《烟-稻轮作不同施肥土壤N2O排放对水分的响应》

  • 来源专题:农业立体污染防治
  • 编译者: 季雪婧
  • 发布时间:2023-03-02
  • 【目的】水-旱轮作条件中土壤氧化亚氮(N2O)排放对不同施肥处理的响应对补充亚热带地区N2O排放的研究不足具有重要的意义。【方法】本文以亚热带地区长期不同施肥定位试验(烟-稻轮作)土壤为研究对象,设置60%持水量(WHC)+不施肥(UCK)、60%WHC+推荐施肥(UNPK)、60%WHC+高氮施肥(UNhPK)、60%WHC+推荐施肥配施秸秆(UNPKS)、淹水+不施肥(FCK)、淹水+推荐施肥(FNPK)、淹水+高氮施肥(FNhPK)、淹水+推荐施肥配施秸秆(FNPKS)共8个处理,开展室内培养试验,测定土壤N2O排放及微生物相关功能基因丰度变化,探讨不同施肥土壤N2O排放与相关功能基因丰度对水分的响应规律。【结果】结果表明,(1)与CK处理相比,其他施肥处理均显著降低土壤pH,NPKS显著增加土壤有机质(SOM)和全氮(TN)含量;与NPK处理相比,NhPK和NPKS均显著降低土壤碳氮比(C/N)。(2)60%WHC和淹水条件各施肥处理N2O累积排放量分别为0.56~1.44 mg·kg-1和14.89~20.70 mg·kg-1。与60%WHC条件相比,淹水显著促进各施肥处理N2O排放。60%WHC条件下,与NPK处理相比,NPKS处理显著降低N2O排放。(3)两种不同水分条件下,N2O累积排放量与铵态氮(NH4+-N)含量均呈负相关,与硝态氮(NO3--N)含量均呈正相关。(4)相比于UCK处理,UNPK和UNhPK显著提高AOA基因拷贝数,UNPK显著提高AOB基因拷贝数;UNhPK均显著降低nirK、nirS和nosZ基因拷贝数,UNPKS显著降低nirS基因拷贝数。相比于FCK处理,FNPK、FNhPK、FNPKS均显著提高AOA和AOB基因拷贝数,均显著降低nirS的基因拷贝数。(5)淹水各施肥处理AOA、AOB基因拷贝数和(nirK+nirS)/nosZ比值分别为60%WHC各施肥处理的1.80~2.49倍、1.19~2.19倍和1.25~1.42倍,与60%WHC相比,淹水促进硝化菌硝化作用和反硝化作用的强度,导致大量N2O排放;UNPKS处理的(nirK+nirS)/nosZ比值比UNPK低21%,相比于UNPK处理,UNPKS处理降低土壤反硝化作用,减少N2O排放。【结论】本研究结果表明,淹水条件增加了土壤N2O排放,但减弱了施肥对N2O排放影响;低水分条件下化学肥料配施秸秆可以显著减少N2O排放。

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