基于产量和环境友好的黄土高原半干旱区玉米氮肥投入阈值研究

Determination of the input threshold of nitrogen fertilizer based on environment-friendly agriculture and maize yield

为确定黄土高原半干旱区玉米的合理氮肥投入阈值,采用田间试验和室内分析方法,在甘肃省定西市安定区连续3年定位研究了不同施氮量对玉米产量、土壤矿质氮累积量、土壤氮素表观平衡等的影响。结果表明,施用氮肥对玉米有显著的增产作用,施氮量为243.72 kg·hm^(-2)时,玉米产量最高,为8139.65 kg·hm^(-2)。之后随施氮量的增加,玉米产量不增反降,产量与施氮量呈显著的二次抛物线关系;土壤矿质氮累积量与施氮量呈极显著指数相关关系,在200 cm土层内的累积量随施氮量及施氮年限的增加而增大,施氮量为270 kg·hm^(-2)时,矿质氮累积量为563.01 kg·hm^(-2),显著高于施氮量为180、225 kg·hm^(-2)处理的矿质氮累积量(410.88、480.97 kg·hm^(-2));氮表观平衡值与施氮量呈极显著线性正相关。氮素表观平衡值为0时,施氮量为179.50 kg·hm^(-2)。施氮量在179.50~243.72 kg·hm^(-2)时,玉米产量为7925.14~8139.65 kg·hm^(-2),土壤矿质氮累积量为409.83~513.08 kg·hm^(-2),氮素平衡值为0~49.15 kg·hm^(-2)。综合分析提出,施氮量为179.50~243.72 kg·hm^(-2)是黄土高原半干旱区既保证玉米高产稳产又保证土壤氮素盈余及矿质氮残留较少,可实现环境安全的氮肥投入阈值。

The semi-arid region of Loess Plateau is vast and acts as one of the main areas of grain production in China.In this study,field experiments in the Anding District of Gansu Province in China were conducted to explore the effects of different nitrogen application rates on maize yield,soil mineral nitrogen accumulation,and soil nitrogen surplus rate,to determine the high-yield and environmentally friendly optimal nitrogen application rate(ONR)for maize fields.The results showed that the application of nitrogen fertilizer had a significant effect on the yield of maize.When the nitrogen application rate was 243.72 kg·hm^(-2),the yield of maize was the highest,at 8139.65 kg·hm^(-2).Later,with the increase of nitrogen application rate,the corn yield decreased,and the relationship between maize yield and nitrogen application rate showed a significant quadratic parabolic relationship;the cumulative amount of soil mineral nitrogen in the 200 cm soil layer increased with the increase of nitrogen application rate and the period of nitrogen application.The cumulative amount of soil mineral nitrogen had a significant exponential correlation with nitrogen application rate.When the nitrogen application rate was 270 kg·hm^(-2),the soil mineral nitrogen accumulated to 563.01 kg·hm^(-2),which was significantly higher than 410.88 kg·hm^(-2) and 480.97 kg·hm^(-2),achieved under the nitrogen application rate of 180 kg·hm^(-2) and 225 kg·hm^(-2);thus,the nitrogen surplus rate was positively linearly correlated with the nitrogen application rate.When the nitrogen surplus rate was 0,the nitrogen application rate was 179.50 kg·hm^(-2).When the nitrogen application rate was 179.50~243.72 kg·hm^(-2),the maize yield was 7925.14~8139.65 kg·hm^(-2),soil mineral nitrogen accumulation was 409.83~513.08 kg·hm^(-2),and the nitrogen surplus rate was 0~49.15 kg·hm^(-2).Based on the comprehensive analysis,when the threshold of ONR is 179.50~243.72 kg·hm^(-2) in the semi-arid area of the Loess Plateau,a high and stable yield of maize was achieved,and the residual of soil mineral nitrogen was reduced.