Monday, November 5, 2007 - 9:50 AM
33-2
AquaCrop - FAO's Crop Water Productivity Software.
The paper presents the robust dynamic crop water productivity model AquaCrop. The model has been developed under the auspices of FAO by an international group of scientists from various disciplines. AquaCrop estimates crop biomass and yield that can be expected under inadequate water availability in a given environment in a particular region. The water content in the root zone is simulated by keeping track of incoming and outgoing water fluxes at its boundaries. When water shortage in the root zone occurs, the canopy development, the transpiration rate, the biomass production and the yield formation are slowed by a number of mechanisms. Leaf growth and therefore canopy development is reduced when the water status in the soil drops only slightly below its optimum. When water stress becomes more severe, transpiration is directly affected by stomatal closure. Under severe water stress conditions, leaf and canopy senescence are triggered, thereby reducing the transpiring foliage area. The above mechanisms of crop response to cope with water shortage are described in the model by only a few parameters. By means of a water production function and a harvest index the simulated transpiration rate is directly converted into biomass, fruit and grains. AquaCrop is a menu-driven programme. A set of files describe the environment in which the crop will develop. The files contain weather data (Temperature, Reference evapotranspiration, and Rainfall data), and Crop, Soil and Field Management characteristics. New environments are created by specifying a few variables with which the program will generate indicative values for the required crop and soil parameters. Values can always be adjusted if the user has more detailed or site-specific information. A multiple of figures, visualising all kind of crop and soil characteristics, are helpful to realize the consequences of changes in the input. With the help of graphs which are updated every time step (day) during the simulation run, the user can keep track of the simulated canopy development, the evapotranspiration rate and changes in the soil water content. The model will be useful to asses the effect of alterations in the environment on crop development, to develop irrigation strategies under water deficient conditions, and to simulate yields one can expect in a particular soil-field-crop-atmosphere environment.
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