Produtividade da cana-de-açúcar em função de probabilidade climática em Alagoas

Abstract

The Brazilian Northeast is characterized by an irregular spatial and temporal distribution of rainfall. Additionally, in the coastal zone of this region, the factor that most influences the productivity of agricultural crops is the alternation between dry and wet periods. Sugarcane evapotranspiration is severely affected by the seasonality of rainfall, since, in order to achieve productive yields with economic returns, sugarcane requires, on average, between 1,500 and 2,500 mm of water, evenly distributed throughout the year.In this context, the objective was to analyze the relationship between water deficit and sugarcane productivity, comparing it with irrigated conditions. Using the climatological normals from the last 35 years (1988–2023), the expected distribution of the climatic elements of precipitation and reference evapotranspiration was determined for the 10th, 25th, 50th, 75th, 80th, 90th, and 95th percentiles of probability of occurrence.The monthly water balance was calculated using the method described by Thornthwaite-Mather (1955), considering 12 planting and harvesting scenarios for plant cane, combined with six irrigation scenarios for the 2016 to 2023 harvest seasons.Using the Doorenbos and Kassam model (FAO 33), crop productivity was estimated, and productivity losses were determined for the harvests that took place from 2016 to 2023. Finally, the best management scenarios for sugarcane cultivation were identified.Plantings carried out in March with harvesting in February showed the highest average water deficits during the summer cultivation, while the lowest losses occurred between December and November, with the exception of the 4.5 mm drip irrigation management. In winter cultivation, plantings in May with harvesting in April showed the highest average productivity losses, while the lowest losses were recorded for the planting also carried out in May with harvesting in April. Keywords: Water balance; Climatic conditions; Irrigation scenarios.