| Predecessors have extensively researched soil moisture on the Loess Plateau, but currently about soil moisture study around Qinghai Lake is less. Gangcha district is one of the main grassland and main sites of runoff round the Lake in Qinghai Province, The region has characteristics with poor natural conditions and highland continental climate which rainfall is less, Water is a major constraint factor to local vegetation growth.In this view, According to the study of soil moisture, it reveals that it's important theoretical significance of the profile distribution of soil moisture, variation regular and suitable vegetation for the development, provides the scientific basis for the surrounding ecological environment in Qinghai Lake.Based on field research in Gangcha County, two towns selected accomplish sample sites of soil moisture experiment.We respectively execute soil moisture,particle size measurement and analysis on 56 profiles of soil samples, discusse some questions of changes characteristics of soil moisture and causes, and gives proposals to the local agricultural development and production.Mainly obtain the following understanding:(1)There is more precipitation in 2009,which is a wet year in this region.The maximum depth of bulk water in remaining sampling sites is no more than 60cm,except in rapeseed is up to 130cm for irrigation.(2) It's different of soil moisture on distinct vegetation in Gangcha,but identical of reduce with depth.Soil dry layer occurs at the depth of 90cm on irrigated grass sampling site at Shaliuhe Town,and the degree of drying is relatively serious;the average of soil moisture in rapeseed is greater than 12%;Soil dry layer occurs at the depth of 70cm on ranch sampling site, dry layer here is less shallow than at artificial vegetation zone, dry layers both develop at artificial vegetation area and the farm,and the degree of development severe with the increasing depth.This also shows that the local rainfall does not fully meet the needs of growth and development of natural grass.dry layer appears in the depth of 80cm at Jiermeng Village, and more serious below 100cm.(3)Composition of grain size with depth has a significant variation discipline, sand content increased in lower layer.In profiles at Shaliuhe Town, composition of particle size is mainly of coarse silt,the highest content is more than 50%;.in profiles at Jiermeng Village, composition of particle size is mainly of coarse silt size, following in the 100cm dominated by fine sand, An inverse relationship is showed between water content and particle size, That is more coarse soil particle size, the lower soil moisture content.(4)Soil dry layer common develops in the region, It should be to mainly develop drought-resistant grass and other crops that consume less water. Rape planting of an extensive site is the most important cash crops in Gangcha region,which should be planted close to the river, irrigation drains to facilitate irrigation of the plain. But the water consumption of rape is high, in order to reduce excessive water consumption and reduction of river water volume into the lake, it should be moderate limit the rape cultivation area, while promoting water-saving irrigation measures and to increase the protection of water conservation efforts.(5)Strengthen water conservancy infrastructure, expansion of irrigated site,so as to make up for lack of precipitation, Better get to meet the needs of plant growth.Adhere to grassland restoration strategies, scientificly and reasonably determined carrying capacity according to the number of pasture stocking rate to achieve appropriate and sustainable development. |
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