Study On The Regulation Of Water And Salt Transport For Saline And Sodic Soil Under Drip Irrigation In Datong Basin

As the world population grows, the demand for land resource increase significantly, the contradiction between population and land resources is becoming more and more serious, and saline alkali land is a reclamation of resource, which having great development and utilization value. It is of great significance to solve this contradiction.The key problem to utilize saline alkali land is to handle the relationship between soil water and salt. The emergence of drip irrigation has provided new ideas for development and utilization of saline soil. In this study, by setting the ridge and flat cultivation modes, soil water and salt transfer regulaition of different planting mod-es under drip irrigation condition was investigated in Datong Basin saline land, and the results showed the low salinity areas of ridge cultivation was larger than planting mode. Based on that, three treatments were set then, in which controlled the soil matric potential higher than-5kPa(S1),-15kPa(S2) and-25kPa(S3) respectively, at 0.2m immediately under drip emitter for further exploring soil waterand saltmovement regulation under different matric potential. The study will be beneficial for development and utilization of saline soil in Datong Basin, and the main results were as follows:(1) Ridge Planting within 40 cm in vertical direction from the drip emitters formed low p H region, and flat planting pattern in 0~20cm range formed low p H region. The low p H range of ridge was higher than that of flat.(2) The soil electrical conductivity value within 30 cm in vertical direction from the drip emitters, under two different cultivation modes has decreased by more than 80%. The ridge and flat modes were reduced by 83%, 90% respectively. The ridge made salinity accumulate.(3) The ridge in 0~30cm soil water content were 2% higher than the flat, mainly because the ridge planting increased soil temperature of crop growing period, and the temperature gradient make the water move from furrow to ridge.(4) Irrigation on the p H of 0~10cm soil layer have a certain impact, but with the increase of soil matric potential, the effect of irrigation become smaller, and the phenomenon of high water content and high p H appeared. With the decrease of matric potential, the p H value of the soil layer decreased obviously, that is to say, alkaline salt ions is not easy to be leached in this soil layer.(5) The irrigation amount of each treatment was 307 mm, 247-mm, 183 mm respectively, horizontal diffus ion radius of wetting soil had the following relationship :S1>S2>S3. With the increase of soil matric potential, the horizontal diffus ion radius of wetting soil enlarged, and induced a higher water content in surface soil(0~30cm) in the whole growth period of alfalfa.(6) The different salt ions have the different characteristics of transport and distribution under the ridge drip irrigation. Na+ concentration is more easier leached than K+ by irrigation water, and the leaching of Na+ and K+ is increas ing with the increase of soil matric potential. Na+ and K+ concentration is the lowest near the emitter and have an increasing trend of concentration far away from emiter.(7) From the perspective of the characters and yield of alfalfa, we can conclude that the yield increased with the increase of soil matric potential in this three treatments.