Title: AquaCrop (FAO crop water productivity model) as a tool to assess the consequences of climate change on crop development and the soil water balance
Authors: Vanuytrecht, Eline ×
Geerts, Sam
Willems, Patrick
Raes, Dirk #
Issue Date: Jun-2009
Publisher: Royal Academy for overseas sciences
Host Document: Abstracts International Symposium of The Royal Academy for overseas sciences and The United Nations. 'Developing countries facing global warming: a post-Kyoto Assessment' pages:82-83
Conference: International Symposium of The Royal Academy for overseas sciences and The United Nations. 'Developing countries facing global warming: a post-Kyoto Assessment' location:Brussel date:12-13 June 2009
Abstract: Predictions mention an increase in atmospheric CO2 concentration of 2 ppm per year in the
coming decade. If extrapolated, this will bring the global atmospheric CO2 concentration near
to 600 ppm in 2100. This aspect of climate change, together with raised air temperatures and
altered rainfall patterns, affects crop development and production and can impose great
challenges for the food security in developing countries. As a logical consequence of the
direct influence on crop development and more specifically on crop transpiration, climate
change also has an impact on the soil water balance, which might result in an increased risk of
droughts and floods. The way to adjust crop modelling for the influence of increased CO2
concentrations on crop growth and crop transpiration in order to determine the effect on crop
production and the soil water balance is presented in this poster. The effect of raised CO2
concentrations will then supplement the influence of the other climatic parameters
(temperature, rainfall and radiation) on crop development and transpiration.
AquaCrop, the recently released crop water productivity model of FAO, can act as an
appropriate model to analyze the effect of climate change on crop production and the soil
water balance. Although AquaCrop founds its simulations on complex bio-physical processes,
it only requires limited, readily available input data about climate, crop, soil and management,
which facilitates its application in developing countries. The model combines accuracy,
simplicity and robustness and is highly user-friendly. Since AquaCrop is calibrated and
validated for many commonly cultivated crops by FAO, the model is applicable all over the
world and can serve to predict yields, assess soil water balances and design irrigation
schedules. The core growth equation in AquaCrop links biomass (B, in kg) to crop
transpiration (Tr, in mm) through the crop water productivity (WP, in kg per m² and per mm
of cumulated water transpired): B = WP · ΣTr. The water productivity is considered to be
conservative if normalized for the atmospheric CO2 concentration. In an attempt to
incorporate the additional effect of elevated CO2 on the crop transpiration and canopy
expansion (expressed by means of a canopy growth coefficient in AquaCrop), a thorough
review of more than eighty peer-reviewed articles about free-air CO2 enrichment (FACE)
experiments in different parts of the world was carried out.
The comparison of crop development and biomass production of crops grown under ambient
and elevated CO2 concentrations in these open-air experiments (FACE) showed evidence of
the influence of raised CO2 concentrations on both the crop transpiration and the canopy
growth coefficient. While keeping in mind the established knowledge about enhanced water
productivity, minor increases in biomass production under elevated CO2 concentrations were
observed. This could be attributed to reduced transpiration when crops close their stomata.
Evidence about the altered crop growth curve came from a detailed comparison of canopy
cover evolution, mainly expressed as the evolution of the leaf area index in the articles. Rising
CO2 concentrations cause the canopy to reach its maximum faster and thus increase the
canopy growth coefficient.
Raised CO2 concentrations increase crop water productivity, diminish crop transpiration and
accelerate crop growth, which involves consequences for crop production and the soil water
balance. The incorporation of the CO2 effect on crop development and biomass production
makes AquaCrop, suitable to predict and analyze risks related to food security, droughts and
floods in developing countries.
Publication status: published
KU Leuven publication type: IMa
Appears in Collections:Department of Civil Engineering - miscellaneous
Division Soil and Water Management
× corresponding author
# (joint) last author

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