RESUMO
In high water table level area, saline water irrigation in crucial drought periods has been confirmed to have a positive effect to increase crop yield while it may cause soil salt accumulation to have a potential negative effect on next season crop growth. It was supposed that eliminating or reducing this kind of negative effect could ensure a sustainable increase of crop yield under saline water irrigation. Field experiments were completed in a 2year period in Nandagang district in coastal area of Hebei Province. We investigated the dynamic changes of soil salt accumulation under saline water irrigation in dry season, and analyzed the ecological effect of removing soil salt storage by subsurface pipe drainage system in rainy or proper season. The results showed that the soil salinity experienced accumulation-desalinization-secondary accumulation under saline water irrigation in dry season. In the early stage of irrigation, under 1 g·L -1 concentration saline water irrigation treatment, the soil salt load was obviously removed in the layer of 0-50 cm, the soil salinity went up with soil depth, HCO3- content increased whereas other ions contents decreased; under 6 g·L- and 13 g·L-1 concentration saline water irrigation treatments, the soil salt accumulated in the layer of 0-50 cm, the soil salinity went down with soil depth, HCO3-content decreased whereas other ions contents increased. Leaching effect of soil salt under subsurface pipe drainage system during rainy or proper season was significant. The soil desalinization ratio increased with the rainfall strength, ranging from 16.0% to 45.7%. On a yearly scale, the soil salt accumulation under saline water irrigation was lower than that in control area. The wheat yield under saline water irrigation was significantly higher than that in control area, and the yield in the treatment of 1 g·L-1 was highest.
