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Study on Soil Erosion of Sloping Farmland in Liaoxi Area

Author: XiaoJiBing
Tutor: SunZhanXiang；JiangChunGuang
School: Chinese Academy of Agricultural Sciences
Course: Utilization of Agricultural Resources
Keywords: Liaoxi area Sloping farmland Millet Sweet potato Soil erosion
CLC: S157
Type: Master's thesis
Year: 2011
Downloads: 110
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Abstract


Rainfall is scarce in Liaoxi area, and more than 70% of rainfall is to form runoff or invalid evaporation, most of the runoff resource not only is wasted, but also causes serious soil erosion. Sloping farmland is source of soil erosion,in order to investigate discipline of agriculture sloping farmland in Liaoxi area,the experiment of runoff observation is studied from 2007 to 2010 in dry farming experimental area in Fuxin in Liaoning Academy of Agricultural Sciences,the problems of soil and water loss and the changes of water and nutrients are monitored through runoff plots.Runoff plots of 5°and 10°are constructed, each grade has three subdistricts, tow subdistricts enforce rotations of millet and sweet potato,the other as the control area.The results show that millet is superior to sweet potato in soil and water conservation through comprehensive analysis,but there is difference in different years owing to different rainfall distribution.Soil erosion,which is serious in wet years, is different in different hydrologic year types. Rainfall is mainly concentrated in the 6-8 months in Fuxin area and soil erosion mainly occurs in this three months especially July in sloping farmland.The accumulated amounts of runoff have a significantly linear positive correlation with erosion quantity under higher rainfall intensity and the both are insignificant power positive correlation under low and middle rainfall intensity. Correlation analysis between soil erosion and rainfall、average rainfall intensity and I30 indicate that the runoff and erosion quantity have a positive correlation with rainfal I、average rainfall intensity and I30. The impact on runoff is rainfall>I30>average rainfall intensity from superior to inferior, the impact on erosion quantity is I30>rainfall>average rainfall intensity. The impact of rainfall on runoff is greater and I30 on erosion quantity is greater. The regression analysis of erosion quantity with rainfall and I30 show that the rainfall has reached a certain intensity and then soil erosion will occur.Soil erosion and vegetation coverage are negatively correlated.The impact of vegetation coverage on erosion is greater than runoff. Antecedent soil moisture and surface runoff are significant positive correlation,but erosion quantity and antecedent soil moisture are insignificant positive correlation. That is that the runoff caused by rainfall which falls on the moist soil is greater than which falls on the dry soil.Rainfall has reached a certain intensity then runoff will occur, the peak value of runoff appears behind of rainfall intensity. The accumulated amounts of runoff and rainfall duration show a quadratic curve.The variance of soil water is affected by rainfall-. runoff and evapotranspiration on dry slope land in semi-arid area of west Liaoning, the variance coefficient of soil moisture decreases with the rise of the soil depth.Soil water decreases and the variance coefficient of soil moisture increases with the rise of the slope. Soil water in agrarian zone is less than grassland and bare slope. The variance coefficient of soil water in agrarian zone is greater than bare slope. The topsoil nutrients after runoff are generally less than before runoff, the nutrients of eroded sediment are greater than those in topsoil before runoff. So the nutrient enrichment in the eroded sediment is obvious, but the enrichment of available P is not obvious.The loss of the nitrogen is greater in several nutrients.Cropoutput decreases with the rise of the slope and output in the lower slope is greater than upper slope.

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CLC: > Agricultural Sciences > Agriculture as the foundation of science > Soil > Soil and Water Conservation
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