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 and 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, 通过在径流小区中布设土壤水分传感器和土壤水样采集装置, 研究坡耕地在裸地对照(CK)、玉米地均匀施肥(UF)和玉米地非均匀施肥(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)相同处理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, 相较于UF处理, 相同坡位相同土层深度NUF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)相同坡位施氮(UF和UNF)处理距地表20 cm深度处氮素浓度高于40 cm深度处; CK处理各观测点硝态氮浓度均值低于UF和NUF处理, 总氮浓度表现出相同趋势, 但氨态氮浓度最高, 氮素整体变化幅度最小; 相同土层深度处UF处理下总氮浓度从坡顶向坡脚递增, NUF处理坡顶、坡中和坡脚总氮浓度在40 cm深度处的差异较小; 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UF处理相比, NUF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特性, 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: This study investigated the effects of different fertilizer application methods on soil water and nitrogen transport, and maize growth in sloping farmland. Soil water sensors and soil water sampling devices were set up in runoff plots to study the characteristics of soil water and nitrogen transport, maize uptake, and utilization of nitrogen on different slopes in sloping farmland under the treatments of no fertilizer application in bare soil (CK), uniform fertilization in maize field (UF), and non-uniform fertilization in maize field (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 depth of the CK treatment, and the degree of moisture fluctuation was the greatest at the 20 cm soil depth at the footslope under the combined effect of rainfall replenishment and evaporation. The coefficients of variation of the soil moisture content at most observation points under the NUF treatments were lower than those under the UF treatments. 2) Under UF and NUF treatments, the nitrogen concentration at 20 cm soil depth was higher than that at 40 cm soil depth. Nitrate nitrogen and total nitrogen concentrations were lower under CK treatment than that under UF and NUF treatments. However, ammoniacal nitrogen concentration under CK treatment was the highest, and the overall nitrogen change was the lowest. Total nitrogen concentration increased from the hilltop to the footslope under the UF treatment, and there were relatively small differences in total nitrogen concentrations among the hilltop, midslope, and footslope at 40 cm soil depth under the NUF treatment. 3) Maize yield and partial factor productivity of nitrogen and nitrogen absorption rate under UF treatment showed an increasing trend from hilltop to footslope. Total nitrogen accumulation at the midslope under NUF treatment reached 31.51 kg∙hm−2, which was higher than that at the footslope and hilltop, and maize yield was also the highest at the midslope. The partial factor productivity of nitrogen and nitrogen absorption rate increased greatly from the hilltop to the footslope under UNF treatment. In particular, the partial factor productivity of nitrogen and nitrogen absorption rate of maize at the footslope in the first season increased by more than three times compared with that at the hilltop. 4) Compared to UF treatment, UNF treatment ensured crop yield and substantially increased the partial factor productivity of nitrogen and nitrogen absorption rates (65.0%–69.0% and 43.8%–104.2%, respectively) based on a 28.6% reduction in fertilizer application. The non-uniform fertilizer application method in sloping farmland improves the crop uptake of nitrogen fertilizer by utilizing the downslope migration of nitrogen, reduces the amount of fertilizer applied while ensuring yield, and provides a scientific basis for scientifically formulating a fertilizer application system in sloping farmland and effectively controlling the loss of nutrients.

     

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