Effects of Environment on Winter Rapeseed in Hexi Corridor

Abstract

The soil erosion has been a severe problem in recent years by the co-effect of global warming and human activities in Hexi Corridor in northwest China, where the bio-climatic zone is of arid desert. This region is also developing desertification and one of the most important source areas of sand storms and dust devils in China. Cultivation by traditional ways of spring sown is a part of reason for soil erosion in the region. It is a trend to change the cultivation system of spring sown into that of winter sown for validating the environmental effect. In the paper, we investigated coverage index, wind erosions modulus, soil water content, nutrients, enzymes, and microbe quantity in different types of soil surface, with the treatments of covered with winter rapeseed, winter wheat, and wheat stubble, as well as treatment of spring seeding in Hexi Corridor via trials, wind tunnel experiments, and lab work. The results showed that the soil surface coverage, soil water content, and starting wind speed for the soil growing winter rapeseed were the highest (95%, 11.8%, and 14 m s-1, respectively), the wind erosion modulus was the lowest, which was only 1/25 of that of spring sown. At the height of 20 cm in wind tunnel, the wind transport quantity for the soil growing winter rapeseed was 0.113 g m-2 min-1, as much as 1/206 of the treatment with spring seeding. The weight loss for organic matter, alkali-hydrolyzed N, available P and K, catalase, urease, alkaline phosphatase, invertase, and microbe number per gram dry soil in the treatment with winter rapeseed were 1/6, 1/8, 1/3, 1/2.6, 1/15, 1/64, 1/11, 1/6, and 1/26 of those in the treatment with spring sown, respectively. Therefore, It was suggested that planting winter rapeseed in Hexi Corridor can decrease effectively losses of organic matter,alkali-hydrolyzed N, available P and K, activities of catalase, urease, alkaline phosphatase, invertase, and microbe of soil, at the same time, can remarkably weaken the wind erosion of farmland, the supply of dust storm, and effectively protect ecological en-vironment.