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Abstract
The objective of this paper is to measure productive efficiency of irrigation water
efficiency based on the concept of technical efficiency and compared among different sizes farms. The
proposed methodology is applied to a randomly selected sample of 144 citrus growing farms located
in Nabeul (Tunisia) and differentiated by size (small, medium and large farms). A stochastic
production frontier approach, based on Battese and Coelli’s (1995) inefficiency effect model, is used
to obtain farm-specific estimates of technical and irrigation water efficiency. The last step of the
analysis consists on the identification of the factors influencing irrigation water efficiency differentials
across citrus growing farms on the basis on a second-stage regression approach.
Empirical results show that estimated mean technical efficiency ranges from a minimum of
12.82% to a maximum of 90.69% with an average estimate of 67.73%. This result means that
32.3% increase in production is possible with the present state of technology and unchanged
input uses, if technical inefficiency is completely removed. Thus, improving technical
efficiency will result to significant increases in framer’s revenue and profit.
On the other hand, mean irrigation water efficiency is found to be 53%, which is much lower
than technical efficiency and also exhibits greater variability ranging from 1.6% to 98.87%.
The estimated mean irrigation water efficiency implies that the observed quantity of
marketable citrus could have been maintained by using the observed values of other inputs
while using 47.0% less of irrigation water. This means that farmer’s can achieve significant
savings in water use by improving the utilisation of irrigation system and by utilizing more
advanced irrigation technologies.