In this paper, the soil conductance and salt content in soil under film drip irrigation for 2 and 5 years respectively are measured, and the change and distribution of salt in the improved aeolian sandy soil under drip irrigation for the different years are researched. The experimental field is located at Paotai Town Soil Improvement Experimental Base in the Shihezi region, Xinjiang, the region is close to the marginal zone of the Gurbantonggut Desert, the annual precipitation here is 150 mm and occurs mainly during the period from June to August, but the annual evaporation is as high as 1 900 mm. The salt content in topsoil of 0～30 cm in depth was 9.01 g/kg before improving soil. Four rows of cotton were planted under each piece of plastic film (1.5 m in width), and the wide row spacing and narrow row spacing were 40 cm and 20 cm respectively. The conditions of irrigation and fertilization were the same with the contrast, 10～11 times of irrigation were done, and the water volume of each time of irrigation was 375 m 3/hm 2. The soil samples were sampled from 4 sampling sites at each of the 2 hm 2 sampling fields after implementing film drip irrigation for 2 and 5 years respectively on September 20, 2003 after stopping irrigation and fertilization for 20 days.
The sampling depths were 0～10, 10～20,20～40,40～60 and 60～80 cm, and the sampling sites were 0, 20, 40 and 60 cm away from drippers respectively.The results show that both salt content in topsoil of 0～30 cm in depth and the efficiency of desalination are gradually decreased under the joint effects film drip irrigation with winter irrigation and spring irrigation. Horizontally, soil salt content increases with the increase of distance away from drippers, and vertically, the lowest salt content occurs in soil layer of 20～40 cm in depth. The salt content in topsoil of 0～40 cm in depth decreases gradually downward. The extent of desalination is enlarged with the time of drip irrigation. Desalination is not so obvious in deep soil under drip irrigation for the different years. Salt accumulation occurs in topsoil of 0～40 cm in depth where the ground surface is not covered with plastic film.