Evaluación de los impactos económicos del riego deficitario en el perímetro de riego de Vigia

Abstract

In droughts years, farmers may have to adopt deficit irrigation to cope with limited water availability, which makes this technique to have an increased importance for Portuguese agriculture. Deficit irrigation consists in deliberately apply irrigation depths smaller than those required to satisfy the crop water requirements, thus affecting evapotranspiration and yields. Impacts on yields and related economic results should not be negative and depend upon the adopted irrigation scheduling, production costs, irrigation performances, and yield values. Support to farmers through the use of simulation models may help them to adopt an irrigation management that controls water deficits in such a way that
deficits are applied during the less sensitive crop development stages. The main goal of this work is to evaluate the water productivities of maize, sunflower and wheat crops in some Vigia irrigation district plots, using two soil water balance simulation models – WinISAREG and SIMDualKc. The results analysed through the economic water productivity ratio show that deficit irrigation may be feasible when water costs do not cover the total investment costs and are dependent of the performance of the irrigation systems used by the farmers.