Study On Conservative Tillage Models For Controlling Wind Erosion At Transition Zone Between Agriculture And Pasture Areas In The North Foot Region Of Yinshan Mountain

In the past few years, the dust storm was paid great attention to by population, because it occurred more frequently than before and impacted not only the North China but also the south of the Changjiang Valley, even Korea,Japan and the Pacific. The North Foot Region of Yinshan Mountain, locating the middle of transition zone between agriculture and pasture areas where is the ecologic protective screen for the North, is the main strengthened dust source zone for upper drift of the North China and Beijing. If the desertification could not be controlled in the area, it will continue to extend southward, as a result,the dust over the North China will be difficult to control in the spring and the economic losing caused by dust storm will be incalculable. Based on the achievements obtained and according to the adaptability rules of ecology, the main factors caused the wind erosion were studied and the present desertification situation and the undesirable eco-economy consequences caused by wind erosion was researched with methods including field experiments, field investigation and system analysis in the paper. The basic of controlling desertification was improvement of the ecologic environment and the requirement of reconstruction at transition zone between agriculture and pasture areas with practicing of the conservative tillage technique suitably. So in order to achieve the way to deal with wind erosion and to reconstruct the North Foot Region of Yinshan Mountain ecologically, according to the topography, landform, climate and the planting structure of different sub-regions, different conservative tillage models of strip intercropping have been tested to determine the reasonable strip width of crops, grass and shrub for controlling wind erosion and conserving the soil moisture in farmlands and grasslands in winter and spring. The results showed: The climatic factors were suitable for wind erosion in the North foot Region of Yinshan Mountain and the annual average climatic erosivity is 154.5, which is over the serious degree (C≥100). For the seasons, the spring is the most serious with climatic erosivity of 80.3, then the following seasons are winter (38.7), summer (18.9) and autumn (16.6). At the hilly region of the south part of the North Foot of Yinshan Mountain, the model of ecological reconstruction with a hill as cell can be generalized as "the top with grass, the middle with contour fields, and the gully full planting trees". The contour fields could increase the roughness effectively than the sloping fields. At the same time, wind velocity at 5cm above ground was decreased 42% and soil erosion was reduced 30%. In the south part of the North Foot Region of Yinshan Mountain, with annual precipitation of 350 to 400mm and deep soil layers, most fields are cultivated for crops. Intercropping strips of row crop like wheat and hole sowed crop like potato, keeping stubble after the growing season, were used for the experiments of controlling wind erosion. Compared with traditional model of plowing in Autumn, the fields with stubble of intercropping strip model had obvious effects . The wind velocity at 5cm above ground was decreased 53.2%, the soil erosion was averagely reduced 72.3%, soil grains over 0.01mm were reduced 29%, main nutrients were increased 11.8%~72.9%. soil water content was increased averagely 55.1% in the layer from 0cm to 30cm in spring and was still preserved during the whole growth period. Furthermore, intercropping strips of wheat and potato with stubble could improve the yields for marginal utility. Compared with single cropping , the wheat yield could increase 0.8%~25.1%, the potato yield increases 4.3%~11.6% and the utilizing ratio of land improved 11.2%. In the middle part of the North Foot Region of Yinshan Mountain, the annual precipitation is only 280 to 350mm, wind erosion and desertification are both quite serious. Reclamation should be controlled and farmers are encouraged to grow grass. The suitable model appears intercropping of grass and crops. Compared with the traditional model of plowing in autumn, the model had effects on increasing the roughness, decreasing wind velocity at 5cm above ground about 31.6%, reducing soil erosion by 79.4%, slowing down the soil surface coarseness with only 2.5% of the gravel over 1mm in the winter bare field, and improving the biomass with 3773kg/hm2 which was 5.7 times than that in the natural grassland. In north part of the North Foot Region of Yinshan Mountain, the annual precipitation is under 280mm, yield of dryland farming is very low, disasters and wind erosion are very serious. So cultivation should be stopped except the river valleys in order to recover rangeland. Because the restoring process of natural vegetation is very slow, the shrub and grass should be planted artificially at some region. Intercropping types of shrub and grass was tested. In the model, the roughness of grass belt was 0.95cm, soil erosion was reduced averagely 75.0% comparing with the degeneration grassland, which was higher than that of the single growth grassland. And biomass was respectively 1.2 times, 2.5 times and 5.3 times of the single growth grassland with fence, natural grassland with fence and degenerated grassland. At last, based on the theory of healthy ecology system, in order to achieve the duple objects maximizing output and minimizing runoff and wind erosion, the strategy of reconstructing should adjusting measures to local conditions and developing reasonably for optimizing the land use in the North Foot Region of Yinshan Mountain.