The Laboratory Experimenal Of Soil Nutrient In The Loess Moving With Surface Runoff During The Simulating Rainfall

Mechanisms and predictions of water and nutrient transport in soils an a slop during rainfall have been played important roles in the research on the degradation of soil quality and the expansion of non-point source pollution in recent years,, which also have been an interdisciplinary field focused in soil erosion, hillslope hydrology, dryland agriculture and related environmental science. The transport mechanisms of soil water and nutrients on slope land are very important both in theory and practice for understanding the principle of soil degradation, environmental protection and increasing the productivity of dryland farming. In this dissertation, the transport of water, nutrients and their distributions along slope land were studied with methods of simulated rainfall experiments. The following results were obtained:1. The influences of rainfall intensity on solute transport in slope land showed that 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. Cumulation drain quantity in 80mm/h rain intensity is two times as much as that of in 40mm/h.; the more the content of antecedent soil moisture, the larger the content of nutrient loss. Both runoff phosphorus and potassium average content and antecedent moisture takes on approximation parabola relationship. The antecedent soil moisture increase from 5% to 20% and nutrient loss increase one times up.2. The influences of slope and slope length on the transport of soil moisture and nutrient on slope land showed that solute concentrations in runoff increased with degree of slope and slope length, and accelerated nutrient loss. Kalium drain quantity and pitch take on very good linear relationship, as well as bromine drain quantity.3. The influences of two types of fertilization on the transport of soil moisture and nutrient on slope land showed that the curve of nutrient loss on condition of sprinkle execute analogy to surface goof execute,but the drain quantity on condition of sprinkle execute is two times lager than surface goof execute.4. The study of vegetation influence on slop nutrient transport shows that vegetation influent soil nutrient greatly. Runoff when soil covered with perennial rye-gras, annual growth rye-grass, Sudan grass, kernel sword respectively decreased 14%, 27%,33%,17% than bare soil under the condition of same vegetational cover and same pitch. nutrient loss on bare land is 3 times lager than 100% degree of coverage. Under condition of same vegetational cover, clay loam soil accumulative loss is less than sand's.5. Using the test data of different rain intensity, pitch,slope length,anticedant soil water and vegetation cover,comparative analysis to solute transport mathematic model described with exponential function formand exponential function shows that the mathematic model characterized by exponential function can better analog the process of loss land's solute concentration.6. At home and abroad description mixed model of soil nutrient loss contain validity mining depth curial issues. Text base mixed model ascertain validity mixing depth shows that The more the rainfall intensity, the more average EDI; There is no evident difference of soil bromine ion's in different slope gradient; Compared with no cover, vegetation cover on land can improve the EDI.