小麦-玉米轮作体系中秸秆还田方式对土壤肥力及作物产量的影响

Effects of different models of straw returning to fields on soil carbon stock,soil nutrients and crop yield in wheat-maize cropping system

【目的】探讨小麦-玉米轮作体系下不同秸秆还田方式对土壤肥力和作物产量的影响,旨在为促进小麦-玉米连续轮作区的农业可持续发展提供理论依据。【方法】在陕西关中地区,于2008-2010年采用2年4季的田间定位试验,以玉米秸秆不还田-小麦秸秆不还田为对照(CK),比较玉米秸秆覆盖还田-小麦秸秆高留茬还田(T-1)、玉米秸秆直接还田-小麦秸秆高留茬还田(T-2)、玉米秸秆直接还田-小麦秸秆直接还田(T-3)3种秸秆还田方式对土壤碳储量、养分含量及作物周年产量的影响。【结果】与CK相比,3种秸秆还田方式下耕层(0～20cm)土壤总有机碳储量(CT)、土壤活性有机碳储量(CL)、土壤碳库管理指数(CMI)及土壤全磷、硝态氮、速效钾含量和作物周年产量均增加。3种秸秆还田方式对CT、CL及CMI的影响表现为T-3>T-2>T-1;对作物周年产量的影响则表现为T-2>T-3>T-1;对土壤养分的影响无明显规律性,但是对速效钾含量的影响表现为T-2>T-3>T-1。【结论】综合考虑,在陕西关中小麦-玉米轮作体系中,玉米秸秆直接还田-小麦秸秆高留茬还田模式(T-2)是较优的耕作方式。

【Objective】 Investigating the effects of different straw returning models on soil fertility and crop yield is very vital,and can provide references for theory of sustainable agricultural development in continuous winter wheat-summer maize rotation system area.【Method】 The research was carried out continuously from 2008 to 2010 in Guanzhong Plain.There were four treatments including 3 straw management models,namely,T-1：maize straw mulching-high wheat stubble retention,T-2：maize straw chopping-high wheat stubble retention,T-3：maize straw chopping-wheat straw chopping,and no maize and wheat straw returning was designed as CK.The soil total carbon storage（CT）,soil labile carbons（CL） storage,soil carbon management index（CMI） and soil chemical fertilizer content were determined.And the annual crop yield was recorded.【Result】 Straw returning treatments showed obvious influence on CT,CL,CMI,soil total P,soil NO-3,soil available K content and annual crop yield within 2 years.The difference among the three straw mulching models showed the trend of T-3〉T-2〉T-1 for CT,CL storage,and CMI;whereas,the observed trend was T-2〉T-3〉T-1 in the case of annual grain yield and available K contents in soil;different straw returning model did not show significant effect on other soil chemical fertilizer contents.【Conclusion】 The results indicate that,T-2 is the optimized straw management in the winter wheat-summer maize annual double cropping areas in Guanzhong plain of China