Irrigation water efficiency in wheat production in Chbika (Tunisia):Parametric versus Nonparametric Comparisons

The aim of this paper is to estimate the water use efficiency of wheat farms in irrigated areas in Chbika (Central Tunisia). Both Stochastic Frontier and Data Envelopment Analysis approaches were used for this purpose. Data were collected from 170 wheat farms during 2010-2011cropping season. The empirical results show that the average water use efficiency measured using the Data Envelopment Analysis (DEA) method was around 41% under constant returns to scale and 43% under variable returns to scale while it was 47% when calculated by the Stochastic Frontier Approach (SFA). This suggests that there is substantial scope for improving irrigation water use efficiency in the study region using the existing technology on wheat farms. Spearman’s rank correlation coefficient between both methods in measuring irrigation water use efficiency, for our sample of wheat farms it is positive and significant at the 1% level. However, the average technical efficiencies obtained from the Stochastic Frontier method are higher than the ones estimated from Data Envelopment Analysis. This comparison shows that further empirical researches on sub-vectors efficiency calculation approaches are needed in order to obtain more accurate results than these estimations.