Improving the Effectiveness of Rain-Fed Agriculture by Increasing Soil-Water Retention

Abstract

The problem of food production gaps is severe in Africa and other regions of the world. In sub-Saharan Africa 90% of the population depends on rain-fed agriculture for food production. Rainfed agriculture is important globally as it covers 80% of the arable crop land providing 60% of global food and fiber production. The current yield levels in rainfed systems in sub-Saharan Africa for wheat crop average at 1t/ha are well below the potential levels off 5t/ha achieved else-where. Egypt is one of the arid countries of Africa, so this thesis focuses on increasing the effectiveness of rainfed agriculture by increasing the available water to plants to increase the actual evapotranspiration to meet potential requirements. In this work, Hydrus-2D was used to simulate water infiltration and redistribution in sloping terraces located in the North Coast of Egypt as an arid region and in the Abha region of Saudi Arabia as a semi-arid region. Hydrus-2D was applied over a full growing season to evaluate different techniques of increasing soil water retention for different soil types, different rainfall patterns, different land slopes, different distance between trenches (5m, 10m and 20m) to capture the surface runoff and different crops. Provision of supplemental irrigation in the trenches was also studied. In each simulation the ratio between actual evapotranspiration to the potential evapotranspiration (of wheat and barley) was taken as a measure of the system effectiveness. Modeling results showed that trenches and trenches with supplemental irrigation has the potential to double or triple crop production.