Water Productivity in a Mediterranean Semi-Arid Greenhouse District

An irrigation performance analysis has been carried out in a horticultural greenhouse area located in the "Campo de Nijar" (Southern Spain) in order to assess its irrigation productivity. Irrigation water productivity indicators were calculated for a wide sample of crops over the course of two different study periods. These productivity indices were similar in average to those reported in other nearby greenhouse irrigation districts although their variability was very high. The overall productivity ratio (CYR) was 73.9 %. The low values for CYR were expected as irrigation water in this area has high salinity levels and low irrigation leaching fractions were applied. The influence of type of crop, greenhouse technology and agricultural season in the CYR values was analyzed. None of these factors had a statistically significant influence. A multivariate regression analysis was performed to model the crop yield as a function of several quantitative variables. The results showed that the most significant variable was the relative irrigation supply (RIS). Other variables that had an influence of the productivity were the length of the growing cycle in the case of tomato and the number of greenhouses per farm in the case of watermelon. Results of this work are useful as they highlight the weaknesses of the system and suggest possible measures in order to improve its productivity and sustainability.