Effect of Soil Matric Potential on Poplar Growth and Distribution of Soil Salt under Drip Irrigation in Saline-sodic Soil in Aarid Regions

Abstract：Field experiments were conducted to investigate the effects of soil matric potential under ridge-mulch drip irrigation on poplar growth and soil salt distribution in saline soil land.The experiment included five treatments,in which controlled the soil matric potential higher than-5 kPa(S1),-10 kPa(S2),-15 kPa(S3),-20 kPa(S4) and-25 kPa(S5),respectively.All treatments were repeated three times with the experimental plots following a complete randomized block design.Results showed that after the first irrigation season,the root zone soil salinity in the whole soil profile decreased by 67% compared with that before transplanting.Different irrigation regimes applied in the second year and soil salinity content were different for each treatment.Due to more amount of irrigation water applied in S1(-5 kPa) and S2(-10 kPa) treatments,more soil salt was leached effectively than that in other treatments and the root zone salt salinity decreased by 79% compared with that before transplanting.Owing to less amount of irrigation water applied in S5 treatment,more soil salt rose with the decreasing of soil depth than those in the other treatments and the soil salinity increased dramatically when the soil depth was below 40 cm.After two years growth,the survival rate of each treatment was kept above 92%.Additionally,the increased amount of poplar DBH rose with the increasing amount of irrigation water.The research results have a theory and application value for the water and soil salt regulation and poplar irrigation scheduling on saline-sodic land.