Integrated Agro-Economic Approach to Deficit Irrigation on Lettuce Crops in Sicily (Italy)

• Published in: Journal of irrigation and drainage engineering 2008-08, Vol.134 (4), p.437-445
• Main Authors: Capra, Antonina, Consoli, Simona, Russo, Alfonso, Scicolone, Baldassare
• Format: Article
• Language: English
• Subjects: Agricultural and forest climatology and meteorology. Irrigation. Drainage; Agricultural and forest meteorology; Agronomy. Soil science and plant productions; Biological and medical sciences; cost analysis; crop yield; deficit irrigation; evaporation; evapotranspiration; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Irrigation. Drainage; Lactuca sativa; lettuce; microirrigation; optimization; TECHNICAL PAPERS; Water balance and requirements. Evapotranspiration; water use efficiency
• ISSN: 0733-9437; 1943-4774
• DOI: 10.1061/(ASCE)0733-9437(2008)134:4(437)

The effect of four different irrigation levels on the marketable yield and economic return of summer-growth lettuce was evaluated during 2005 and 2006 in Eastern Sicily, Italy. The viability of deficit irrigation was evaluated by estimating optimum applied water levels. Actual evapotranspiration ( ETa ) was estimated by combining pan evaporation measures and the Penman–Monteith approach ( ET0-PM ) . The highest marketable yield of lettuce was recorded for plots receiving 100% ET0-PM . For deficit irrigated plots, reductions in crop production were ascribed to a decrease in lettuce weight. Crop coefficients equal to 1 determined maximum crop production values. Crop water use efficiency was maximum at a 100% ET0-PM level of water applied, corresponding to yield of 0.3 t ha−1 mm−1 . Irrigation water use efficiency reached its maximum at a 40% ET0-PM level, with values of 0.54 and 0.44 t ha−1 mm−1 during 2005 and 2006, respectively. Water applied and marketable yield of lettuce showed a significant quadratic relationship. Cost functions had a quadratic form during 2005 and a linear form during 2006. In the land-limiting condition the optimal economic levels fit the agronomic ones well. In the water-limiting condition, ranges of water deficit of 15–44% and 74–94% were as profitable as full irrigation, thus contributing to appreciable water savings.