Comparison among Different Irrigation Systems for Deficit-Irrigated Corn in the Nile Valley

Abstract

Waterlogging, salinization, and low application efficiency are the main problems inherent with surface irrigation in the Nile Valley. Replacing the surface irrigation method with precise irrigation systems became the main interest of the decision makers and policy planners in Egypt. A field experiment was conducted at Bahteem Experiment Station near Cairo to compare between surface and subsurface drip irrigation and furrow irrigation using gated pipes for irrigating corn. Three levels of irrigation 100, 80, and 60% of potential evapotranspiration (ETp) were compared. The results revealed that the highest amount of water applied for corn was with furrow irrigation using gated pipes (474.4 mm at 100% of ETp), and the lowest amount was with a subsurface drip irrigation system (352 mm at 60% of ETp). The distribution of salts in the soil profile using a subsurface drip irrigation system was not satisfactory compared with surface drip irrigation. Hence, the accumulation of salts around the root zone is considered a disadvantage of using subsurface drip irrigation. Furrow irrigation using gated pipes achieved the best distribution of salts compared with both surface and subsurface drip irrigation systems. Deficit irrigation had significant effect on the plant height, leaf area, plant circumference and the number of ears per plant. Nevertheless, its effect on the number of steps per plant and the number of leaves per plant is not highly significant. The highest value of water use efficiency (2.44 kg/m³) was obtained with furrow irrigation at 100% of ETp followed by the surface drip irrigation system (1.77 kg/m³) at 80% of ETp. The lowest value of water use efficiency (0.97 kg/m³) was recorded with the subsurface drip irrigation system at 60% of water application rate. The highest value of gross margin including fixed cost (925.84 US$/ha/season) was obtained with furrow irrigation using gated pipes, which was 166.3% and 156.3% higher than subsurface drip and surface drip irrigation systems, respectively. Using a higher efficiency subsurface drip irrigation system is recommended for irrigating corn under deficit irrigation in case of water scarcity from a water-saving viewpoint. On the other hand, surface drip is strongly recommended in the areas that have waterlogging problems, but furrow irrigation using gated pipes is very suitable in the areas that have salinization problems to obtain highest yields of corn and highest growth margin in the old lands.