Effect of soil matric potential on the distribution of soil salt under drip irrigation on saline and alkaline land in arid regions

Field experiment was conducted to investigate the effect of soil matric potential on the distribution of soil salt under ridge-mulch drip irrigation on saline and alkaline land in arid regions. The experiment included three treatments, in which controlled the soil matric potential higher than -5 kPa (S1), -15 kPa (S2) and -25 kPa (S3), respectively, at 20 cm depth immediately under emitter. All treatments were repeated three times with the experimental plots following a complete randomized block design. Results show that the different salt ions have the different characteristics of transport and distribution under mulch drip irrigation. Na⁺ and Cl^- concentration easily leached by irrigation water is the lowest near the emitter and have an increasing trend of concentration far away from emitter. The leaching of Na⁺ and Cl^- is increasing with the increase of soil matric potential. There are linear relations of total dissolved solids to the concentration of Na+ and Cl- in the experiment area, respectively. Mg²⁺, Ca²⁺ and HCO^3- content are less influenced by soil matric potential, which have not obvious correlation with total dissolved solids and have relatively uniform distributions in the soil profile. The leaching of total dissolved solids mainly appears in the periods of the first drip irrigation with large amount of water on the same day after seeding and the later irrigation with high soil matric potential at seedling stage. There are less effects of irrigation water on the leaching of total dissolved solids at the latter stages of crop growth. The research results have a theory and application value for the water and salt regulation in soil and irrigation scheduling on saline and alkaline land.