Experimental Study On Soil Wind Erosion With Conservation Tillage Treatment

Soil wind erosion and desertification are the most important limitations to the sustainabiliry of dryland farming in Northern China. It is urgent to protect the farmland. The conservation tillage system in China has been set up, and many researches have been done with great achievements on conservation tillage technologic and machinery. However, further study is still needed to research on the effects of conservation tillage factors such as residue cover and tillage on wind erosion, to quantify and simulate the compacts of conservation tillage practices on wind erosion. In addition, the equipment used to collect the dust sample in the field is needed to develop. According to the above problems, the research achievements conducted in doctor program are listed as followed.1. Based on the several abroad samplers, the Zhong Nong dust sampler is developed. The features of the sampler are: simple structure, the ability to orientate into winds and to collect samples from various heights at the same location. Moreover, the sampler can operate during wind erosion period unattended. The test of the sampler performance is conducted in wind tunnel.The results show that the sampler satisfies the isokinetical characteristic. The trapping efficiency is about 85.6%. The sampler in its present form is suited to trap the soil particles moving in saltation.2. A field experimental plot equipped with the Zhong Nong samplers and automatic weather station is set up. The plot consists of four treatments such as no-tillage with residue cover(NTC), harrow with residue cover(NTCH), no-tillage without residue cover(NTN) and conventional moldboard plough practice(CK). The systematical experimental study on wind erosion under conservation tillage provides valuable data and feasible methodology.The results show that conservation tillage, which features more residue cover and less soil disturbance, can increase the soil water content by 35.6%, increase the surface roughness by 265.3% and reduce the soil loss of wind erosion by 77.2% compared to CK. Residue cover is more efficient for soil erosion which can reduce the soil erosion by 71.2%, comparably the surface tillage effect is less and only occupies 7%. No-tillage without residue cover can reduce the erosion by 21.6%. The conservation tillage reduces the quantity of the large soil particles moved near the surface by 92.6%, the quantity of dust emission into the atmosphere by 38.6% and the nutrient loss of the field soil.3. Based on the exiting model and the field experiment, a new wind erosion model, which assesses the impacts of conservation tillage practices on wind erosion in China, is set up and calibrated.The preliminary results show that the soil loss values calculated with model are proximally equal to those measured in the field. According to the weather data, the soil water content, surface roughness and tillage management, the field soil loss is calculated hourly under different tillage treatments, which provides information to help in finding of effective measures to reduce winderosion.