RESPONSE OF MAIZE CROP TO IRRIGATION UNDER DIFFERENT RATES AND DOSES OF NITROGEN FERTILIZATION IN THE NORTH NILE DELTA REGION

Two field trials were carried out at the experimental farm, sakha agricultural research station, kafr el-sheikh governorate during the two successive summer growing seasons of 2012 and 2013. the research aimed to study the effect of irrigation at different soil moisture depletion (h: at 45%, i2: at 60% and i3: at 75% depletion of available soil moisture, respectively), nitrogen rates (n1 60, n2: 90 and n3: 120 kg n fed-1) and doses number of nitrogen application (d1 one dose, d2: two equal doses and d3: three equal doses) on maize yield and its components, nitrogen uptake by plants, n-use efficiency and some water relations. the experimental design was split split plot with three replicates, the main plots were for irrigation treatments, where the sub plots were for n-rates and the sub-sub plots were for doses number of n application.the main results can be summarized as follows:•irrigation at 75 % depletion of available soil moisture (i3) decreased seasonal water applied, water consumptive use and water stored in the effective root zone by 18.08, 16.78, and 17.02%, respectively compared with irrigation at 45% depletion. also, the highest means of water productivity (wp) and productivity of irrigation water (piw) were 1.95 and 1.24 kg/m3, respectively with irrigation at 60 % depletion (i2).•irrigation at 60% depletion (i2) recorded the highest mean of water application efficiency (89.60%), whereas the irrigation orders was h> h>h.•irrigation at 45% depletion (i1) recorded the highest mean for grain yield (3.363 ton fed-1), stalks yield (9.313 ton fed-1), weight of 100 grains (43.899g) and ear weight (316.119g).•application of n-rate n3 recorded the highest means of grain yield (3.507 ton fed-1), straw yield (9.56 ton fed-1), weight of 100 grains (43.176g) and ear weight (310.948g), respectively.•application of n-rate at three doses (d3), recorded the highest means of grain yield (3.585 ton fed-1), straw yield (9.216 ton fed-1), weight of 100 grains (43.466g) and ear weight (315.202g).•irrigation at 45% depletion (i1) recorded the highest mean of n-uptake for grains and stalks.•application of nitrogen rates increased n-uptake for maize grains and stalks up to n3.•increased the doses number of n application increased n-uptake for maize grains and stalks up to d3 (three equal doses).•the values of nue increased by 15.65% with splitting n-rate into three doses compared with application at one dose, but decreased with increasing application n-rate and irrigation at 75 % depletion.•most of interactions among irrigation, nitrogen rates and doses number of n application showed significant effect on grain yield and its components and n-uptake in both maize grains and stalks, and positive effect on n-use efficiency