Saline water irrigation in Hetao irrigation district

The fresh water resource is scarce in the Hetao Irrigation District. Therefore, it is of importance to study saline water irrigation and its impact on crop yield and soil salinity balance. A saline water irrigation experiment was conducted in Hongwei Water Saving Irrigation Experiment Station during the growing period of spring wheat, from middle of Apr. to the end of Nov. in 2002. Soil moisture, soil salinity, crop data (crop height and crop yield) and meteorological data (air temperature, air humidity, sunshine hours, air pressure, wind velocity, evaporation, precipitation) were collected. Analyses of the experiment showed that soil salinity was, accumulated after the irrigation when the saline water was used, but the salt can bewashed by Autumn Irrigation. After calibrating using the experimental data, the agro-hydrological model SWAP was used to simulate water flow, salt transport, and crop yield for various scenarios. The scenarios were the combinations of different irrigation levels (3750, 2812.5, and 1875m(3) (.) hm(-2) of irrigation water), different irrigation times (4, 3, and 2 times), and different irrigation water sources (saline water and fresh water). For some scenarios, the salinity content did not increase significantly during the period between the irrigation and seed sowing. Considering soil salinity balance and crop yield, we proposed an optimal irrigation scheme, which included 3 irrigation times, 2812. 5m(3) (.) hm(-2) of irrigation water, and fresh and saline waters irrigated alternatively.