Mechanism And Simulation Of Nutrient Transport On Loess Slope Land During Rainfall

Mechanisms and predictions of water and nutrient transport in soils on a slope during rainfall have been played important roles in the research on the degradation of soil quality and the expansion of non-point source pollutions in recent years, which also have been an interdisciplinary field focused in soil erosion, hillslope hydrology, dryland agriculture and related environmental sciences, so investigation of the mechanism and model of soil water and nutrient transport for effectively predicting and preventing soil nutrient loss at intensively-eroded area on the loess section is of important significance to environment protection and management of water and nutrient on slope land.Selecting non-adsorbed NO3--N or Br-, adsorbed phosphorus (P) and potassium (K) as materials of study, this paper has discussed the influence of several factors on the migration mechanism of soil, water and nutrient on slope land by the methods of simulated rainfall in both the indoor soil boxes and the field plots. The intrinsic mechanism of the release and migration of soil solute transport transport to runoff during rainfall was discovered, the characteristics of soil and nutrient loss in response to various factors influencing it were illustrated, and the model to simulate the process of soil solute transport to runoff was developed, which would serve valuable scientific data for reducing and preventing soil, water and nutrient loss from slope lands and evaluating the status of non-point source pollution in the loess region.The main conclusions are as follows:1. The results of experiments in laboratory showed that soil textures, rainfall intensities and surface slope gradients significantly affected the solute transport on slope. Transient change curves of P and K concentrations in runoff decreased as a power function on clay loam soil slope land, while the curve of P concentrations in runoff was described by a parabolic function, which is resulted from the accelerated nutrient loss caused by rill erosion on sandy soil slope. The relations of rainfall intensity and the soil erosion amount and that of rainfall intensity and nutrient loss can be both described by exponential functions. Solute concentrations in runoff increased with degree of a slope, and soil erosion accelerated nutrient loss.2. The influences of soil bulk density and antecedent soil water content on the transport of soil...