Agri Kultuur January / Januarie 2016 | Page 15

Figure 2: The use of water resources in South Africa Irrigation is an age-old art and in the words of ND Gulhati of India: “Irrigation in many countries is an old art – as old as civilization – but for the whole world it is a modern science – the science of survival”. Irrigation is of first importance in the more arid regions, but it is becoming increasingly important in humid regions and although irrigation is one of the oldest known agricultural techniques, improvements are still being made in irrigation methods and practices. Everyone involved in irrigation has a certain responsibility:  the researcher, developer, and supplier for providing practical and useful technology;  the designer, who must adapt the design so that it is technical- ly and agriculturally appropriate; and  the producer, who must use the system properly and exercise sound irrigation practices.  the government, who must create an enabling environment for sustainable development of irrigation      A very interesting concept, Virtual Water is the amount of water that is embedded in food or other products needed for its production. Virtual water refers to the amount of water required to produce a good from start to finish or it is the volume of freshwater used to produce the product, measured at the place where the product was actually produced. The following is interesting to know:  It requires 13 litres of water to produce one tomato, It requires 25 litres of water to produce one potato, It requires 50 litres of water to produce one orange, It requires 70 litres of water to produce one apple, It requires 140 litres of water to produce one cup of coffee and It requires 2500 litres of water to produce one hamburger In order to conserve water resources, close attention must be paid to the performance of irrigation systems and continued evaluation and maintenance of irrigation systems are imperative to keep the performance on a high level and to optimize water use efficiency. See figure 3.