Two field experiments were established in 2014/2015 and 2015/2016 winter seasons at Sakha Agriculture Research Station (31° 07' N latitude, 30° 05' E longitude), North Nile Delta, Egypt. Objective of the investigation is to improve productivity of water and wheat yield in shallow water table area. Irrigation scheduling treatments were assigned in the main plot, fertilizer levels were allocated in the sub-plots. While microorganisms treatments were allocated in sub sub-plots. Irrigation scheduling was done at 50%±5 (I1), irrigation at 70% ±5 (I2) and irrigation at 90%±5 (I3) of available soil moisture depletion (ASMD). Treatments of nitrogen fertilizer were 75% (F1) and 100% (F2) of the recommended nitrogen fertilizer. The plant growth promoting rhizobacteria treatments (PGPR) were cyanobacteria (Cy), Rhizobium (R) and consortium cyanobacteria and Rhizobium (Cy +R) as well as the control treatment without inoculation (C).
Results revealed that there are no significant differences in grain yield, harvest index, number of spikes m-2 and weight of 1000 grains between I1 and I2. Grain yield under I3 decreased by 11% and 8% compared to I1 and I2 respectively over both growing seasons. The values of wheat consumptive use and irrigation water applied has the descending order I1 > I2 > I3 over both growing seasons. The seasonal water consumptive use was 30.22, 26.25, and 22.81 cm for I1, I2 and I3 respectively. Irrigation water applied was 39.02cm, distributed on five irrigations, 32.43 cm, distributed on four irrigations, and 27.36 cm distributed on three irrigations including seedling irrigation for I1, I2 and I3 respectively. Total seasonal water requirement was 50.0, 47.38 and 45.75 cm for I1, I2 and I3 respectively over both seasons. Mean percentage of groundwater contribution has the descending order I3> I2 > I1 to be 46%, 26.9% and 10.2% for I3, I2 and I1 respectively over both seasons.
So, when water becomes a limiting factor for wheat productivity in such area, farmers can apply I3 with F1 and Cy +R because it increased productivity of irrigation water (PIW) and water productivity (WP) by 37% and 79% respectively, as well as saved nitrogen fertilizer and irrigation water by 25% and 30% respectively compared to I1 with F2 and C.