碳氮管理措施对冬小麦/夏玉米轮作体系作物产量、秸秆腐解、土壤CO_2排放的影响

Effects of Different Carbon and Nitrogen Managements on Yield, Straw Decomposition, Soil CO_2 Flux of the Winter Wheat/Summer Maize

【目的】系统地研究华北平原冬小麦/夏玉米轮作体系对不同碳氮管理措施的响应,为作物增产、土壤培肥、环境友好的"三赢"局面提供数据支持和理论依据。【方法】分别采用Nmin测试法、尼龙网袋埋藏法、静态碱液吸收法研究不同碳氮管理对冬小麦/夏玉米不同时期0—1 m土层硝态氮累积量、秸秆腐解、土壤CO2排放的影响。【结果】基于Nmin测试法的优化碳氮(Nopt,C+Nopt)处理和平衡氮素的碳氮(C+M,C+W)处理在冬小麦产量上为传统碳氮(Ncon,C+Ncon)处理的100.8%—115.9%;在夏玉米产量上,为传统处理的96.0%—116.4%;且能够节省48.2%—70.4%的氮肥用量。传统处理0—1m土层硝态氮累积量最高可达456.7和419.8 kgN.hm-2,而优化处理和平衡处理最高仅为283.3和180.6 kgN.hm-2,传统处理土壤中的硝酸盐被淋洗的风险要远高于优化处理和平衡处理。在低温干燥的冬小麦季,玉米秸秆腐解较慢,最后秸秆腐解率为61.7%—70.1%;在高温多雨的夏玉米季,小麦秸秆腐解较快,最后秸秆腐解率为56.7%—79.3%。土壤CO2排放具有明显的季节性变化,冬小麦季的日平均CO2排放量为4.8—10.8 gC.m-2,而夏玉米季为12.7—20.7 gC.m-2。施有机肥处理的土壤CO2排放量最大,为3 844.2和4 642.3 gC.m-2,且显著高于其它处理。【结论】基于Nmin测试法的优化碳氮管理措施和平衡氮素的碳氮管理措施不仅能够减少氮肥投入,稳定作物产量,还能降低0—1 m土层硝态氮累积量,培肥土壤。

【Objective】The responses of different carbon and nitrogen managements to the winter wheat/summer maize rotation system were systematically studied in North China Plain.It was expected that the research results would provide a theoretic basis and data support for high yield,soil fertility and environment-friendly ＂triple-win＂ goal.【Method】The methods of Nmin test,buried nylon mesh bag and static alkali absorption were adopted for study the effects of different nitrogen fertilizer managements on nitrate accumulation in 0-1 m soil profile,straw decomposition and soil CO2 flux in different periods of winter wheat/summer maize season,respectively.【Result】The results showed that not only the ratios of optimized treatments and balanced treatments to conventional treatments were 100.8%-115.9% for winter wheat yield,and 96.0%-116.4% for summer maize yield,but also could save 48.2%-70.4% nitrogen fertilizer input.The 0-1 m nitrate accumulation from the conventional treatments was the highest,which could reach to 456.7 and 419.8 kgN.hm-2.But the highest 0-1 m nitrate accumulation from the optimized treatments and balanced treatments were only 283.3 and 180.6 kgN.hm-2,respectively.Hence,the soil nitrate leaching risk in the conventional treatments was higher than the optimized treatments and balanced treatments.The decomposition of maize straw in the cold and arid winter wheat season was slow,which the decomposition rate was 61.7%-70.1%.The decomposition of wheat straw in the hot and moist summer maize season was fast,which the decomposition rate was 56.7%-79.3%.Soil CO2 flux had obvious seasonal variation,which the average daily CO2 flux in the winter wheat season was 4.8-10.8 gC.m-2,but 12.7-20.7 gC.m-2 in the summer maize season.The accumulated soil CO2 flux from the balanced treatments with organic fertilizer were the highest,which were 3 844.2 and 4 642.3 gC.m-2,respectively.Furthermore,it was significantly higher than the other treatments.【Conclusion】The optimized and balanced C N managements not only reduced N fertilizer inputs,stabilized crop production but also decrease a the 0-1 m soil nitrate accumulation and cultivating soil fertility.