Characteristics Of Solute Loss And Distribution In Red Soil Slope Under Flushing Conditions

The red soil hilly region of southern China is one of the most serious soil erosion areas in our country. Soil erosion and nutrient transfer on sloping land are the important reasons for soil degradation and water non-point source pollution in surrounding areas, and it is also a hot issue in the research of agricultural non-point source pollution. Hydrological condition of sloping land is one of the key factors that affect soil erosion and solute transport. The degree of soil erosion and the amount of solute transport are closely related to the condition of surface runoff. Therefore, it has important scientific significance to discussing on the mechanism of soil solute transport on red soil sloping land, revealing the intrinsic relationship of oil hydrology, soil erosion and solute transport on sloping land, and the effect of slope position distribution on sloping land of nitrogen and phosphorus. Also it has a great realistic guiding significance to control soil erosion on red soil sloping land, protect agricultural ecological environment, ensure the efficient utilization and management of soil and water resources.We take red soil sloping land of southern China as the main object of this study. Through upslope scouring soil bin and observing the nutrient distribution of runoff plot slope surface, we analyzed the effect of red soil slope surface solute transport characteristics to the flow from upslope, the slope gradient and other factors under the the condition of erosion, and studied the effect of soil nitrogen and phosphorus distribution on slope position to typical planting modes on hilly slope of southern China under the condition of natural rainfall. The main results are as follows:1. Under the condition of constant current flow, the initial slope runoff time was advanced with the increase of slope gradient; Runoff accumulation was decreased with the increase of slope gradient; Sediment erosion was increased with the increase of slope gradient, but the runoff and sediment rate were not showed a monotonic relations.2. The red soil runoff of bromide ion on slope surface loss was increased with the increase of slope gradient; The soil runoff of bromide ion loss has a negative correlation with the increase of slope gradient, when the slope gradient was 15°, the mass concentration of bromide ion became larger, namely there have a critical slope gradient of bromine ion erosion in red soil may be between 10-15°; The bromide ions retention in the soil increased with the increase of the slope gradient.3. Under the condition of constant slope gradient, the greater the flow from upslope, the greater the surface runoff and subsurface flow; Sediment erosion was increased at first and then decay with the continuation of runoff time; Sediment erosion was increased with the increase of the flow from upslope, the flow from upslope and sediment erosion were both increased, and the flow, the amount of sediment and runoff have a good linear relationship.4. Initial runoff of bromide ion concentration is higher, then the fluctuate decays quickly to zero. The interflow bromide ion concentration showed a incremental change of power function with the continuation of time, and after a period of time tends to be stable. With the flow from upslope increased, the erosion of non adsorbed solute increased.5.The representation of soil moisture content in different slope were downhill slope>uphill slope>middle slope. The soil of various plots presented acidic, pH of middle slope was higher than the other two types slope, and the difference was not significant. The soil nutrient contents in different slopes were mainly collected in the downhill slope, so the soil nutrient content here is higher than the other two types slope. Except the underlying surface was bare area, the content of ammonia nitrogen and alkali solution nitrogen in soil of the rest plots basic showed a trend of "downhill slope>middle slope>uphill slope". Downhill slope has the lowest rapid available phosphorus content in each layer soil of different underlying surface, and it is similar to the variation of ammonia nitrogen. The content of available potassium showed a trend of "downhill slope>middle slope>uphill slope". The total nutrient in bare land was lower than the other three crops (corn, ramie, pasture) in soil.