秸秆还田配施腐秆剂下不同氮肥运筹对土壤养分及活性有机碳库的影响

Effects of different nitrogen application methods on soil nutrients and labile organic carbon pool under the condition of straw returning with straw-decomposing microbial inoculant

为探明秸秆促腐还田条件下沿淮地区不同氮肥运筹对土壤养分及活性有机碳库的影响,为秸秆还田后氮肥的合理施用提供依据,通过沿淮麦田的定位试验,设置4个处理,分别为稻秸还田+腐秆剂(CN_(52),C/N=52∶1)、稻秸还田+腐秆剂+增基减拔施N肥(CN_(11),C/N=11∶1)、稻秸还田+腐秆剂+常规施肥(CN_(17),C/N=17∶1)和稻秸还田+腐秆剂+减基增拔施N肥(CN_(22),C/N=22∶1),并对耕层土壤养分、不同形态碳素、不同形态碳素有效率和碳库管理指数等进行分析。结果发现:土壤碱解氮以CN_(17)最高,为166.23 mg·kg^(-1),而土壤速效磷和速效钾以CN_(11)最高,分别为22.12和138.75 mg·kg^(-1);土壤总有机碳、活性有机碳、可溶性有机碳、活性有机碳有效率和可溶性有机碳有效率均以CN_(11)最高,分别为15.52 g·kg^(-1)、11.87 g·kg^(-1)、38.04μg·kg^(-1)、76.49%和0.25%;土壤碳库管理指数也以CN_(11)最高,为204.19;土壤养分含量、碳素有效率与土壤碳库指数的相关性最高。总之,沿淮地区稻秸促腐还田施用氮肥调节土壤初始C/N至11时,土壤养分含量、有机碳中活性组分含量及其有效率和土壤碳库管理指数的提升效果最大。

In order to provide a basis for rational application of nitrogen fertilizer after straw returning,a field experiment was carried out in area along Huaihe River to explore the effects of different nitrogen application methods on soil nutrients and labile organic carbon pool under the condition of straw returning with straw-decomposing microbial inoculant.Four treatments:rice straw returning+straw-decomposing microbial inoculant(CN_(52),C/N=52:1),rice straw returning+straw-decomposing microbial inoculant+fertilized more N base fertilizer(CN_(11),C/N=11:1),rice straw returning+straw-decomposing microbial inoculant+recommended N fertilizer(CN_(17),C/N=17:1)and rice straw returning+straw-decomposing microbial inoculant+fertilized less N base fertilizer(CN_(22),C/N=22:1)were set to analyze soil nutrients,different forms of carbon,different forms of carbon efficiency and carbon pool management index.The results showed that:CN_(17) treatment had the highest soil available N,which was 166.23 mg·kg^(-1),CN_(11) treatment had the highest soil available P and K,which were 22.12 and 138.75 mg·kg^(-1),respectively;CN_(11) treatment had the highest soil total organic carbon,labile organic carbon,soluble organic carbon,labile organic carbon efficiency and soluble organic carbon efficiency,which were 15.52 g·kg^(-1),11.87 g·kg^(-1),38.04μg·kg^(-1),76.49%and 0.25%,respectively;the highest carbon pool management index(CPMI)of CN_(11) was 204.19;correlation analysis showed that the soil nutrient content and carbon efficiency were better related to the soil carbon pool index(CPI).In conclusion,under the condition of rice straw returning to promote decay in region along Huaihe River,applying nitrogen fertilizer to adjust the initial C/N ratio of soil to 11 is the most effective way to improve soil nutrient content,the content and efficiency of labile components in organic carbon and soil carbon pool management index.