MAXIMIZING WATER AND N FERTILIZER USE EFFICIENCIES UNDER WHEAT CROP AT NORTH DELTA

Field experiment was conducted during 2007 cultivation season at Sakha Agricultural Research Station farm, Kafr El-Sheikh Governorate. Split plot design was used; main plots were arranged for irrigation treatments (6 treatments), namely: surface irrigation (I₁) floppy sprinkler (I₂) , semipertable (I₃) , minisprinkler (I₄) ,surface drip (I₅) and subsurface drip (I₆). Sub plots were subjected for nitrogen fertilization treatments (5 levels), namely: 100% soil application (N1), 100% fertigation (N2), 75 % fertigation +25 % soil application (N3), 50% fertigation + 50% soil application (N4) and 25% fertigation + 75% soil application (N5). Results could be summarized as follows:
The lowest value of water applied to wheat (36.59 cm) was achieved under sub surface drip system. On the other side, the highest value of water applied to wheat (57.68 cm) is recorded with surface irrigation system. The highest amount of water stored under wheat crop was 43.68 cm for surface irrigation system and the lowest amount was (33.21 cm) for subsurface drip system. The actual water consumptive use increased with surface irrigation system to the maximum value (43.61 cm). while the minimum value was recorded with subsurface drip system (32.86 cm). The extraction of the soil moisture by wheat roots from the top layer with surface drip irrigation was higher than that with subsurface drip system, the highest irrigation application efficiency (90.75%) was achieved by subsurface drip system compared to the lowest value (74.79%) which obtained with the control (surface irrigation). The highest values of FWUE to wheat (2.05 kgm^-3) was recorded with minisprinkler and the lowest (1.39 kgm^-3) was achieved under floppy sprinkler system. The highest value of CWUE to wheat (2.30 kgm^-3) was resulted from minisprinkler system and the lowest (0.95 kg/m³) was achieved under surface drip system. Subsurface drip system recorded the highest value of (WDE 90%). Also, The lowest value of WDE% (68 %) was recorded with flood irrigation system. Surface irrigation method gave the highest grain and straw yield (3894 and 4117 kg fed ^-1). The lowest yield was obtained by surface drip. Increasing nitrogen addition N2(100% fertigation) produced the highest wheat grain and straw yield (3158.36 and 3445.44 kg fed ^-1). There were high significant differences among irrigation systems on leaf area, spike length and number of kernels/spike.
The highest value of nitrogen use efficiency to wheat grain (45.55) was recorded under I₁ system and the lowest (25.67) was achieved under I₆ system. The highest value of N-recovery to grain wheat (68.76%) was recorded with I₃(minisprinkler) and the lowest (32.89%) was achieved under I₆. Increasing nitrogen units led to an increase in nitrogen use efficiency attributed to N₂ (100% fertigation) was higher than the same obtained in N₁ (100% soil application).The highest values of nitrogen use efficiency were obtained by I₃ N₂ (46.84%), and the lowest one was detected under I₆ N₁ (22.44%), N- recovery increased with increasing N level.  The highest value of N recovery % was found under I₁ N₂ and the lowest one was found under I₆ N₁.