YIELD AND IRRIGATION WATER PRODUCTIVITY OF RICE ON RAISED BEDS, IRRIGATION INTERVALS AND AMMONIA GAS INJECTION AT NORTH NILE DELTA

Field experiments were conducted in 2014 and 2015 at Sakha Agriculture Research station, Kafr El-Sheikh (31° 07' N Latitude, 30° 57' E Longitude) at North Nile Delta, Egypt to study the effects of raised beds, irrigation intervals and ammonia gas injection levels on productivity of irrigation water (PIW) of rice. A split split plot design with four replications was used. Ammonia gas injection levels were devoted to the main plot, irrigation treatments were allocated in sub-plots and rice planting methods were arranged in sub sub-plots. Ammonia gas injection levels were 70 unit nitrogen N (F₁), 80 units (F₂) and 90 units (F₃). Planting methods treatments were transplanting in flat, as a traditional method (M₁), and transplanting in raised beds only (M₂). Irrigation intervals were irrigation every four days after transplanting (I₁), irrigation every six days after transplanting (I₂), and irrigation every eight days after transplanting (I₃).  Results showed that there was no significant difference on GY between I₁ and I₂ while there were a significant difference on SY, BiomY and other yield components between I₁, I₂ and I₃. The highest values of SY, BiomY and other yield components were obtained from I₂ compared to I₁ and I₃. As for planting treatments, GY, SY and BiomY increased by 20.8%, 40.4% and 31.7% respectively under M₂ compared with M₁. There were no significant differences on GY and its attributes between F₂ and F₃ except SY and BiomY. 
Mean values of water applied for M₁ received the highest amount of IWA to be 14338 m³ ha^-1 compared to M₂ which was 10443 m³ ha^-1, respectively. The amount of water used in M₂ is a feasible amount to grow rice with a 27.2% saving of water. Higher value of PIW of I₂ proved its superiority over I₁ and I₃ treatments by 16% and 7%, respectively. Planting methods treatment M₂ increased NUE by 21% compared to M₁. The highest values of NUE were recorded for I₁ and I₂ without any significant differences between them whereas the lowest one was obtained from I₃. Also, the highest mean value of NUE was obtained under F₁whereas the lowest was under F₃.
Therefore, M₂ could be applied by the farmers’ under irrigation interval of I₂ and 80 units  N as ammonia gas injection (F₂)  because it saved irrigation water by 36% and increased NUE by 17% compared to M₁  x I₁ x  F₁ which in normally practiced in North Delta, Egypt, without any reductions in GY.