Abstract:
Abstract: Salinization and alkalinization are the prominent land degradation processes in arid areas. In this study, our objective was to demonstrate the three-dimensional distribution of the regional soil salt responding to the change of season in typical zone of Xinjiang Automonous Region. The studied areas are located in typical area of the YiLi district in Xinjiang. The apparent electrical conductivity (ECa) was measured at each site using a Geonics ElectroMagnetic (EM38) instrument in different season. The ECa data collected included measurements using both horizontally and vertically modes. Soil samples were collected at selected sites immediately after the EM38 surveys. A field study was conducted, which was consisted of 70 measurement sites visited in different seasons. In addition, soil samples were also collected between 0 to 0.3 m, 0.3 to 0.6 m and 0.6 to 1.0 m depth increments at the location of the deep cores. Prior to laboratory analysis samples were air-dried and ground to pass a 2-mm sieve. The profile soil salinity was determined from the electrical conductivity of a saturated soil paste extract (ECe) according to standard methods. The profile soil salinity was obtained by regression model using apparent electrical conductivity. The model correlation coefficient differed from 0.875 to 0.952 that indicated high precision accuracy for each model. Three-dimensional soil salt distribution was characterized by inverse distance weighting method for different season. The results showed that average of soil salinity all decreased with increasing depth in the study area in different season. But average of soil salinity moderately decreased with increasing depth in autumn than in spring. The coefficient of variation of soil salinity, an indicative of strength intensity variation for different seasons, ranged from 1.223 to 1.636. Variation of soil salinity decreased with the increase of soil depth in autumn, but variation of soil salinity increased with the increase of soil depth in spring. Map of three-dimensional distribution of the regional soil salt demonstrated that sever soil salinity located in northwest corner of the studied area in autumn and spring. But the area and degree of salinization indicated more serious in spring than in autumn in northwest corner of the studied area. The soil salinity of total profile was more than 6 g/kg soil in northwest corner of study area in spring. Non-saline soil mostly distributed in the studied area in autumn of 2015. Area ratio of non-saline soil for each depth differed 65%, 69% and 81%. Area ratio of non-saline soil increased with increasing depth, area ratio of salinization soil decreased with increasing depth in the study area. Area ratio of different degree salinization soil had slight difference with increasing depth. Area ratio of mild salinization was more than moderate salinization and severe salinization, and area ratio of saline soil (soil salt content more than 6 g/kg soil) was least in 0 to 60 cm depth. Area ratio of moderate salinization was more than mild salinization, and area ratio of severe salinization was least in 60 to 120 cm depth. Non-saline soil mostly distributed and area ratio of non-saline soil increased with increasing depth in study area in spring of 2016. But ratio of saline soil became more than 5% for each depth. The degree of soil salinization and proportion of the severity salinization was significantly increased in the spring of next year than the previous year in autumn. The synthesized method based inverse distance weighting (IDW) method combining electromagnetic induction technique in this study had 0.887 and 0.862 of high correlation coefficient for different season assessment of regional soil salinity. Thus the application of this technique provides a new method to interpretation and evaluation of regional soil salinity response to different season in the three-dimensional spatial distribution characteristics in Xinjiang province.