Subsurface Irrigation Under The Conditions Of The Preliminary Study Of The Characteristics Of Different Texture, Soil Water Infiltration

Feature of Soil Water Infiltration under the Condition of Subsurface Irrigation ABSTRACT The test was about soil water infiltration in various kinds of soil by a new micro-hole subsurface irrigation pipe under the conditions of various density and pipe diameter. By measuring accumulation infiltration volume and shift distance of wetting front, the effect of soil density and pipe diameter on soil water infiltration process was analyzed and the relation between accumulation infiltration volume and time, shift distance of wetting front and time was established. The results show: 1 .When soil density is decreased, accumulation infiltration volume increases significant in both of sandy loam soil and medium loam soil. The variation is greater in sandy loam soil. 2.When soil density decreases, shift distance of wetting front in all directions extends obvious in both of sandy loam soil and medium loam soil. The variation is the most significant in the direction of down vertical in both of them.The variation of sandy loam soil is more than that of medium loam soil in the direction of down vertical and horizional. 3.When pipe diameter is extended, accumulation infiltration volume increases significant in both of sandy loam soil and medium loam soil. The variation is greater in sandy loam soil. 4.When pipe diameter is extended, shill distance of wetting front in all directions extends obvious in both of sandy loam soil and medium loam soil .The most variation is in the direction of down vertical in both of them.The variaton is greater in sandy loam soil. 5 When power function is used to show the relation between accumulation infiltration volume and time, the good interrelation can be obtained. 6.The relation between shift distance of wetting front and time square can be achieved by multionxnial polynomial. The interrelation is good. Moreover, the method of finite element is employed to find the solution of unsaturated soil water movement equation. The comparision with the theoretical results coming from Philip method shows the method of the numerical calculation is trustworthy. Thus the basis is founded of simulating soil water movement under the condition of the subsurface irrigation.