EPIC-PHASE: a model to explore irrigation strategies

The erosion productivity impact calculator phase (EPIC-PHASE) model has bee n used to simulate, using 1972 to 1994 climatic date, two irrigation strate gies with a non-limited water supply: (1) a standard strategy based on simp le decision rules advisable for moderately deep soils of the Lauragais regi on (France) and in the Alentejo region (Portugal); and (2) a model strategy based on the daily development of soil water depletion and daily water str ess intensity predicted by the model. At Lauragais, the results show that f or the same level of yield it would have been possible with the model to sa ve 73 mm on average, equivalent of two irrigations per year, compared to th e standard strategy. These savings are due to an increased soil water contr ibution during the cycle and to an earlier end of the irrigation supply. At Alentejo, the results show that for the same level of yield as obtained wi th the standard strategy, it would have been possible with EPIC-PHASE model to save 100 mm of water on average, equivalent of two irrigations per year due to an increased use of soil water during the cycle. Although the resul ts are from simulations it is proved that the standard strategy is inadequa te. Regarding the environmental impact, the model management allows for an increase in the level of water depletion at harvest, delaying the risk of p ercolation and nitrogen losses during the refill period. The EPIC-PHASE mod el proved to be a tool capable of defining an irrigation schedule better ad apted to the Mediterranean region. (C) 2000 Silsoe Research Institute.