| As a foodstuff producing area, Phaeozem region of northeast China becomes a important production base of marketable grain along with the transformation of grain liquidity structures in China, which means the height of the integrated production will be related to the stability of commodity grain supply. The natural fertility of northeast black soil area in China has been declined year by year, the soil layer degradation such as thinning, top soil going harder is severe. Black soil erosion management become an important issue. Features of the erosion of slope cropland in northeast China is remarkable, as for the long and gentle slope, different ridge tillage can make different influence of the surface runoff. Concentrated rainfall in the farming season can result in the top soil and natural fertility loss under the washing of surface runoff. The corn straw mulching can impedance control the erosion of slope cropland soil from the source, both decrease the pollution from burning straw, and it also makes a great contribution to soil and water conservation of slope cropland. Also, the operation of whole straw mulching is simple, can easily accept by farmers. This research draw conclusions through the observation of the “Different Ridge Direction of Slope Runoff Plot” and the “Whole Straw Mulching Standard Runoff Plot”, and the results showed that:(1)Under the same slope, the interception percentage of surface runoff by slope-cross ridge tillage can reach 50%. According to the slope-along ridge tillage, the mean lost thickness of the side soil layer by ridge is 18.8mm of Chinese cabbage plot, which is 20.92 mm with slope-cross ridge tillage; and its sedimentation in field ditch has been 42.80 mm average with slope-along ridge tillage, which is 35.13 mm with slope-cross ridge tillage. As for soybean, difference of side soil loss by ridge between slope-cross and slope-along ridge tillage is not big, but the sedimentation in field ditch slope-cross is more than slope-along ridge tillage. The loss of side soil by ridge with growing maize, slope-cross is worse than slope-along ridge tillage. Under the condition of different crops, slope-cross shows a good in held the runoff and sediment, but also have large differences among different crops. Besides cabbage- slope-along plot, others show good in held the runoff and sediment.(2)Through analyzing the runoff volume and sediment content of runoff in different slope plot, found that: the effect of flow-decrease is remarkable according to the whole straw mulching in different development stages of maize; as maize growth, the effect of flow-decrease trend to increase. Whole straw mulching effect in decreasing the runoff is tend to increase with the increasing rainfall intensity. However, when rainfall intensity achieve a certain intensity, the effect of decreasing runoff and sediment with whole straw mulching is unsatisfactory in 9°slope; overall, the effect of decreasing runoff and sediment with whole straw mulching on black soil is remarkable, but as cultivated fixed of year, the effect had slightly reduced.(3)Through to the analysis of the N, P nutrient content of runoff sediment under 3 different slope standard runoff plot, found that: the transform modulus of available N under whole straw mulching on 3°, 6°, 9° slope is 20%, 27.5%, 11.0% to the normal tillage, which decreasing 80%, 75.5% and 89%. The transform modulus of total N under whole straw mulching on 3°, 6°, 9° slope is 20.3%, 35.8%, 16.5% to the normal tillage, which decreasing 79.7%, 64.2% and 83.5%. The transform modulus of available P under whole straw mulching on 3°, 6°, 9° slope is 33.3%, 18.8%, 9.1% to the normal tillage, which decreasing 66.7%, 81.2% and 90.9%. The transform modulus of total P under whole straw mulching on 3°, 6°, 9° slope is 19.4%, 34.1%, 7.8% to the normal tillage, which decreasing 80.6%, 65.9% and 92.2%... |
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