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Abstract
This paper proposes an alternative measure of irrigation water efficiency based on the concept
of input-specific technical efficiency. It uses a stochastic production frontier approach, based
on Battese and Coelli’s (1995) inefficiency effect model, to obtain farm-specific estimates of
technical and irrigation water efficiency, and a second-stage regression approach to identify
the factors that influence irrigation water efficiency differentials. This methodology was
applied to a sample of 144 citrus farms in Nabeul, Tunisia. Technical efficiency varies widely,
suggesting that these citrus farmers could increase their production by as much 33% by using
inputs more efficiently. Mean irrigation water efficiency is similarly variable, and on average
below technical efficiency, suggesting that they could produce the same quantity of citrus
using the same quantity of inputs but 47% less water. Finally, the results showed that the
farmer’s age, education level and agricultural training, and the farm’s size, share of
productive trees and availability of water tend to affect the degree of both technical and
irrigation water efficiency positively.