排增效最佳的秸秆种类。结果表明:与对照相比,RS、WS和MS处理下水稻生长期N_(2)O排放量分别增加162.32%、107.11%和9.48%,其中RS处理显著高于MS处理。水稻生育期内,土壤氨氧化菌(AOA、AOB)和反硝化菌群落(nirS、nosZ)丰度均呈现先上升后下降的变化趋势。与对照相比,拔节期RS处理显著增加AOA、AOB、nirS和nosZ拷贝数,MS和WS处理对上述功能基因丰度均无显著影响。各生育期土壤NH_(4)^(+)-N含量整体高于NO_(3)^(–)-N含量,二者均在水稻分蘖期达到峰值,而后随水稻生长不断降低,同一时期不同秸秆处理之间二者无显著性差异。相关性分析和结构方程模型(SEM)结果表明,土壤AOB丰度和土壤NH_(4)^(+)-N含量是直接影响稻田土壤N_(2)O排放的主要因素。综合考虑不同类型秸秆还田后土壤理化因子、水稻产量和微生物丰度变化,玉米秸秆是减缓太湖流域单季稻田N_(2)O排放且提高产量的最优秸秆还田种类。

The original soil columns of a typical single-cropping paddy field in the Taihu Lake Basin were used as the research object,N_(2)O emission,rice yield and soil physiochemical properties were monitored under the application of three straw types(rice straw-RS,wheat straw-WS and maize straw-MS),and the abundances of multiple functional genes related to N_(2)O emission were quantified to clarify soil microbial mechanism of N_(2)O emission under different straw types.The results showed that RS,WS and MS treatments increased N_(2)O emissions by 162.32%,107.11%and 9.48%,respectively,in which RS was significantly higher than those from MS treatment.The abundance of ammonia oxidizing bacteria and ammonia oxidizing archaea(AOA,AOB)and denitrifiers communities(nirS,nosZ)all showed a similarly change,increasing first and then decreasing with rice growth.Compared with CK treatment(no straw),RS treatment significantly increased the abundances of AOA,AOB,nirS and nosZ by 6.14,8.26,4.82 and 16.96 times in the elongation stage,respectively,while no significant response was found in either MS or WS treatment.Soil NH_(4)^(+)-N content was generally higher than NO_(3)^(–)-N during rice growth,with an increasing pattern until the tillering stage,and then decreased with rice growth,while no significant difference was found among different straw treatments.The results of correlation analysis and the Structural Equation Modeling(SEM)showed that AOB abundance and soil NH_(4)^(+)-N content were the main factors affecting N_(2)O emission in paddy field.Considering the comprehensive results of soil physiochemical properties,rice yield and soil microbial abundance,maize straw is the most appropriate for N_(2)O emission mitigation and yield enhancement of single-cropping paddy field in the Taihu Lake Basin.