Study On Purple Soil Nutrient Loss Under The Artificial Rainfall Simulation Condition

Purple soil moisture,nutrient transfer mechanisms in the three gorges reservoir region are the key focus of soil quality degradation and agricultural non-point source pollutio.Studying on the purple soil nutrients and moisture transfer laws in the area is an important theoretical value and production meaning for the analysis of the mechanism of slope soil quality degradation,the protecting and improving the ecological environment and productivity of dryland agriculture.In this paper,the indoor rainfall simulation experiment was used to study the process of slope water runoff and nutrient transfer characteristics.The main reached conclusions as follows:(1)At different soil water content under the condition of the early runoff,solute concentration and the impact of transfer showed that:For the purple soil,initial soil water content the greater,the time of runoff began earlier,the greater the runoff coefficient.That is,the net flow of rainfall into the more run-off soil erosion on the surface the greater the intensity,the more serious soil erosion, soil erosion and the early changes in water content was similar to a parabola.Purple soil phosphorus and potassium in runoff and corresponding changes in the process of change is similar to the concentration of runoff,there is a "turning point",a turning point in the loss of solute transfer was reduced,and a turning point after the loss of phosphorus and potassium are gradually increasing the volume.It is because at a turning point occurred in the rill erosion,rill erosion slope of phosphorus and potassium increased the amount of the loss,soil erosion as a substantial loss of essential nutrients reasons.(2)Soil conditions in the ground water supply rain strong influence on the slope of solute transfer study:rainfall intensity and soil erosion and nutrient loss in both the relationship between a power function.83.55mm/h accumulated rainfall intensity loss was 34.20mm / h rainfall intensity of the cumulative loss more than doubled.Pre-water the greater the loss of soil nutrients with the amount of runoff greater.The average runoff of phosphorus and clock pre-moisture content and the relationship between parabolic approximations.Water content from 5%to 20%loss of volume of runoff solute doubled.(3)Soil conditions at different slope on the role of the slope show that the transfer of nutrients:in a constant rainfall intensity,the initial runoff 10min,a sharp increase in runoff,followed by a slow increase,the value stabilized.With the steep increase in the degree of increased soil erosion,runoff increased solute concentration,soil erosion on the contribution of runoff increases the concentration of solute.Water-soluble nutrient concentrations in runoff of phosphorus,potassium and bromine ions in the beginning minutes of runoff,runoff in high concentrations,followed by rapid decay.Comparison showed that the application to the characteristics of the power function form of the mathematical model can simulate the purple soil under the conditions of non-saturated concentration of solute runoff processes.Using the power function can also be able to describe the runoff of phosphorus better and potassium changes in the quality process,can not fit but the quality of the initial stage of the process of change.Run-off accumulated loss of potassium bromide and the cumulative loss of runoff volume and the slope was a good linear relationship.Therefore,the lower the nutrient content of soil surface to reduce soil erosion,nutrient runoff is to reduce the loss of one of the important ways.(4)Fertilization on soil runoff and the effects of solute concentration:two fertilizer runoff on the slope do not have an impact in different ways under the conditions of fertilizer runoff generation and the force of the impact of soil surface not large,on soil erosion and nutrient loss affected little.Regardless of the surface mixed layer spray fertilizer or fertilizer,runoff solute concentrations were descending the course of the process of transfer of solute concentration curve from the point of view,the way the process of spraying the surface curve and surface facilities of the process of mixing curve is similar to,but the concentration range than the surface large mixing facilities.Spraying the surface than the surface mixed fertilizer nutrient loss measures the amount of fertilizer,although the mix was more suitable facilities fitting power function,but does not affect the process of change of solute concentration curve,showed power function decay.Surface effects of the initial solute concentration were the key to solute loss,also an important parameter of the simulated runoff solute loss.