The distribution rules of soil water in alfalfa field with subsurface drip irrigation

The experiment was conducted in the alfalfa field to study the soil water content distribution after the subsurface drip irrigation, in order to provide some theoretical references for the application of subsurface drip irrigation in alfalfa cultivation. Eleven pressure treatments and three irrigation amounts (600, 750 and 900 m3ha-1 ) were set to evaluate the effect of the different work pressures on the dripper discharge and the effects of the irrigation amounts on the soil water infiltration and redistribution from the horizontal and vertical level. The results showed that dripper discharge increased with work pressure increasing which had logarithmic function relationship. The shape of soil wetting front changed with the time of irrigation which was approximate sphere within 30 minutes of irrigation, and was ellipsoid after 30 minutes, and then was Tanshape after 120 minutes of irrigation. The vertical wetted depth increased with the irrigation amount which had a logarithmic relationship. There were significant differences among soil water content of seven layers (P0.05) after 48 h of irrigation. The 0-30 cm layer had the higher soil water content than the other layers in vertical direction. The soil water content decreased with the distance increase from drip irrigation belt in horizontal direction. The soil water content increased with increase of the irrigation amount at 0-50 cm layer of 10 cm sampling point, other sites had no obvious relationships between soil water content and irrigation amount.