Impact Of Buried Depth Of Phreatic Water Under Straw Returning For Soil Moisture And Evaporation

China’s coastal shallow groundwater depth is very shallow areas of non-agricultural water consumption increased dramatically, the contradiction between supply and demand of water resources will become more acute.More and more attention has been paid so efficient use of shallow groundwater. The non-agricultural water consumption increases dramatically in China’s coastal area where groundwater depth is very shallow. And the contradiction between supply and demand of water resources will become more and more acute. So use of shallow groundwater efficiently has been paid more and more attention. In this paper, we studied the impact of buried depth of phreatic water under straw returning for soil moisture and evaporation through the combination of simulation and field experiments, the main findings of the study are as follows:(1) If the depth of groundwater is the same, straw returning or not will have a significant impact to soil moisture whose depth of soil is more than0.8m; soil moisture is more higher in straw returning. Straw could inhibit evaporation of diving, and retain water strongly, especially for the0to20cm soil.(2) The experiments of straw returning or not indicate that:straw returning inhibit evaporation rate was between27.3%and39.9%; under the same conditions as in the straw,when the depth of groundwater is0.6to0.8m,the diving evaporation is high. When the groundwater depth is0.6m,the diving evaporation is about8times to groundwater depth of1.6m. the average daily diving evaporation (E) and ground water depth (H) fit for the exponential formula:E=23.448e-2.206H (R2=0.9821), the correlation was significant.(3) in the shallow depth diving area, straw life is not the same, the three methods W0, W4, W10for wheat evaporation and the result is in the order W0> W4> W10; for10consecutive years, the highest inhibition rate reached30.2%; four consecutive years of straw evaporation highest inhibition rate reached22.3%. obviously, the straw could inhibit the evaporation of soil moisture effectively, increased irrigation and soil moisture content, improve crop water status, and with the increase of years of straw, soil evaporation is reduced, the better is the result.For The same straw lives, W4and C4soil evaporation is much larger than the B4Evaporation. (4)in the shallower depth diving regions, with the growth of winter wheat process moves forward, the three processing W0, W4and W10is downward trend among the0-20cm soil layer storage capacity of the overall; W0, W4, W10three processing at0-20cm soil layer soil moisture in descending order of W10> W4> W0.This paper, test results can rediscover the impact of Shallow Groundwater Depth on soil moisture and evaporation under the new farming methods straw returning, providing a scientific basis for human control groundwater depth to change, to improve the shallow groundwater utilization, ease the shortage of freshwater resources, ensure regional food security has an important significance.