A quasi-optimum irrigation season calendar based on economic profit maximization for sloping and runoff-free furrows can be obtained by OPTIMEC (EConomic OPTIMization, in Spanish), a seasonal furrow irrigation model based on the concept of comprehensive irrigation. The model features four components: a soil moisture model, an irrigation hydraulic model, a crop yield model and an economic optimization module. This module uses a Genetic Algorithm (GA), a heuristic technique based on the laws of natural selection, to maximize farmer profit. The GA is a suitable technique to solve the problem of profit maximization due to the difficulties inherent in traditional optimization procedures, which require an explicit function relating flow rate, water depth and profit. For its practical application the model has been implemented in a Visual Basic program. A real case is analysed to compare the irrigation season scheduling using traditional criteria (event by event scheduling) and optimization-based criteria.