Monday, November 5, 2007 - 9:30 AM
33-1

AquaCrop--The FAO Field-Crop Model to Predict Yield Response to Water.

Pasquale Steduto, Water Resources, Development and Management Service, Land and Water Division, FAO, Room # B-721, Via delle Terme di Caracalla 00100, Rome, Italy, Theodore C. Hsiao, University of California, Department of Land, Air and Water Resources, One Shields Avenue, Veihmeyer Hall, Davis, CA 95616, Elias Fereres, University of Cordoba, ETSIAM, Depto. de Agronomia, Cordoba, 14080, Spain, and Dirk Raes, K.U.Leuven, Faculty of Bioscience Engineering, Division of Soil and Water Management, Celestijnenlaan 200E - PostBox 02411, B-3001, Leuven, Belgium.

During the last few years, a team of climate, crop, soil, irrigation, and water scientists and experts from various countries and research centres, including CGIAR, gathered regularly under the auspices of FAO to discuss the developmental approaches and the implementation tools for re-addressing and revise the “yield response to water” Irrigation and Drainage paper n. 33. For the field-crops, a model named AquaCrop has been developed. The most significant peculiarities of the model are: (i) separation soil evaporation from crop transpiration; (ii) expressing yield via biomass and harvest index; (iii) the biomass water productivity (or biomass water use efficiency) relationship is at the core of the model growth-engine, classified as water-driven; (iv) a climate normalization procedure allows to extrapolate growth simulations throughout locations and seasons; (v) contemplation of all possible water availability conditions (rainfed, and supplementary, deficit, and full irrigations), nutrition regimes, salinity, and capillary raise; (vi) capability to predict crop responses under future climate change; (vii) use of canopy ground cover rather than leaf area index; (viii) presence of both calendar time and thermal time; (ix)  presence of three major types of water-stress responses: canopy expansion, stomatal closure and senescence; (x) addressing planning, management and scenario simulations. AquaCrop distinguishes it self from all other models for its relatively small number of parameters (explicit and mostly intuitive) and an optimum balance between simplicity, accuracy and robustness, addressing mainly practitioner type of end-user such as those working for extension services, governmental agencies, NGOs and various kinds of farmers associations. AquaCrop is also particularly suited for perspective studies involving water use and efficiency in agricultural field crops. Finally, AquaCrop is implemented in a menu-driven, user friendly software programme.