REAL-TIME IRRIGATION MANAGEMENT USING THE EPIC-PHASE MODEL AND WEATHER FORECASTS

The real time EPIC-PHASE model developed at Toulouse Auzeville INRA wa s tested on a maize crop. The main objective of the trial was to evalu ate the potential of the model in real time tactical irrigation manage ment based on model predictions every 5 days. The trial compared the r esults of management using simple decision-making rules (SDR) with tho se resulting from model management (MOD). Compared with the standard v ersion of EPIC, which is capable of simulating the evolution of soil w ater content, the option of real time enables integration of intermedi ate states and realization of step-by-step simulations. The trial repo rted here has demonstrated that it is possible to simulate different i rrigation tactics and, hence, different irrigation amounts with weathe r forecasts.Results from the study showed that discrepancies between a ctual and weather forecasts led to a difference in tactical irrigation management. Retrospective simulation carried out with observed data d emonstrated the capabilities of the model under non-limited water supp ly, to be used as an irrigation management tool to save water and reac h a similar level of yield. Use of the model also reduced the risk of overirrigation and associated nitrogen leaching. (C) 1997 Elsevier Sci ence B.V.