The aim of this paper was to evaluate the effects of surface drip irrigation (D.I.) and gated pipe (G.P.) furrow irrigation systems at four levels of irrigation 120%, 100%, 80% and 60% of the crop water requirement (ET_c) on maize (Zea mays L., Varity Single Cross No. 10) grain yield and irrigation water use efficiency in heavy soil. The experimental design was a split- block design (strip design) with four replications in a randomized complete block design. Field study was conducted at Itay El- Baroud, El-Beheira Governorate, Egypt.
CROPWAT model was used to evaluate drip and gated pipe irrigation systems and on crop performance under different water irrigation amount. The results showed that there was no significant amount of water losses by deep percolation (DP) in drip irrigation treatments except, in case of crop stress coefficient (Ks) = 1.2, where the DP losses was 52.4 mm which represent 0.8 of the least value of DP losses in furrow gated pipe irrigation treatment at Ks = 0.6. However, under G.P. furrow irrigation the DP reached 225, 135.1, 84.8 and 65.2 mm at gross irrigation depth (dg) of 670.3, 578.5, 486.8 and 395.1 mm respectively.
The field results revealed that the highest amount of water applied was 6702.5 mm at 120% of ET_c with G.P. furrow irrigation, and the lowest amount was at surface drip irrigation (D.I.) 2774.9 mm at 60% of ET_c. Nevertheless, the highest grain yield was 12.89 t/ha resulted from drip irrigation, and the lowest grain yield was 5.17 t/ha from G.P. furrow irrigation. The highest values of water use efficiency were 3.12, 2.83 and 2.75 kg/m³ which obtained from surface drip irrigation at 80%, 100% and 60% of ET_c respectively.
The lowest values of water use efficiency were 1.31, 1.59 and 1.6 kg/m³ which obtained at 60%, 80% and 120 of ET_c with G.P. furrow irrigation system respectively. However, D.I. showed grain water production (GWP) better than G.P. by 40% more production with lowest amount of water by 7%.
The statistical analysis of variance revealed highly significant interaction of (irrigation system * irrigation treatment) for all traits studied. The drip irrigation (D.I.) * Ks (1.0) considered the best treatment for most traits, but D.I. * Ks (0.8) is considered the best treatment for GWP in Kg/m³. In average, drip irrigation consumed 74.7 % of water compared to the furrow gated pipe irrigation system at the same water stress. Thus, achieving higher water use efficiencies. This study showed that, for water saving and achieving high water use efficiency, the present study recommended using surface drip irrigation for maize crop in heavy soils over gated pipe furrow irrigation.