Mumba R. Mwape1, Derek M. Heeren2,3, Dean Eisenhauer3, Aaron Mittelstet2,3 and Laszlo Hayde4
1: Zambia Agricultural Research Institute, Zambia, 2: University of Nebraska-Lincoln, USA, 3: Robert Daugherty Water for Food Global Institute, USA, 4: IHE-Delft Institute for Water Education, Netherlands
Zambia has been making various reforms aimed at improving the agriculture sector for the past two decades. Recent developments have seen a streamlined focus on irrigation as a means of increasing production and productivity to bring about sustainability in the agriculture sector, which had previously been dependant on rainfall. These efforts have been directed at small-scale farmers who have been impacted by reduced rainfall due to climate variability. The high cost of irrigation equipment and the urgent need to increase food production entails that irrigation plans guarantee sustainability, effectiveness and efficiency. This research was aimed at evaluating the suitability and viability of community irrigation systems, and designing systems for two sites (of 60 ha each) in Masaiti and Samfya in agro-ecological region III of the country using surface (river) and ground (well) water sources respectively.
Field infiltration test (taking readings)
In establishing the suitability of the areas, soil tests such as infiltration and texture analyses were conducted as well as the depth of the soils. The quality of water was assessed for different parameters for toxicity levels that may restrict water use in irrigated agriculture. To determine the quantity of water, a pumping test was carried out for ground water while 20 year monthly flow rates of the river were used for surface water. Land and water availability were also assessed. Aquacrop was used to determine the crop water requirements and the yield potentials and based on the yield potential results, the most profitable crops with the least water requirements were selected. The soil tests showed high infiltration rates of 10 cm/hr and 11.6 cm/hr for Masaiti and Samfya respectively. This led to the recommendation of only sprinkler and drip irrigation systems. The pumping test gave a potential yield of 110 l/s while the river’s 20-year average flow rate gave 2 m3/s and 26.6 m3/s as the lowest and highest rate respectively. The quality of the water from both sites was found to have no restriction to agricultural use according Food and Agriculture Organization (FAO) standards. The crops selected, for a 60 ha irrigation system, had a water requirement of 50.8 l/s when water is not limited and 34.5 l/s if staggered planting dates are used. This water requirement can be supplied by both sources that were analysed, up to 2 irrigation systems by the well and 9 irrigation systems if 25% of the river’s lowest flow rate is diverted for use. The land tenure system in the area is customary and farm sizes per household was between 5->50 ha and while cultivation was less than 10% of the total area owned. The economic analysis of the irrigation development for a center pivot and drip irrigation system gave a positive outlook with an improvement in yield of 65% to more than 100% and with a profit margin per ha approximately 10 times more than the profit of current production practices.
