Dimensioning the Impact of Irrigation on Sugarcane Yield in Brazil

Abstract

Water deficit is one of the main causes of sugarcane yield limitation around the world. Sugarcane simulation models can be used to evaluate the impact of irrigation on yield where water deficit causes important losses. The aim of this study was to dimension the potential of irrigation on sugarcane yield in different Brazilian regions, by comparing yields simulated by a calibrated FAO-AZM model under rainfed and irrigated conditions, considering different levels of crop water supply. Simulations were run for 12-month plant cane yield planted every month along the year. Three different soil types with low, medium and high soil water holding capacities were considered for 29 locations in Brazil, considering a 30-year weather data series. Irrigation was applied to cover 20, 40, 60, 80 and 100% of the crop water deficit, with the highest level corresponding to full irrigation to obtain potential yield. The results showed that yield increases depend on the interaction between climate type, weather conditions, soil physical properties, planting date and level of irrigation. The soil with low water holding capacity was the one with the largest response to irrigation. On the coast of Northeastern Brazil, sugarcane planted between March and June was those which were more responsive to irrigation. On the other hand, in the producing regions in the interior of the country, the planting dates with higher responses to irrigation were between October and January. This study proved that irrigation is an important strategy to improve sugarcane yield even in the regions where irrigation is currently not recommended.