IRRIGATION WATER USE EFFICIENCIES AS INFLUENCED BY IRRIGATION SYSTEM AND RATE OF APPLIED N FERTILIZER TO MAIZE PLANT

Two field experiments were carried out during the two successive summer seasons of 2006 and 2007 at Bahteem, Water Requirements Research Station., El Kalyobia Governorate –NationalWaterResearchCenter. Maize (Zea mays, single cross 10) was grown on the investigated soil under two irrigation systems i.e. surface irrigation (G1) and drip irrigation (G2) Nitrogen fertilizer was applied in the form of urea (46% N) at four rates N1 (0kg), N2 (90kg), N3 (120kg), and N4 (150 kg N /fed. Other cultural practices were done as recommended. The experiment was arranged in a split plot design.The irrigation systems were distributed uniformly in the main plots, while, the nitrogen treatments, were distributed randomly in the sub-plots.
 Results showed that application of nitrogen regardless of its applied ratm could save 24.15 and 24.05% m³/ fed within the first and second seasons, respectively under tie surface irrigation system. Under the drip"irrigation system the correspooding saved amount of the water requirement reached 37.93 and 38.03%, within the first and second seasons, respectively. Values of monthly and seasonal actual water consumptive use (Cu) were higher when irrigation water was applied by surface irrigation system than drip irrigation system. Values of (Cu) were decreased by i~creasing rate of the applied N. Thå highest attained values of irrigation water application effiãiency occurred under the drip irrigation system (G₂) end N₂ trmatments in the first and second growinw seasons. There was a decline yn crop water use efficienc} with!surface irrigation sysôem in both seisons/ as compared wéth the drip érriga|ion system® Xowever the miximum value of crop water use efficiency was obtáingd$under the drip irrigqtion system (G₂) and application of nitrogen fertilizer at a rate of 120 kg/fed. The field water use efficiency was highev under the drip irrigation system than under the surface irrigation one. Values of this parameter increased with increasing rate of the applied N up to 120 kg/fed beyond which it decreased obviously.