Effect of Irrigation Method with Saline Water on Yield of Sorghum and Improving Water and Nutrient Use Efficiency

Population growth as well as global fresh water shortage problem have necessitated the use of unconventional water resources in agricultural sector, as the largest consumer of fresh water, especially in arid and semi-arid regions. In this study, the effect of four irrigation methods on yield, uptake of water and important nutrients, and the salt accumulation in soil was investigated using a completly randomized block design. Treatments included irrigation via fixed furrow with fresh water (FF), irrigation with saline water (SS), irrigation via fixed furrow with saline and fresh water (FFS) and irrigation via alternate furrow with saline and fresh water (AFS). Total crop evapotranspiration during the growing season under FF treatment was 901.2 mm, while for AFS, FFS and SS treatments the values were significantly lower by, respectively, 6.3%, 9.9% and 12.3 percent compared to the control treatment. Despite a significant reduction in the total biomass under FFS (6.34 Mg ha^-1) and SS (5.17 Mg ha^-1) treatments compared with that for FF treatment (7.89 Mg ha^-1), a favorable total biomass under AFS (7.7 Mg ha^-1) caused, 13.2% and 33.8 percent increase in water use efficiency under AFS treatments compared with those for FFS and SS treatments, respectively. Although applying SS and FFS treatments caused a significant reduction in crop nutrient uptake, no significant reduction was observed in total crop nutrient content between AFS (150.3 N, 129.6 K and 21.4 P, in terms of kg ha^-1) and FF (160.9 N, 134.8 K and 21.4 P, kg ha^-1) treatments. Salt accumulation in soil under AFS treatment was also lower than those for FFS and SS treatments. Thus, it could be concluded that applying this irrigation method will lead to 6.3 percent reduction in crop water use, supplying 50 percent of crop water demand by saline water resources, and reduction in crop nutrient demand.  This would protect the economic and environmental issues in the irrigated agriculture in the study area.