EFFECT OF IRRIGATION AND NITROGEN ON YIELD, YIELD COMPONENTS AND WATER-USE EFFICIENCY OF BARLEY IN SAUDI-ARABIA

Water use efficiency and yield of barley were determined in a field ex periment using different irrigation waters with and without nitrogen f ertilizer on a sandy to loamy sand soil during 1994-1995 and 1995-1996 . Depending upon different fertilizer treatments, the overall mean cro p yield ranges for two crop seasons were: greenmatter from 19.48-55.0 Mg ha(-1) (well water) and 21.92-66.5 Mg ha(-1) (aquaculture effluent) ; drymatter from 6.86-20.69 Mg ha(-1) (well water) and 7.87-20.90 Mg h a(-1) (aquaculture effluent); biomass from 4.12-21.31 Mg ha(-1) (well water) and 8.10-19.94 Mg ha(-1) (aquaculture effluent) and grain yield from 2.12-5.50 Mg ha(-1) (well water) and 3.25-7.25 Mg ha(-1) (aquacu lture effluent). The WUE for grain yield was 3.37-8.74 kg ha(-1) mm(-1 ) (well water) and 5.17-11.53 kg ha(-1) mm(-1) (aquaculture effluent). The WUE for total biomass ranged between 6.55-33.88 kg(-1) ha(-1) mm( -1) (well water) and 12.88-31.70 kg ha(-1) mm(-1) (aquaculture effluen t). The WUE for drymatter was 10.91-32.90 kg ha(-1) mm(-1) (well water ) and 12.51-33.22 kg ha(-1) mm(-1) (aquaculture effluent), It was foun d that grain yield and WUE obtained in T-4 and T-5 irrigated with well water and receiving 75 and 100% nitrogen requirements were comparable with T-4 and T-5 irrigated with aquaculture effluent and receiving 0 and 25% nitrogen requirements. In conclusion, application of 100 to 15 0 kg N ha(-1) for well water and up to 50 kg N ha(-1) for aquaculture effluent irrigation containing 40 Mg N l(-1) would be sufficient to ob tain optimum grain yield and higher WUE of barley in Saudi Arabia. (C) 1998 Elsevier Science B.V.