The Study On The Character Of Water And Salt Distribution In Soil Under Field Drip Irrigation

Drip irrigation under film has been used in Xinjiang region for utilization of saline-alkali soils and protecting from secondary saline and alkaline. But still there is a long way to go for making appropriate leaching and irrigation norm to guide agricultural production. In this paper, the characters of water and salt transport in soil under infiltration and evaporation are analyzed based on the experiment data of drip irrigation grape under film and the concerning research achievement at home and abroad. Major results as follows.(1) Under the single dripper irrigation the power function may be used to describe the relationships among the pond-water area, horizontal wetting front and the infiltration duration respectively and both smaller dripper charge and longer infiltration time are good for longitudinal leaching. As evaporation is considered, for the treatment with film the water content in soil is more in layer 20-30cm, where the front of salt content occurs while it is in 0-10cm without film.(2) Under drip irrigation grape in field, the water content below dripper is positive correlation with irrigation norm while salt content is negative and decreases remarkably with deep increasing. The irrigation norm has small effect on water content in soil that the edge of two adjacent drippers but large effect on salt content. The salt content in upper soil with 60cm far from dripper treated with film is higher obviously than that without film. But the case is on contrary in 40cm and the difference decreases with deep increasing. During the growing season of grape the maximum average water content in soil with film treatment occur in 30cm horizontally far from dripper and the maximum salt content is in 30-60cm. The longer the irrigationperiod is, the greater the significant becomes. As the case of the same irrigation norm three day period is the best for leaching.(3) After eight-day evaporation the maximum average water content treated with film appears in 60cm horizontally far from dripper. The salt content of soil in 0-30cm horizontal is approximate constant and in 60cm increases obviously for the film treatment.(4) After the growing season the water content is much higher than initial content. Both the amplitude of salt content increases as the distance from emitter and the effectiveness of leaching are negative correlation with irrigation period. For the treatment of film and three-day period without film, there is no salt cumulative in the area of 60cm from emitter horizontally and 1 meter depth.(5) Considering all these factors of water content, salt limiting and crop yield, the optimum scheme fitting local environment is determined. It is the treatment with three-day period, irrigation norm of 209 m³Â·hm^-2 and film.