This report aims to synthesize the results of a crop water use study conducted by country teams of the GEF/World Bank project, Regional Climate, Water, and Agriculture: Impacts on and Adaptation of Agro-ecological Systems in Africa. It also presents the results of the second phase of the study based on climate change scenarios, conducted by the South Africa country team. The actual evapotranspiration of five commonly grown crops-maize, millet, sorghum, groundnuts, and beansin two selected

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... cts were analyzed by six country teams. In addition, two country teams also analyzed other crops grown in the districts. The regional analysis shows that the actual yield of the different crops-specifically of maize and groundnuts-improves with an increase in actual evapotranspiration, although the gap remains wide between actual and potential yield and actual and maximum evapotranspiration, especially for the rainfed crops. This highlights the importance of improved water management if agriculture is to play an important role as a source of food security and better livelihoods. The report highlights the vulnerability of maize to water stress and the increased risks to the viability of rainfed farming systems based on this crop. The results of the second phase of analysis show that a 2°C increase in the temperature and a doubling of carbon dioxide concentration in the atmosphere will shorten the growing period of maize, which will result in decreased crop water requirement and use. The authors recommend extending this type of analysis to other crops as well as to other countries to develop a clearer picture of the changing pattern in crop water use of the major crops grown in the project countries. SUMMARY This report aims to synthesize the results of a crop water use study conducted by country teams of the GEF/World Bank project Regional Climate, Water and Agriculture: Impacts on and Adaptation of Agro-ecological Systems in Africa. It also presents the results of the second phase of the study based on climate change scenarios, conducted by the South Africa country team. The actual evapotranspiration of five commonly grown crops -maize, millet, sorghum, groundnuts and beans -in two selected districts were analyzed by six country teams. In addition, two country teams also analyzed other crops grown in the districts. The regional analysis shows that the actual yield of the different crops -specifically of maize and groundnuts -improves with an increase in actual evapotranspiration, although the gap remains wide between actual and potential yield and actual and maximum evapotranspiration, especially for the rainfed crops. This highlights the importance of improved water management if agriculture is to play an important role as a source of food security and better livelihoods. In general, the study results give realistic evapotranspiration and actual yield values for maize, sorghum, millet, beans and groundnuts. The average values for crop water productivity for these crops are within the common published ranges, with maize and sorghum being the most water efficient crops in terms of water use. It is important, however, to highlight the vulnerability of maize to water stress and the increased risks to the viability of rainfed farming systems based on this crop. The first phase of the study provided a framework for the analysis of future crop water use as affected by climate change in Africa. The second phase of the analysis, that includes climate change impact on crop water use, was conducted by the South Africa country team. This analysis was performed for maize, using the methodology developed by the FAO (Food and Agriculture Organization) that is used together with CROPWAT to assess future crop water requirement and use. The results of the second phase of analysis show that a 2°C increase in the temperature and a doubling of CO 2 concentration in the atmosphere will shorten the growing period of maize, which will result in decreased crop water requirement and use.