Modelagem da perda acumulada de nitrogênio por volatilização na adubação de cobertura em plantas de milho

Abstract

Corn cultivation is one of the most important in the world, with 70% of global production destined for animal feed and 30% for human consumption, bioenergy production, chemical and pharmaceutical products. To increase productivity, it is necessary to supply essential nutrients, such as nitrogen (N), phosphorus (P) and potassium (K), which are often scarce in corn production. Urea has a high concentration of nitrogen, which is important for corn crops, is easily handled and has a lower cost per kilogram of nitrogen, but it presents high losses of this nutrient due to volatilization. Therefore, technologies are developed that aim to minimize these losses, the most widespread of which is N-butyl thiophosphoric triamide (NBPT). The accumulated losses of nitrogen by volatilization from Urea in kgha-1 present a sigmoidal pattern, therefore, non-linear models are recommended for describing the data. This work aims to select the most appropriate non-linear model to describe the accumulated loss of nitrogen due to volatilization of Urea fertilizers with increased efficiency with NBPT applied in top dressing in corn plants. The data analyzed are recipes from Fonseca (2021) and require the accumulated loss due to volatilization of fertilizers: Granulated Urea (UGRAN), Urea + NBPT + NPPT (UNBPT1), Urea + NBPT Adduct (UNBPT2), Urea + NBPT (UNBPT3), Urea + NBPT (NBPT4). The assumptions of normality, homoscedasticity and residual independence were evaluated using the Shapiro-Wilk, Breusch-Pagan and Durbin-Watson tests, respectively. The models were adjusted by the iterative Gaus-Newton method using the R software. The quality of the fit was evaluated based on the values of the adjusted coefficient of determination (Raj2), the Akaike information draws (AIC) and the standard deviation residual (DPR). The von Bertalanffy Model was the one that best fitted the data for pure Urea (UGRAN) and Urea + NBPT2 (UNBPT2) fertilizers, while the Gompertz model best fitted the data for the fertilizers Urea + NBPT1 (UNBPT1), Urea + NBPT3 (UNBPT3) and Urea + NBPT4 (UNBPT4). The UGRAN fertilizer showed a greater accumulated loss with an estimate of 36.503 kg ha-1 while the UNBPT4 fertilizer recorded a smaller loss with an estimate of 14.623 kg ha-1 which corresponds to a reduction of 59.9% in relation to pure Urea. Urea constituted with NBPT delayed the accumulated loss of nitrogen by volatilization.