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氮素流失是农业面源污染的重要来源.为了解四川盆地紫色丘陵区不同种植模式下氮的流失特征,以四川盆地紫色丘陵区4种典型耕作模式紫云英-水稻(M1)、空地-大豆-空地(M2)、空地-生姜(M3)、空地-玉米+红薯(M4)等为研究对象,研究了4种模式从2008年12月到2009年8月共8次有效降雨中氮通过地表径流和渗透水的流失特征.研究期间,4种模式下氮流失量随着降雨量的增加而增加,总氮流失量表现为:M3((30.388±2.86)kg·hm-2)>M4((17.118±1.677)kg·hm-2)>M2((10.987±1.108)kg·hm-2)>M1((6.090±1.051)kg·hm-2).相对于其它模式,M4模式下地表径流量和渗透水量在研究期间均最大,但M3模式下氮通过地表径流和渗透水的流失量最大.另外,非生长季节4个模式下氮流失量相对较低且各模式间差别较小,生长季节4个模式间可溶性氮和总氮通过地表径流和渗透水流失量均表现为M3>M4>M2>M1.4种种植模式下氮通过地表径流和渗透水的流失形态均以硝态氮为主.渗透水中铵态氮和可溶性总氮占总氮的比例高于地表径流.这些结果为该区区域合理选择耕作模式、优化耕作方式、加强管理以控制区域农业面源污染提供了一定的基础数据.
Nitrogen loss is an important source of agricultural non-point source pollution.To understand the characteristics of nitrogen loss under different planting modes in the purple hilly area of Sichuan Basin, four typical cultivation patterns of Astragalus-to-rice (M1), open land- Soybean - open field (M2), open ground - ginger (M3), open field - corn + sweet potato (M4) were studied in this study. Surface runoff and seepage water loss during the study period.The amount of nitrogen loss increased with the increase of rainfall during the study period, and the total nitrogen loss showed as follows: M3 ((30.388 ± 2.86) kg · hm-2)> M4 (17.018 ± 1.677) kg · hm-2> M2 ((10.987 ± 1.108) kg · hm-2)> M1 (6.090 ± 1.051) kg · hm-2. Compared with the other models, Runoff and permeable water were the largest during the study period, but the maximum amount of nitrogen loss by surface runoff and permeable water was the highest in M3 mode.Furthermore, in the non-growing seasons, the nitrogen loss was relatively low and the difference between the modes was small, During the growing season, the contents of soluble nitrogen and total nitrogen through the surface runoff and water loss were all in the following four modes: M3> M4> M2> M1. The runoff and infiltration water were all mainly nitrate nitrogen, and the ratio of ammonium nitrogen and soluble total nitrogen to total nitrogen in infiltration water was higher than that of surface runoff.These results showed that the reasonable selection of farming modes, optimization of farming methods, Management provides some basic data for controlling agricultural non-point source pollution in the region.