Impacts of Climate Change on Soybean Irrigation Water Requirements inNorthwest Region of Rio Grande do Sul, Brazil

Higher temperatures and a larger variability in precipitation will cause, in general, higher irrigation water requirements. The most important non-irrigated crops for the economy of the state of Rio Grande do Sul, Brazil, are corn and soybeans and the mesoregion which most contributes to the annual harvests of these crops is the Northwest region. This article aims to assess whether the impacts of climate change on agriculture in this region will be positive or negative and in what intensity they may occur. Hence, data from future climate projections generated by different climate models, as well as soil sampling for characterizing physical and hydraulic soil properties were considered. The one-dimensional SWAP model was used to estimate the irrigation water requirements. The results of the hypothesis tests performed for all simulations supports the premise that the irrigation water requirements in the near future (2025s) are not statistically different from the baseline period (1960-1990). On the other hand, water irrigation requirements in 2055s and 2085s reject this hypothesis.