河西走廊种植冬油菜的环境效应

设置田间试验及风洞试验, 对河西走廊的冬油菜、冬小麦、麦茬和春播4种地表类型的有关指标的测试分析表明, 冬油菜地表的覆盖度、土壤含水量、起动风速均最高, 分别达95%、11.8%和14 m s^-1；其风蚀模数最小, 仅为春播处理的1/25；其距地面20 cm高的气流层内, 风蚀物输送量为0.113 g m^-2 min^-1, 是春播地的1/206；其地表1 g风干土的土壤有机质、碱解N、速效P、速效K、土壤过氧化氢酶、脲酶、碱性磷酸酶、转化酶活性和微生物数量等的损失量分别是春播地的1/29、1/8、1/2.6、1/15、1/42、1/11、1/6.5、1/6和1/27。可见, 冬油菜在河西走廊等北方地区推广种植, 能有效减少土壤有机质、速效N、速效P、速效K以及酶活性和微生物等的损耗, 显著减弱农田地表风蚀沙漠化发展, 抑制沙尘暴的尘源供给, 增进生态环境保护和社会经济效益。

Effects of Environment on Winter Rapeseed in Hexi Corridor

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 China, where the bio-climatic zone is of arid desert. The 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, 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, starting wind speed for the soil growing winter rapeseed were the highest (95%, 11.8%, 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 g 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 environment.