Effect of water supply pressure on soil water movement in different soil textures under subsurface irrigation with porous pipe

Numerical simulation of soil water movement is one of effective measures to study the dynamic regular pattern of soil water. With the help of HYDRUS-2D computer program, the numerical simulation of soil water transport was conducted within the pressures of water supply from 100 cmH(2)O to 1000 cmH(2)O in different soil textures of Meadow Brown Soil under subsurface irrigation with porous pipe in the paper. Results show that numerical simulations are convergent under the water supply pressure within 100-1000cmH(2)O in loam soil, 100-600cmH(2)O in loam sand soil and 100-400cmH(2)O in clay soil, respectively. The time for the wetting front of subsurface irrigation water reaching into the soil surface, 60cm below and 70cm lateral to the porous pipe buried 30cm soil depth was decreasing with the increasing of water supply pressure. It was monotonously on the decrease within the pressure of 100-1000cmH(2)O and 100-400cmH(2)O water supply pressures in both loam soil and clay soil, but invariableness as the water supply pressure over 500cmH(2)O in loam sand soil. The effect of subsurface irrigation with porous pipe was better as applied in loam soil than in both loam sand soil and clay soil. The rate of water movement was enhanced as the increasing of water supply pressure within the certain range of water pressure. The results of determined infield are agreed with those in numerical simulation.