Investigating leaching methods in pistachio micro irrigation system with sustainable use of saline water resources approach (case study: Qazvin Plain)

With the development of localized irrigation in arid and semi-arid areas, the soil is more susceptible to salinization. The salt accumulation in the soil can reduce crop yields, destruction of plants and even resulting the soil uncultivable. In this research, flood leaching and trickle leaching methods (tape) were investigated in a pistachio orchard. Comparing with the flood method, the results showed that, the amount of leaching water used in the trickle method was reduced by 62.7% for the first leaching leading to a total reduction of 26.7%. In the flood leaching method, the entire surface of the farm is leached, while in the 6-row method water to be directly use in saline accumulation areas, which saves leaching water. Also, in the trickle and flood methods the uniformity coefficient of salinity distribution increased by 7% and 3% respectively. In the trickle method, the salt mass balance added due to irrigation can be removed with only one washing step, while in the flood method, the mass of leached salt is less than the mass of added salt. For orchards leaching with localized irrigation, it is recommended to apply more leaching water to salts accumulation areas and for improving the salts management effectiveness low-leaching rates applied alternately is recommended.