Field experiment was carried out at Demo farm of Faculty of
Agriculture, Fayoum University, Egypt during 2012/2013 and 2013/2014
seasons to study the effect of ammonia gas rates, i.e., F1: 80 and F2: 100 kg
N fed-1 (1 kg ammonia gas contain 82.4 % N) and irrigation regime i.e., I1:
irrigation at 40%, I2: 60% and I3: 80% from available soil moisture
depletion (ASMD), at sandy and calcareous soils, on yield, yield
components and some water relations of wheat crop (Giza 168). A split plot
design with four replications was used in both seasons. The obtained results
showed that using 100 kg N fed-1 at 40% ASMD gave the highest averages
of plant height, spike number m-2, 1000-garin weight, spike weight m-2,
straw yield fed-1 (2011.4 and 2334.1 kg fed-1) in sandy soils (Site 1), and
(2539.5 and 2716.7 kg N fed-1) in calcareous soils (Site 2), and grain yield
fed-1 (1888.4 and 2077.4 kg fed-1) in Site 1 and (2209.4 and 2468 kg fed-1)
in Site 2, in the two successive seasons, respectively. The lowest averages of
yield and its components were obtained from applying 80 kg N fed-1and
irrigation at 80 % ASMD, at the two sites in both seasons. Seasonal
consumptive use (ETC) averages were 44.47 and 43.95 cm in 1st season and
45.53 and 45.17 cm in 2nd season, in both sites, respectively. The highest
ETC values were recorded with the interaction (F2I1), whereas, the lowest
values resulted from the interaction (F1I3) in all sites and seasons. Daily ETC
rates were low during November and December, then increased during
January and February, to reach its maximum values during March and then
declined again at April till harvesting. The values of daily ETC decreased
due to decreasing ammonia gas rate in the two growing season's months.
The crop coefficient (KC) values (averages of the two seasons) were 0.47,
0.54, 0.66, 0.70, 0.87, 0.67 and 0.47 in the Site 1 and 0.47, 0.55, 0.63, 0.67,
0.86, 0.67 and 0.49 in the Site 2, for, Nov., Dec., Jan., Feb., Mar., Apr. and
May, respectively. The highest water use efficiency, i.e., 0.96 and 1.04 kg
grains m-3 water consumed at the Site 1, and 1.14 and 1.24 kg grains m-3
water consumed at the Site 2, were obtained from (F2I1) treatments in first
and second seasons, respectively.