Soil Erosion Characteristics And Control Effects On Nitrogen Loss Of Three Types Soils Under Simulated Rainfall

Rainfall is not only the main power of soil erosion, but also is the basis of runoff. The action that large amount of nutrient is transferred by runoff changes the structure and texture of soil, and also leads the re-allocation of nutrient. Soil erosion and loss of nutrient which are caused by rainfall are the most serious environmental problems, and the core of the research on degradation of soil quality and the agricultural non-point pollution, and also have been an interdisciplinary field focused in soil, hydrology and environment.Focused on the problem of soil erosion and loss of nutrient in restricting agricultural development and worsening ecological environment, simulated rainfall experiments were conducted to research soil erosion characteristics and controlling effects of controlled release urea coated by polymer on N losses in the cinnamon soil, brown soil and red soil, analyze the runoff, sediment and nutrient losses in the three types of soil, clarify the effects of controlled release urea coated by polymer, which provides scientific theoretical and practical basis for reducing nutrient losses and nitrogen loss in especial and has important significance in protecting ecological environment. And the main results are as follows:1. The loss amount of total nitrogen and available phosphorus and potassium in soil carried by runoff accounted for the loss of total amount 77.27%~99.79% in the three types of soil under the conditions of rainfall simulation. Runoff was the main driving force of slope soil erosion.2. The runoff, sediment yield and the total loss of NPK of the cinnamon soil were all the least in the three types of soil under the conditions of rainfall simulation. Compared with the cinnamon soil, the amount of nutrient losses in the brown soil increased by 4.70%~41.01%.The runoff and sediment yield of the red soil was the biggest, the amount of nutrient losses was 1.20~1.65 times comparing with the brown soil. Different types and properties is the fundamental reason in the nutrient losses of different soils.3. The total nitrogen and available phosphorus and potassium in the three types of soil accumulated in different degree in different parts of the surface soil of the slope, leached in different degree in the whole soil box, which was different obviously in space. There was a small change of soil mechanical composition, the amount of clay decreased by 2.11%~4.79%, however, increased by 1.18%~2.12% in sand.4. Controlled release urea coated by polymer has great controlled release ability. With the continuation of rainfall simulation, it can postpone the peak of loss of NH4+-N, NO3--N soil runoff, compared to common urea, the loss of NH4+-N, NO3--N and total N of soil, to a great extent, can be decreased by 30.4%, 30.8%, 7.9% respectively. The extension and utilization of the controlled release urea coated by polymer is one of effective measures to prevent agricultural non-point source pollution.