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Effect of Near-Surface Soil Hydrological Conditions on Soil Erosion and Nutrient Losses at Hillslopes

Author: CuiYanPing
Tutor: ZhengFenLi
School: Northwest University of Science and Technology
Course: Soil and Water Conservation and Desertification Combating
Keywords: Soil hydrological conditions Purple soil Red Soil Soil runoff Soil Erosion N and P nutrient loss
CLC: S157.1
Type: Master's thesis
Year: 2009
Downloads: 127
Quote: 1
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Abstract


Study near-surface soil hydrological conditions on soil erosion and loss of nitrogen and phosphorus nutrients not only to deepen the understanding of the process of soil erosion and nutrient loss migration mechanism, but also provide important scientific basis for agricultural nonpoint source pollution control. This study for the purple soil and red soil hilly region slope farmland soil erosion prevention and the urgent need for agricultural non-point source pollution control, artificial simulated rainfall experiment and analysis of the combination of research methods to study the near-surface soil hydrological conditions on the purple soil and red soil slope soil erosion and nitrogen and phosphorus nutrient loss process, revealing the red soil slope under different fertilizer types and different hydrological conditions of nitrogen and phosphorus nutrients in the migration process. The main conclusions are as follows: 1. Clarify the impact of the near-surface soil hydrological conditions on the purple soil and red soil soil erosion process. For two soil types, the near-surface soil hydrological conditions have an important impact on soil erosion process. Purple soil slope, soil moisture saturated soil runoff of soil erosion under rainfall conditions are freedom infiltration under the conditions of 1.6 to 1.8 and 2.7 to 3.5 times. For red soil slope, soil moisture saturated soil runoff rainfall erosion freedom infiltration under the conditions of 1.5 and 2.3 times, respectively. Comparative analysis of purple soil slope under the same test conditions, and the difference of the red earth soil erosion process. In the test conditions of 60 mm / h rainfall intensity, 15 ° slope hydrological conditions and freedom infiltration, runoff purple soil slope is significantly larger than the red soil slope, but the amount of red soil slope erosion purple soil slope 1.1 times. Under the same conditions of rainfall and the same slope, when the hydrological conditions of the near-surface soil infiltration into soil water saturation by the Liberal red soil slope with purple soil slope erosion intensity is basically the same. Soil hydrological conditions near the ground into the soil runoff, in the same rainfall and slope conditions, the purple soil slope runoff is 83% of the red soil slope, erosion of purple soil slope red soil slope of 1.2 times. Reflect subsurface flow the purple slope erosion process is greater than the red soil slope. 3 purple soil under different near-surface soil hydrological conditions and the loss of red soil slope soil nitrogen and phosphorus nutrients law. Compared to the same freedom infiltration conditions under saturated soil moisture, soil runoff and soil runoff surface under rainfall conditions to runoff in NO 3 -N and PO 4 -P concentration its loss are significantly increased. Purple soil slope, soil runoff and subsurface flow under saturated conditions of rainfall and soil moisture, surface runoff in the NO 3 -N loss of freedom infiltration conditions from 192 to 277,100 to 114 and 27 to 39 times. Soil runoff surface runoff rainfall and soil moisture saturation conditions in PO 4 -P loss of freedom infiltration conditions 1.5 to 1.7 and 1.3 times respectively. For red soil slope, soil runoff and soil runoff surface runoff in NO 3 -N loss under the conditions of rainfall and soil moisture saturation free infiltration conditions from 143 to 210,323 to 355, and 60, respectively ~ 67-fold. Soil runoff and soil runoff rainfall surface runoff in PO 4 -P's loss of freedom infiltration conditions 1.1 to 4.9 and 2.5 to 3.7 times, respectively. For the two test soil, hydrological conditions on the three near-surface soil nitrogen and phosphorus nutrients with the loss of eroded sediment showed the same law, that soil runoff of rainfall and soil moisture saturation conditions eroded sediment in the of NO 3 < / sub>-N and PO of 4 -P content and loss are significantly greater than the free infiltration conditions. The comparative analysis of the differences in the purple soil slope under the same hydrological conditions and the red soil slope nutrient loss. Infiltration conditions under freedom, the purple soil slope runoff in NO 3 -N and PO 4 -P loss of red soil slope is greater than the loss of the former are the latter from 2.0 to 2.1 and 1.1 to 1.9 times. Soil moisture saturation conditions purple soil slope runoff NO 3 -N loss of the amount of red soil slope is basically the same. Purple Slope surface runoff, subsurface flow conditions in NO 3 -N loss is 1.5 to 3.1 times that of the red soil slope, soil runoff purple soil slope runoff nitrogen loss in the red soil slope. Runoff phosphorus losses from low fat level under the conditions of soil moisture saturated soil runoff conditions purple soil slope runoff PO 4 -P loss of the amount of red soil slope of 2.1 and 2.0 times, respectively; under conditions of high fertilizer levels in the purple soil slope runoff PO 4 -P loss of red soil slope were less than the loss of the latter are 1.4 and 4.3 times of the former. Purple soil and red soil the hillslope erosion sediment NO 3 -N loss was no significant difference; under the free infiltration and soil moisture saturation two kinds hydrological conditions, but freedom infiltration and soil water saturation conditions PO 4 -P loss in purple soil slope erosion sediment less than the red soil slope, which is 1.1 to 3.3 and 1.5 to 2.0 times of the former. 5 discusses the reasons for the near-surface hydrological conditions on soil erosion and nutrient loss. Free infiltration conditions, mainly due to the impact of the free infiltration force, part of the soil surface nutrients leached into the subsurface soil profile with rainfall infiltration, soil nutrient loss with runoff and sediment erosion reduction. Subsurface flow conditions, not only the nutrients in the soil is soil runoff carries migrated into the soil surface, the loss of bond strength between the soil particles and soil runoff formation, The soil erodibility increase, resulting in increased slope soil erosion intensity thus soil nitrogen, phosphorus nutrients with increased runoff and erosion sediment loss. Specific performance soil runoff conditions 0 ~ 2 cm of the soil surface soil NO 3 -N highest content of 1.2 to 1.3 times the subsurface soil; freedom infiltration conditions, sub- the highest content of surface NO 3 -N, is 4.0 to 9.3 times of the topsoil. 6 reveals the loss of the red soil slope under different fertilizer types and different hydrological conditions of nitrogen and phosphorus nutrients law. Surface runoff and eroded sediment NO 3 -N concentration and its loss applied KNO 3 analytically pure and applied urea under the conditions of a significant difference. Soil runoff and soil runoff rainfall conditions, when applied KNO 3 runoff in NO 3 -N loss when analytical grade urea application from 1.8 to 2.0 and 1.9 times. But applied KNO 3 analytical grade sediment erosion NO 3 -N loss is less than the applied urea NO 3 -N The loss amount. Similarly, surface runoff and eroded sediment the PO 4 -P loss in facilities K2HPO in 4 analytical grade and superphosphate conditions were significantly different, that is, under the freedom infiltration, soil runoff and soil runoff rainfall conditions when facilities K2HPO 4 analytical grade surface runoff in PO 4 -P loss superphosphate PO 4 -P loss of 1.9 ~ 2.6,1.9 ~ 3.6 and 1.5 to 2.8 times; the eroded sediment PO 4 -P loss performance under the conditions of the two fertilization The law of the same performance with eroded sediment NO 3 -N loss.

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CLC: > Agricultural Sciences > Agriculture as the foundation of science > Soil > Soil and Water Conservation > The causes and prevention of soil erosion
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