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通过8年田间小区定位试验研究不同施氮量处理对土壤硝态氮分布、累积以及作物产量的影响。结果表明,在小麦-玉米轮作8个周期后,0～200 cm土体中各土层的硝态氮含量变化规律为N575>N400>N225>N0,随着土壤深度的增加,在0～80 cm土层各施氮量处理土壤硝态氮均呈下降趋势,各处理在60～80 cm降到最低。各施氮量处理在80～200 cm土壤硝态氮随着土壤深度的增加均呈先升高后降低的趋势,同一土层不同施氮量处理间硝态氮的差异明显增大。经过8个小麦玉米轮作周期后,N575处理100～200 cm土壤硝态氮累积量所占总累积量的比例提高15.18%。通过对施氮量与土壤硝态氮累积量用数学模型模拟,发现二者符合线性关系,施氮量与土壤硝态氮累积量的回归方程为y=1.34x+75.58(R2=0.84**)。从冬小麦-夏玉米轮作周期考虑,全年的适宜施氮量为400kg/hm2。综合考虑施氮量对土壤硝态氮的残留量与作物产量的影响,提出华北平原区小麦-玉米轮作周期中总施氮量应控制在225～400 kg/hm2之间,基本上能控制土壤硝态氮向深层土壤的淋失,能明显降低土壤硝态氮向地下水淋失的风险。
The effects of different N application rates on the distribution and accumulation of NO3 - N in soil and crop yield were studied by field experiment in 8 years. The results showed that after 8 cycles of wheat-corn rotation, the variation of NO3 - N in soil layers from 0 ~ 200 cm was N575> N400> N225> N0. With the increase of soil depth, The nitrate content in soil decreased with the application of nitrogen fertilizer, and the treatment decreased to the lowest at 60 ~ 80 cm. The nitrate content in the soil of 80 ~ 200 cm increased at first and then decreased with the increase of soil depth under different nitrogen application rates. The difference of nitrate nitrogen in different nitrogen application rates increased significantly in the same soil layer. After 8 cycles of wheat and corn rotation, the proportion of N575 accumulated nitrate nitrogen accumulation in 100 ~ 200 cm soil increased by 15.18%. Through the mathematical model simulation of nitrogen application and soil nitrate accumulation, the regression equation was found to be y = 1.34x + 75.58 (R2 = 0.84 ** ). Considering the rotation period of winter wheat-summer maize, the suitable nitrogen application rate for the whole year is 400kg / hm2. Considering the effect of nitrogen application rate on soil nitrate nitrogen residual and crop yield, it was proposed that the total N application rate should be controlled between 225 and 400 kg / hm2 during wheat-corn rotation in North China Plain, Leaching of nitrate to deep soil can significantly reduce the risk of leaching of nitrate from soil to groundwater.