Forecast sugarcane maturity from agrometeorological data and soil water storage

Abstract

The environment (climate and soil) can stimulate the accumulation of sugars in the cane, inducing the plant´s maturation process. In this way, we can estimate sugarcane maturity based on the crop's growth response to environmental conditions, which allows us to quantify the raw material (ethanol or sugar) and plan the harvest. The aim of this study was to evaluate the effects of agrometeorological variables and soil water storage on the sugarcane maturation process and to generate forecasting models for soluble solids content (°Brix) and total recoverable sugars (TRS, kg t-1). The experiment was carried out in the Santo Antonio de Goiás, Brazil. We evaluated °Brix and TRS of the sugarcane cycles (cane-plant, 1st ratoon, 2nd ratoon). The agrometeorological data was obtained from a weather station, which made it possible to calculate the crop’s water balance and degree-day. All the variables were subjected to multivariate statistical analysis, which selected the most significant variables. The models used degree-days, reference evapotranspiration and soil water storage as independent variables, which obtained multiple coefficients of determination (R_p^2) greater than 0.60. The estimates showed a good fit for both °Brix and TRS models, which determined a mean absolute error (MAE) of 1.15 °Brix and 9.88 kg t-1, respectively; and very good confidence index (c > 0.75). Independent estimates obtained MAE < 2.60 ºBrix, while TRS resulted in MAE < 21.30 kg t 1, with “c” ranging from good to optimum (c > 0.70). Models based on multivariate analysis can be used to estimate the sugarcane harvest point based on the sugar content in the stalks, agrometeorological variables and soil water storage.