Combination of typical meteorological year with regulated deficit irrigation to improve the profitability of garlic growing in central spain

Abstract

This paper shows an adaptation of the typical meteorological year (TMY) method for irrigation schedule forecasting in combination with the optimized regulated deficit irrigation (ORDI) strategy to increase the water productivity of crops and their profitability. This methodology has been simulated using the MOPECO model on garlic (Mulvico cultivar) under deficit irrigation conditions in Castilla-La Mancha (Spain), although it may be useful for other crops and areas in the world. Experimental data from a three-year field test were collected for the calibration (2001) and validation (2000 and 2002) processes. Key objectives of this research were: (1) to adapt the TMY methodology for irrigation schedule forecasting; (2) to calibrate and validate the parameters required for simulating garlic using the MOPECO model; and (3) to determine the most suitable irrigation strategy for the Protected Geographical Indication “Ajo morado de Las Pedroñeras” considering four deficit targets (100, 90, 80, and 70% of maximum evapotranspiration) using ORDI and TMY methodologies. The growing-degree-days for the whole growth cycle are approximately 2044°C, while the calibrated crop yield response (Ky) values for the growth stages proposed by FAO-56 are 0.45 (vegetative period), 0.75 (yield formation), and 0.3 (ripening). The combination of TMY with ORDI may increase yield by 3–9% and gross margin by up to 59% compared to a constant deficit irrigation strategy. When water deficit conditions are present, it is of interest to guarantee nascence but also favour the bulb formation stages as much as possible, inducing water stress during the vegetative development stage. Under the current harvest sale price scenario (1.15€kg−1), this crop reaches a gross margin of around 3400€ha−1 for maximum yield (11,200kgha). Thus, irrigation advisory services can supply important information to farmers that may be translated to higher profitability and crop yield at the farm and/or basin scale.