玉米成熟期黄壤坡耕地径流及其氮素流失特征研究

以顺坡垄作、平作、横坡垄作坡面为研究对象,研究自然降雨条件下,黄壤坡耕地地表径流、壤中流及其氮素流失特征,以期为研究区氮素流失预测和有效防控提供科学依据。结果表明:自然降雨条件下,玉米成熟期平均地表径流量分别为0—20,20—40cm壤中流量的7.96,8.22倍。不同耕作措施间地表径流量和氮素流失量差异显著,地表径流量和氮素流失量均表现为顺坡垄作平作横坡垄作,顺坡垄作坡面地表径流量分别是平作和横坡垄作的1.20,2.07倍,顺坡垄作坡面氮素流失量分别是平作和横坡垄作的1.35,2.06倍。在0—20,20—40cm壤中流中横坡垄作径流量和氮素流失量则明显高于其他耕作措施坡面,在0—20cm壤中流中横坡垄作氮素流失量分别是顺坡垄作和平作的2.45,1.90倍;在20—40cm壤中流中横坡垄作氮素流失量分别是顺坡垄作和平作的2.34,1.79倍。地表径流为氮素流失的主要途径,可溶态氮为氮素流失的主要形式,占总氮流失量的63.84%～72.61%;硝态氮是坡耕地无机氮流失的主要成分,占总氮流失量的16.47%～59.17%。氮素流失量与径流量和降雨量均呈显著线性正相关关系。研究区自然降雨条件下,横坡垄作能有效减少氮素流失,合理的耕作措施有助于防治研究区水土资源和氮素流失。

Characteristics of Runoff and Nitrogen Losses in Yellow Soil Sloping Cropland at Mature Stage of Maize

The study took down slope ridge planting, flat planting, and cross ridge planting as the study object, studied the characteristics of surface runoff, interflow and nitrogen loss under natural rainfall conditions in the yellow soil area, and intended to provide the theoretical basis for predicting and preventing nitrogen loss. The results showed that:The average surface runoff at maize mature stages was 7.96 times and 8.22 times higher than the interflow in 0-20 cm and 20-40 cm soil depths under the conditions of natural rainfall. The surface runoff and nitrogen loss were significantly different under different tillage measures. The surface runoff and nitrogen loss were in order of down slope ridge planting > flat planting > cross ridge planting. The surface runoff of down slope ridge planting was 1.20 times and 2.07 times higher than that of flat and cross ridges planting respectively. Nitrogen loss in down slope ridge planting was 1.35 times and 2.06 times higher than that of flat and cross ridge planting. Under cross ridge planting, the interflow and nitrogen loss of the 0-20 cm and 20-40 cm soil depths were significantly higher, and nitrogen loss in 0-20 cm soil depths was 2.45 times and 1.90 times higher than that of down slope ridge and flat planting respectively, while nitrogen loss in the 20-40 cm soil depths was 2.34 times and 1.79 times higher than that of down slope ridge and flat planting respectively. Surface runoff was the main channel for nitrogen loss. The dissolved nitrogen accounted for 63.84%~72.61% of the total nitrogen loss, and was the main form of nitrogen loss. Nitrate nitrogen accounted for 16.47%~59.17% of the total nitrogen loss, and was the main form of inorganic nitrogen loss. There were significant linear positive correlations between nitrogen loss and runoff, rainfall. Cross ridge planting was an effective way to decrease nitrogen loss under the condition of natural rainfall and reasonable tillage measure can protect water and soil resources and prevent nitrogen loss in the study region.