Investigation of salinity distribution in the root zone of pistachio trees in surface, bubbler and drip irrigation methods

The objective of this research was to investigate the effects of surface, bubbler and drip irrigation methods on salinity distribution around pistachio trees under gardener management in a soil with sandy clay loam texture. For this purpose, an experiment in the form of split split plots with three treatments of irrigation methods in the main plot, the distance from the row of trees at four levels (0.5, 1, 2 and 3.5 meters) in the sub-plot and the depth of soil at four levels (0 to 30, 30 to 60, 60 to 90 and 90 to 120 cm) in the sub-sub plot in three replications was done. Then applied water and soil salinity during two crop years were measured. According to the results, the amount of applied water in border, drip and bubbler irrigation was 8150, 5060 and 6390 m3c/ha, respectively. The effect of irrigation methods and distances from trees on soil salinity was significant at 1% level and showed that drip irrigation is superior to other methods. Salt distribution at different distances from the trees row also showed a significant difference. Solutes accumulation under drip irrigation has started in surface layer at the edge of the wet environment and at a distance of 70 to 80 cm from the row of trees. Accordingly, the drip irrigation is one of the suitable irrigation methods for pistachio gardens, under properly designed, implemented and operated and soil sustainability consideration, and it is a suitable alternative to the conventional surface irrigation. In drip irrigation, the amount of irrigation water was 38% less than the surface irrigation. It is obvious that in the areas where the irrigation water is not a good quality and the effective annual rainfall unable to leaching the soil, the soil should be leaching annually using the surface irrigation method.