Soil Water Dynamic Evolvement And High Efficiency Utilization Under The Influence Of Human Activity

Water was very important for human to live, and was security of the socio-economic development. With the development of industrial and social progress, the demand of fresh water resources increased seriously. In most places, surface water and shallow groundwater were polluted, which intensified shortage of freshwater resources. In Hebei province, agricultural water accounted for about 83.5 percent of the total consumption of water. It was the key problem to easy the shortage of freshwater resources. In the present, exploiting new fresh water resource and implementing water conservation for agriculture was one of the fundamental ways to resolve conflict between supply and demand of water for agriculture. Straw mulch was one of the most widely and convenient ways to solve the problem. Studying the impact of straw mulch on the dynamics of soil water and efficient use of soil water and finding the change in law about soil water transport was the scientific reference of utilizing reasonably soil water and development of precision agriculture crop irrigation system, in order to solve China's shortage of water for agriculture to provide scientific information.The testing had been working since 5 years ago in the Luancheng testing of the Center for Agricultural Resources Research of the Chinese Academy of Sciences, in Shijiazhuang city, Hebei province. The testing included straw mulch test and comparative test, which monitored the change of soil water.The difference of system between the two pilots was analyzed by the cover pre-and post-soil water data. The aim of this paper was that studying the impact of straw mulch on evolution of the law of the soil water dynamics, finding out the soil water resource how to go and how to come, analyzing the impact of straw mulch on soil water resource, proposing and using potential usable soil water parameter, the actual flood storage capacity,storage coefficient, the effective utilization rate of soil water and so on to evaluate and effective utilization of soil water and the impact of straw mulch on which, then giving the precise irrigation system.It showed that the impact of straw mulch on the soil water dynamics associating with rainfall, climate, crop growth, and soil depth and soil water level of the initial moisture content. The impact on the soil moisture was very obviously in the depth between Ocm and -180cm, and with the depth increasing, the impact was weakened, however, the impact in the depth between -180cm and -340cm was basically not subject to surface conditions. During the straw mulch test, in the drought period the level of soil water was significantly higher in straw mulch point than the comparative test point, while in the wetter period only in -10cm depth the level of soil water was slightly higher, others were same. According to the soil water potential data, some law could be found which was that in the dry period the straw mulch was helpful for shallow depth soil to keep soil water for longer, while in the wet period the impact of straw mulch on soil water changing was very small. In addition, the straw mulch could prevent irrigation and rainfall from infiltrating.The surface evaporation, soil water infiltration, storage capacity, the potential usable soil water were affected seriously by straw mulch. The evaporation in bare mainly, the straw mulch could prevent soil water from transporting to air, while the evaporation was accelerated when in transpiration primarily. In dry period straw mulch advanced soil water in depth penetrating while in wet period the infiltration velocity was bigger than the corresponding point. The soil storage and potential soil water of straw mulch were much higher than another point. Storage capacity of the soil was relate to the initial soil moisture and the speed of soil water utilization, and was very big in study area. However, the effective utilization of soil moisture was very low, about 50 percent. Medium-term of growth crops, the effective utilization was lightly higher than the comparative test points. The rainfall (greater than 20 mm) or irrigation reduced the effective utilization rate of soil moisture, rainfall and small (less than 20 mm) to promote the effective absorption of soil water.According to the above study, the irrigation frequency was adjusted to five times from three times, the quantity of each irrigation was 20mm while 60mm ago, then about 90mm water could be saved, the effective utilization of soil water was improved by 15 percent. The irrigation system should be amended by crop production, and then the perfect and high-yielding system could be made to remit the conflict between supply and demand for agriculture water.