A mixed linear programme for short-term irrigation scheduling

For farmers in the UK who use hosereel-raingun irrigation systems, irrigation scheduling requires that three questions be answered: (i) when should each field be irrigated; (ii) how much water should be applied; and (iii) which field should be irrigated first on a particular day? A mixed linear programme has been built to produce optimum irrigation schedules. The objective function maximizes the financial return from irrigation over the short term (typically 7 days). The constraints are equipment, labour and water availability. Use of the mixed linear programme is illustrated with a typical situation faced by a UK farmer.