Modelagem da perda de nitrogênio por volatilização de amônia em fertilizantes aplicados no cafeeiro

Abstract

Nitrogen (N) is a mineral nutrient, found in a variety of forms in the soil, it can be absorbed in different ways by growing plants, important in the process of photosynthesis and for the production of proteins in crops. Coffee is a plant that has a dependence relationship with nitrogen, given its nutritional relevance for productivity. However, the nutrient is not fully absorbed from the soil by the plant, thus, the need for complementation via fertilization arises. However, this nitrogen fertilizer applied to coffee crops can be lost by volatilization of ammonia (NH3). Knowledge of the nutritional behavior of coffee crops contributes to proper management, influencing quality, productivity and minimizing economic losses. For this reason, in this work, the objective was to select the most adequate nonlinear regression model to describe the nitrogen losses, by volatilization of ammonia (NH3), in seven conventional and increased efficiency fertilizers applied in three installments in the coffee tree. The data evaluated, regarding the loss of N, originate from an experiment carried out during the 2015/2016 harvest, at the Coffee Innovation Agency (INOVACAFÉ) of the Federal University of Lavras, in a randomized block design with 3 replications of 7 treatments (fertilizers nitrogenous). The estimation method used was the least squares method (MMQ), having the Gauss-Newton convergence algorithm as the iterative method. In addition, all analyzes of the work were performed using the free software R. Through the results found by the quality of fit evaluators: adjusted coefficient of determination (R2a j), residual standard deviation (DPR), criterion of information of Akaike (AIC) and mean absolute deviation (DMA) we found that all models showed good fits, however, the Brody model showed the best fits to describe the accumulated losses of nitrogen, by volatilization of ammonia, in relation to the seven treatments applied and evaluated.