| As the largest plateau wetland in China in Northwest Sichuan, Ruoergai region is very uneven in spatial and temporal distribution due to the restriction of the groundwater resources by climate conditions, coupled with man-made overgrazing in recent years that causes a larger area of desertification in the original wetland. For the serious desertification problem in Northwest Sichuan, the research work has been carried out on the measures for desertification control. Water resources that the plants rely on for survival are mostly supplied by the vadose zone moisture, so the reasonable and effective use of soil water in vadose zone is the key to restore the natural vegetation, optimize the ecological environment and realize the sustainable development of animal husbandry in desertification areas of Northwest Sichuan. This study aims to analyze characteristics of the changes in space distribution of soil water in the wetland of Northwest Sichuan, determine the factors influencing the distribution of soil water in vadose zone, put forward reasonable water content suitable for grass, and study if the micronutrient fertilizer technology plays a role in promoting the growth if plants with the help of the new micronutrient fertilizer technology, providing a certain theoretical basis for the reconstruction of ecological environment by combination of the hydrological geology and ecology together for rational use of groundwater resources and vegetation restoration in a faster and better way in the desertification areas of Northwest Sichuan.In this paper, with field tests in the study area, soil moisture data is collected from the bare land and the land covered with grass with micro field cultivation tests in the bare land. According to the study of the factors affecting the distribution characteristics based on the moisture data collected, we find that:(1) The soil water content in vadose zone is largely affected by geography. In the same slope direction, water content is the largest at the base of slope, followed by the midslope with the lowest at the slop top. There are great differences for slopes in different directions, compared with the leeward side, the windward side of the slope has much less water.(2) The different climate is also a key factor restricting the water content in vadose zone. Studies show that a heavy rain has the greatest impact on the water content rate in the soil surface of 0 ~ 5cm with an increase of the water content over 5 times after the rain, while the water content in the in the soil 5~45cm is increased slightly. The change of seasonal temperature conditions also has a great impact on the soil water content, the water content in May and September is 3 times as much as that in July and August.(3) The roots of supergene vegetation can retain the water in vadose zone, making the water content in the soil near the roots larger than that in the surrounding area.(4) Through measurement of water content in soil of 0 ~ 50 cm, we find the water content suitable for grass needs to reach 5% at least.(5) The range of the available water of grass area was 10.4%~56.8%,the range of the available water of bare area was 8.1%~43.5%.In this study, in grass cultivation by introduction of micronutrient fertilizer technology, we find that:(1) The germination percentage of the seeds soaked with the ionic titanium solution at appropriate concentration is 6 percent higher than that treated by other methods on average.(2) According to samples of grass cultivated in the micro field, the grass with soaking of seeds is significantly different from that without soaking of seeds in the form, the former is 3.4cm longer on average.(3) The ways of plant cultivation discussed in this paper include sowing in line and by scattering, and according to the test results, the plants sowed in line are 2.3cm longer on average than those sowed by scattering.The above results have important theoretic and practical meaning for scientific management of supergene eco-environment as well as reasonable development and use of groundwater in the desertification areas of Northwest Sichuan. |
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