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本文以石灰岩地区的棉花作物系统所处流域内(面积为3.8hm~2)径流引起的流失为研究对象,前3年采用传统耕作(CvT)方式,随后3年采用水保耕作(CsT)方式,并对径流中的水量、泥沙量、全N量、NH_4—N,NO_3—N以及可溶性P和颗粒中P的含量进行观测。从1984~1989年在阿拉巴马州北部的石灰岩谷地上进行试验,试区坡度为1%~6%、土壤为暗红色强发育老成土和冲积新成的暗色不饱和始成土。与CvT相比,CsT使流域中年径流次数增加,但是CvT所产生的泥沙量约为CsT的两倍。从晚冬到早春棉花尚不能发挥较大的覆盖作用的时段里,在CvT系统中几场强度较大的暴雨所产生的侵蚀量占侵蚀总量的很大部分。在6年研究期内,径流中NO_3—N的年均舍量都很低,约为1.3~2.2mg/L。冬季黑麦的种植能有效地降低1月到春季施肥期径流中NO_3—N的含量,在4月作物表面施用N、P肥后的较短的一段时间内,径流中NO_3—N和P的含量较高。在研究中,流失掉的P大部分是溶解于水中而不是含于颗粒中,而且CsT中的P的流失量比CvT中要大。但总的说来,从环境保护的角度出发,如果能合理地确定N、P肥的施用量,在棉花种植时CsT比CvT更可行。
In this paper, the loss caused by runoff in the drainage area (3.8hm ~ 2 area) of the cotton crop system in the limestone area was studied. The first three years adopted the traditional tillage (CvT) method and the subsequent three years adopted the soil conservation tillage (CsT) method , And observed the amount of water, sediment, total N, NH_4-N, NO_3-N, soluble P and the content of P in the runoff. From 1984 to 1989, experiments were conducted in the limestone valley in the northern Alabama. The gradient of the test area was 1% -6%. The soil was dark red with strong developed old soil and alluvial dark unsaturated soil. Compared with CvT, CsT increased the number of middle-stream runoff in the basin, but CvT produced about twice as much sediment as CsT. From the late winter to early spring cotton is still not able to play a major role in the coverage of the period, in the CvT system several intense rainfall caused by erosion accounted for a large part of the total erosion. During the 6-year study period, annual average NO3-N in runoff was low, ranging from 1.3 to 2.2 mg / L. The planting of winter rye could effectively reduce the NO3-N content in the runoff from January to spring fertilization. In a short period of time after the crop application of N and P fertilizer in April, NO3-N and P High content. In the study, most of the lost P was dissolved in water rather than contained in the particles, and the amount of P lost in CsT was larger than that in CvT. However, from an environmental protection point of view, CsT is more feasible than CvT when cotton is grown if it is reasonably possible to determine the amount of N, P fertilizer applied.