Cost defines the type of nitrogen fertilization for coffee trees initial development

إنجليزي. Currently, there are several technologies on the market associated with fertilizers capable of promoting greater effectiveness in the use and availability of nutrients to crops. In coffee growing, the classes of nitrogen fertilizers with increased efficiency stand out. The objective was to evaluate the efficiency of different types of nitrogen fertilizers in the formation of coffee trees and to compare the cost of application. Two experiments were carried out, one in the field in Campos Gerais - MG and the other in a greenhouse at IFSULDEMINAS, Campus Machado. Nitrogen fertilizer technologies were tested: control (without nitrogen application), conventional fertilization, slow release fertilizer and controlled release fertilizer, these in the dosages recommended by the manufacturers. In the experiment in pots, the dose was adjusted according to the volume of soil available to the root system. Height, stem diameter, number of plagiotropic branches, canopy diameter, SPAD index, N content in leaves, number of plants resprouted after frost, shoot and root dry mass and utilization costs were evaluated. There was a difference for crown diameter and SPAD index in the field experiment. In terms of crown diameter, the controlled release treatment remained superior only to the treatment without the addition of N, and, for the SPAD index, the treatment without N was inferior to the other treatments. In the experiment in pots, all the evaluated variables remained superior to the control, except in the dry mass of the roots, where there was no difference. Regarding cost, conventional treatment was the least expensive.

البرتغالية. Several fertilizer-associated technologies are available on the market capable of promoting greater effectiveness in nutrients use and availability to crops. In coffee growing, the classes of nitrogen fertilizers with enhanced efficiency stand out. Hence, this study evaluated the efficiency of different types of nitrogen fertilizers in coffee trees development compared by use cost. We conducted two experiments: one in the field, in Campos Gerais municipality, Minas Gerais, and another in a greenhouse. Aside a control treatment (without nitrogen application), the following nitrogen fertilizer technologies were tested: conventional fertilization, slow-release fertilizer and controlled-release fertilizer, according to manufacturer’s recommendations. In the pots, we adjusted the fertilizer dose according to the volume of soil available to the root system. Height, stem diameter, number of primary branches, crown diameter, soil plant analysis development (SPAD) index, leaf nitrogen (N) content, number of plants regrowing after frost, root and shoot dry mass and use costs were assessed. Results showed a difference for crown diameter and SPAD index in the field experiment. Regarding crown diameter, the controlled-release treatment was superior only to control. As for the SPAD index, control was inferior to all other treatments. In the pots, all the analyzed variables were superior to the control, excepting root dry mass, which showed no difference. In terms of cost, conventional fertilization was the least costly.