Water management for sugarcane and corn under future climate scenarios in Brazil

Over the last several decades, there have been concerns worldwide about energy demand. Several alternatives to oil have emerged, among them the use of plant biomass for fuel. Sugarcane (Saccharum spp L.) and corn (Zea mays L.) have exhibited excellent potential in this regard. These crops are highly efficient in producing carbohydrates which can easily be fermented to produce ethanol. Proper irrigation practices, providing the ideal amount of water that the plant needs to reach its full potential yield, are needed to maximize income from these crops. Sugarcane and corn are of great economic importance to the state of São Paulo, where it is common to irrigate these crops. This research aims to determine conditions for increased productivity and water availability for these crops in the region of Piracicaba, SP, under future climate scenarios. To achieve this goal, two crop simulation models presented in DSSAT (Decision Support System for Agrotechnology Transfer), DSSAT/CANEGRO and CERES-MAIZE, were coupled with the MarkSim model for estimating data for current and future (1982-2012 and 2062-2092, respectively) climate scenarios. Information from the Intergovernmental Panel on Climate Change (IPCC) was used to generate data for current conditions, as well as future conditions: the A1B − a middle-term scenario which there are a fast economic growth and balance in the use of sources of fossil and non-fossil fuels; the A2 - a pessimistic scenario which there are a heterogeneous world and an oriented regional economic world; and the B1 - a optimistic scenario which there are local solutions to economic, social and environmental sustainability. Based on these results, for future scenarios, sugarcane cultivar RB86-7515 yield will be reduced by approximately 40% if the cultivars are not genetically improved. To maintain the same yield levels of hybrid corn BR201, these will be necessary to increase irrigation water by 81%.