Effect of Fixed Furrow Irrigation on Water Productivity of Cotton Irrigated with Saline Water

Partial Root Zone Irrigation (PRI) has been demonstrated as a promising irrigation method for crops in arid and semi-arid areas. This study verified that fixed furrow irrigation technique could affect the cotton yield irrigated with saline water. A field experiment was conducted for two successive years in summer seasons of 2017 and 2018. Water was applied to furrows either evenly to all the furrows (CFI, conventional furrow irrigation), or to one fixed furrow in every one (FFI1/1F, fixed one furrow irrigation) or to one fixed furrow in every two (FFI1/2F, fixed two furrows irrigation). The results illustrated that, the final seed cotton yield, which was accumulated from two hand-pickings (a traditional local harvesting practice) for the two seasons, produced on average, 76.11 % for FFI 1/1F and 66.19 % for FFI 1/2F of CFI yield. FFI (1/1F) and FFI (1/2F) can save irrigation water by 38.16 % and 45.23 % than CFI. FFI (1/1F) and FFI (1/2F) decreased water consumptive use by about 7.88 % and 20.3 %, respectively, as compared to CFI. It is obvious that, as increasing irrigation water applied the irrigation water productivity decreasing and vise versa with water productivity. The soil moisture content at the beginning of the season was the same in Alternate furrow irrigation treatments FFI (1/1F)& FFI (1/2F) as in conventional furrow irrigation, and when the season went on, they had lower moisture content than CFI. Soil salinity levels decreased with increasing depths of soil, and the change in salinity at deeper soil layers were not as great as in the top 30 cm soil. Furthermore, with growth of cotton plant, soil salinity increased. It can be recommended that under limited supplies of irrigation water and irrigation with low water quality, farmers could use FFI (1/1F) in irrigating cotton but with better fertilizers application in order to improve yield. Generally it can be concluded that, any increase in soil salinity, resulting from these practices, was at levels which could be leached in next winter season with rains.