Irrigation made easy Part 10:
Land preparation for flood irrigation
A
ll flood irrigation systems require intensive and accurate preparation of the land prior to planting. Accurate levelling of the fields is essential. On larger basin and flood irrigation systems, this can only be achieved using a laser-controlled levelling apparatus. This type of land treatment is expensive and generally not available to remotely situated small-scale farmers. The levelling of flood basins and short furrows can be achieved by the farmer with normal farming implements. Training and education are, however, important. An efficient flood irrigation scheme can provide water more efficiently than alternative systems, such as a sprinkler system. A poorly managed flood irrigation scheme wastes considerable quantities of water. If irrigation application is inefficient, reduced yields can be expected. For short furrow irrigation, the level furrows can easily be set out using simple equipment such as a hose and water to align the furrows. The furrow bed can also be levelled by filling it with water and removing humps and bumps by hand as the water slowly seeps into the soil. More extensive land levelling is needed for other types of flood irrigation. For short furrow and similar systems, it is significantly easier to manage irrigation by using fixed applications. (The same depth of irrigation water is applied with each application.) Scheduling is simplified and one of the following models should be used to control irrigation: Both the time lapse between irrigations at a point, and the application 20
Figure 1: An easy method to determine the ground level over a distance.
Figure 2: The bed (bottom) of the furrow can be levelled by filling the furrow with water and using hand tools to move soil from high points to depressions. As the water sinks into the ground all uneven bumps and dips will become exposed.
Once a level base has been established, even applications of water can be applied by placing a brick or similar object in the furrow bed to act as a filling guide.
ProAgri Zambia 59
