不同施肥方式对坡耕地土壤水氮运移及玉米生长的影响

Effects of different fertilizer application methods on soil water, nitrogen transport and maize growth in sloping farmland

  • 摘要: 为探究坡耕地不同施肥方式对土壤水氮运移和玉米生长的作用, 通过在径流小区中设置土壤水分传感和土壤水样采集装置, 研究坡耕地在裸地对照(CK)、均匀施肥(UF)和非均匀施肥(NUF)处理下不同坡位处土壤水氮运移特征及玉米对氮素的吸收利用情况。结果表明: 1)相同土层深度下坡脚处土壤含水量均值最低(CK处理40 cm土层深度除外), 在降雨补给和蒸发的共同作用下坡脚20 cm土层深度处水分波动程度最大, 相较均匀施肥处理, 相同坡位相同土层深度非均匀施肥处理观测点(坡中40 cm土层深度除外)土壤水分含量的变异系数较小; 2)相同坡位相同施氮处理距地表20 cm深度处氮素含量高于40 cm深度处(CK处理坡脚除外), CK处理各观测点硝态氮(NO3-N)含量均值低于UF和NUF处理, 总氮(TN)含量表现出相同趋势, 但氨态氮(NH4+-N)含量最高, 且氮素整体变化幅度最小, UF处理下总氮含量从坡顶向坡脚递增, NUF处理坡顶、坡中和坡脚处总氮含量无显著差异; 3) UF处理下玉米产量、氮肥偏生产力和氮素吸收率均呈现由坡顶向坡脚递增的趋势, NUF处理下坡中玉米植株总氮累积量达31.51 kg∙hm−2, 高于坡脚和坡顶, 玉米产量也表现出坡中最高, 氮肥偏生产力和氮素吸收率由坡顶向坡脚大幅递增, 尤其第1个玉米季坡脚氮肥偏生产力和氮素吸收率较坡顶提高3倍以上; 4)与均匀施肥处理相比, 非均匀施肥处理在减少28.6%施肥量的基础上, 保证了作物产量, 大幅提升了氮肥偏生产力和氮素吸收率(65.0%~69.0%和43.8%~104.2%)。坡耕地非均匀施肥方式通过利用氮素的顺坡迁移, 改善作物对氮肥的吸收情况, 在保证产量的同时减少了施肥量, 为坡耕地科学制定施肥制度、有效控制养分流失提供了科学依据。

     

    Abstract: To investigate the effects of different fertilizer application methods on soil water and nitrogen transport and on maize growth in sloping farmland, soil water sensing and soil water sampling devices were set up in the runoff plots to study the characteristics of soil water and nitrogen transport and maize uptake and utilization of nitrogen on different slopes in sloping farmland under the treatments of bare (CK), uniform fertilizer application (UF), and non-uniform fertilizer application (NUF). The results showed that: 1) The average soil moisture content at the footslope was the lowest at the same soil layer depth except for the 40 cm soil layer depth of CK treatment, and the degree of moisture fluctuation was the greatest at the 20 cm soil layer depth at the footslope under the combined effect of rainfall replenishment and evaporation. The coefficients of variation of soil moisture content at most observation points under non-uniform fertilization treatment were smaller than that under uniform fertilization treatment. 2) Nitrogen concentration at 20 cm depth from the surface was higher than that at 40 cm depth under each treatment except at the footslope of CK treatment. Nitrate nitrogen (NO3-N) and total nitrogen (TN) concentrations under CK treatment were lower than that under UF and NUF treatments. However, ammoniacal nitrogen (NH4+-N) concentration under CK treatment was the highest, and the overall nitrogen change was the smallest. Total nitrogen concentration increased from the hilltop to the footslope under the UF treatment, and there were no significant differences in total nitrogen concentration between the hilltop, the midslope, and the footslope under the NUF treatment. 3) Corn yield, the partial factor productivity from nitrogen and nitrogen absorption rate under UF treatment showed an increasing trend from the hilltop to the footslope. The total nitrogen accumulation at the midslope under NUF treatment reached 31.507 kg∙hm−2, which was higher than that at the footslope and the hilltop, and the maize yield also showed the highest in the midslope. The partial factor productivity from nitrogen and nitrogen absorption rate increased greatly from the hilltop to the footslope, especially the partial factor productivity from nitrogen and nitrogen absorption rate of the maize at the footslope in the first season increased by more than three times compared with that at thehilltop. 4) Compared with uniform fertilization treatment, the non-uniform fertilization treatment ensured crop yield and substantially increased the partial factor productivity from nitrogen and nitrogen absorption rate (65.0%−69.0% and 43.8%−104.2%) based on a 28.6% reduction in fertilizer application. The non-uniform fertilizer application method in sloping arable land improves crop uptake of nitrogen fertilizer by utilizing the downslope migration of nitrogen, reduces the amount of fertilizer applied while ensuring the yield, and provides a scientific basis for scientifically formulating the fertilizer application system in sloping arable land and effectively controlling the loss of nutrients.

     

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