冀中南地区小麦——玉米轮作体系秸秆还田下适宜施氮量的研究

Study on the Suitable Nitrogen Application Rate under Straw Returning to the Field in Wheat-Maize Rotation System in the Central and Southern Hebei

为探明冀中南地区秸秆还田条件下小麦—玉米轮作体系的适宜施氮量,为高效利用秸秆资源和优化施肥技术提供理论依据,在玉米秸秆还田的基础上进行了小麦—玉米轮作周期的不同氮肥施用量试验。小麦季和玉米季的施氮量均设不施、低氮、中氮、高氮(当地常规施肥)4个处理,研究了不同施氮量处理对2种作物子粒产量、茎叶产量、氮素积累量和氮素收获指数的影响;并对各作物施氮量与其子粒产量的关系进行拟合,根据施氮量—产量的二元函数方程,计算得到每种作物的最佳施氮量和最佳产量。结果表明:秸秆还田后2种作物的千粒重、子粒产量、茎叶产量、子粒氮素积累量和氮素收获指数均随施氮量的增加呈先升高后降低的变化,指标值均以中氮处理最高;根据施氮量—子粒产量的耦合曲线,得到该地区小麦的最佳施氮量为152.47 kg/hm^(2)、最佳产量为9346.44 kg/hm^(2),玉米的最佳施氮量为188.31 kg/hm^(2)、最佳产量为11219.78 kg/hm^(2)。在冀中南地区小麦—玉米轮作体系下,玉米秸秆还田后2种作物均应适当降低施氮量,小麦施氮量为152.47 kg/hm^(2)、玉米施氮量为188.31 kg/hm^(2)时效果最佳,可达到肥料减施和产量提高的双重效果。

In order to explore the suitable nitrogen application rate for the wheat-maize rotation system under the condition of straw returning to the field in the central and southern Hebei,and to provide a theoretical basis for efficient utilization of straw resources and optimization of fertilization techniques,the experiments were conducted on different nitrogen application rates in the wheat-maize rotation cycle after straw returning to the field.The nitrogen application rates for both wheat and maize seasons were set at four treatments:no application,low nitrogen,medium nitrogen,and high nitrogen(local conventional fertilization).The effects of different nitrogen application rates on grain yield,stem and leaf yield,nitrogen accumulation,and nitrogen harvest index of the two crops were studied.The relationship between nitrogen application rate and grain yield of each crop was fitted,and the optimal nitrogen application rate and yield of each crop were calculated based on the binary function equation of nitrogen application rate and yield.The results showed that the 1000-grain weight,grain yield,stem and leaf yield,grain nitrogen accumulation,and nitrogen harvest index of the two crops after returning straw to the field increased first and then decreased with the increase of nitrogen application rate.The index values were the highest in the medium nitrogen treatment.According to the coupling curve between nitrogen application rate and grain yield,the optimal nitrogen application rate for wheat in this region was 152.47 kg/hm^(2),and the optimal yield was 9346.44 kg/hm^(2).The optimal nitrogen application rate for corn was 188.31 kg/hm^(2),and the optimal yield was 11279.38 kg/hm^(2).Under the wheat-maize rotation system in the central and southern regions of Hebei,the nitrogen application rate for both crops should be appropriately reduced after returning corn straw to the field.The best effect is achieved when the nitrogen application rate for wheat was 152.47 kg/hm^(2) and for maize was 188.31 kg/hm^(2),which can achieve a dual effect of fertilizer reduction and yield improvement.