Nufarmer Africa Magazine Sept/Oct 2014 | Page 11

Nufarmer Africa Choosing an Irrigation system Selecting an irrigation system for a site is not always straight forward but depends upon many factors. Often sites are suited to several methods of irrigation and the final selection is based on factors such as water supply, soil, topography, climate, crop, labour availability, energy, initial costs, operating costs, adaptability to farming operations, adaptability for other uses, personal preference, and reliability of the supplier and aftersales service. W hether you are using irrigation for the first time or considering changing from your current irrigation system there are a number of factors one should consider when choosing an irrigation system and the various factors that play a part in the selection include: Water The amount of available water, the quality of the water and the cost thereof may influence the choice of an irrigation system. If the amount of available water is a limiting factor on the area to be irrigated, it might be more profitable to select a micro irrigation system, with high water use efficiency. Where irrigation contains harmful chemical substances that could burn the leaves of the plant or influence the quality of the product, overhead irrigation systems that wet the foliage should be avoided. Soil For micro irrigation of soils with a very high sand fraction, micro sprayers would be preferable to drippers. However, if the soil has a very high clay fraction and a low infiltration rate, a dragline system might be more suitable than a centre pivot is and an overhead system is to be installed. Topography Topography plays an important role where systems such as linear and flood irrigation systems are concerne