N降雨侵蚀因子和植被类型及覆盖度对坡耕地土壤侵蚀的影响.

In order to discuss the effect of rainfall and vegetion on soil erosion of sloping farmland in cimiamon soil region in western Liaoning, the experiment was earned out under natiual rainfall on artificial slope nmoff plots from 2006 to 2010. The nmoff plots with an intei-val of 1 m were designed according to the 20-year standard and each area was 60 m2 Slope factor was set as 5° and 10° respectively. Among 3 nmofi'plots built under the same slope, 2 plots were practiced by millet-sweet potato rotation, and another nmoff plot was set as the control, which was the natmal hillside field in 2006-2007 and bare slope (coverage <5%) in 2008-2010. Millet and sweet potato were planted as test crops by contour tillage and row spacing was 50 cm. The result showed that soil erosion in the sloping familand mainly occmred between Jiuie and August, paiticularly in July. The siuface nmoff and erosion amoimt increased in accordance with the increasing of giadient and the effect of slope on erosion amount was greater than nmoff with the slope increasing. When rainfall reached a ceitain intensity, soil erosion would occm*. The experiment also showed that the siuface nmoff and erosion amount on sweet potato field had significantly positive relations with the rainfall (P<0.01 for nmoff. P<0.05 for erosion amount), the maximum 30-niinute rainfall intensity (P<0.01), the rainfall erosivity (which was the product of the former 2 factors) (P<0.01), and the product of rainfall and average rainfall intensity (P<0.01); the nmoff on bare soil field had significantly positive relations with the rainfall (P<0.01 and P<0.05 on 5° and 10° bare soil field, respectively), and the rainfall erosivity (P<0.01): the erosion amount had significantly positive relations with the maximum 30-niinute rainfall intensity (P<0.05 andP<0.01 on 5° and 10° bare soil field, respectively), and the rainfall erosivity (P<0.01), but had not positively significant relation with rainfall. The siuface nmoff and erosion amount were mostly affected by the precipitation and the maximum 30-minute rainfall intensity respectively tluougli regiession analysis and the both had not positively significant relation with average rainfall intensity on sweet potato and bare soil field. Erosion amoimt had a relation of power fiinction and a significantly positive conelation with siuface nmofi' under medium and higlier rainfall intensity (P<0.01). The siuface nmoff and erosion amount on sweet potato field had a significantly negative exponential fimetion relation (P<0.05). The amoimt of soil erosion on sweet potato field was the largest, the following was millet field and that of wild glass giound was the least. Multi variance regiession analysis revealed that the factors impacting the amoimt of soil erosion from high to low were siuface nmoff. rainfall erosivity, and vegetation coverage, and the effects of rainfall erosivity and vegetation coverage on soil erosion increased with the slope increasing. Vegetation cover was especially impoitant to protect against soil erosion on sloping farmland in western Liaoning, and crop management would be paid more attention with the increasing of gradient. The effects of different factors such as rainfall and crop varieties on soil erosion on sloping familand were preliminarily known after the 5-year experiment in tliis paper. The research provides theoretical basis and teclmical support for the effective prevention and treatment of soil erosion in the region. [ABSTRACT FROM AUTHOR]