Analysis of on-farm irrigation performance in Mediterranean greenhouses

Abstract A comprehensive irrigation assessment was conducted using on-farm water use information and simulated crop water requirements in a Mediterranean greenhouse area, mainly dedicated to horticultural crops, located on the Almeria coast. The mean irrigation water supply (IWS) for the main greenhouse crop cycles was 228 mm and ranged from 158 mm (autumn green bean) to 362 mm (autumn–spring sweet pepper). Besides, the mean AIWS value for the main crop rotations was 444 mm and ranged between 363 mm for autumn–spring sweet pepper and 502 mm for autumn–winter pepper and spring melon. Mean relative irrigation supply (RIS) values were close to 1 for most greenhouse vegetable crops, indicating that, on average, the irrigation supply matched the maximum water requirements of these crops. By contrast, the mean RIS value of autumn–winter cucumber was 1.6, indicating that, on average, the irrigation supply clearly exceeded the calculated optima. However, for most crops, the high CV values observed for RIS and the analysis of the RIS dynamics throughout the cycles indicate that there are greenhouse crops and crop cycle periods for which the IWS clearly does not match the crop water requirements. Greenhouse irrigation water use in the Almeria coastal region can, therefore, be improved. Mean irrigation water use efficiency (IWUE) values for greenhouse horticultural crops ranged from 15.3 kg m −3 (autumn–winter green bean) to 35.6 kg m −3 (spring watermelon). They were, in general, higher than those found when these crops were grown outdoors in similar climatic regions. Water productivity (WP) varied from 7.8 to 15.9 € m −3 and were highest for green bean crops. WP values of greenhouse crops were generally much higher than those found in other irrigation districts around the world, including Mediterranean areas, due to the low IWS and, especially, to the high value of the vegetable crops grown off-season.