Irrigation strategies in tomato using long term weather analysis

Processing tomatoes (Lycopersicon esculentum Mill.) represent one of the most intensive forms of land use in terms of water requirement. In Mediterranean environments, where water resources are limited, is important to optimize irrigation use efficiencies via use of improved irrigation management practices. The CROPGRO simulation model was combined with 53 years of local historical weather data and it was used as a research tool to evaluate the benefits, risks and costs of seven different irrigation management scenarios and a potential one. Irrigation water was applied i) on reported dates with 3 and 5 days intervals and application rates of 15 and 25 mm and ii) with automatic irrigation started at residual soil moisture levels in the upper 50 cm of the soil profile of 25, 50, or 75%. Based on simulation results it is concluded that irrigation scenario with low amount but with frequent applications ("3-day 15 mm" scenario) resulted in the highest fruit yield; the "5-day 15 mm", on the contrary was the less productive, but with the highest value of irrigation water use efficiency. The irrigation water use efficiency was higher using the soil moisture threshold criteria than the fixed dates and amounts; starting irrigation at CAW 50% the model simulated the highest fruit yield and net return. The optimal average seasonal irrigation amount should be approximately 300-400 mm. The model was confirmed to be a useful decision support system to help the farmers to verify the optimal crop management strategy from several points of view.