Forma de aplicação de níquel, cobalto e molibdênio em sistema plantio direto na cultura da soja

Abstract

The use of micronutrients for the process of biological nitrogen fixation is a practice that is embedded in the nutritional management of soybean. With the inclusion of nickel in the list of nutrients, works have being made to identify the position most suitable for the delivery of these and other nutrients involved in the process. Thus, the objectives of this study were to identify the form of application and doses of nickel, cobalt and molybdenum in no-tillage system, evaluate the effect on productive traits of soybean and establish standards of reference DRIS for the culture of soybean in areas of three and 15 years of direct planting. The experiments were implanted in areas of three and 15 years of no-tillage system in the Federal Institute of Triângulo Mineiro (IFTM), Campus Uberaba, Minas Gerais state, with an altitude of 795 m in the period from December 2015 to April 2016. The leave’s nourishment was made in doses of 140, 200, 240 and 280 g ha-1 with a foliar fertilizer based on nickel, cobalt and molybdenum. The foliar sampling and establishment of indices DRIS were made through the collection of the first ripe leaf from the upper leaflets, held in the phenological stage R1. We calculated the index of nutritional balance (IBN) by the sum, in module, for nutritional indices DRIS and the index of nutritional balance medium (IBNm). For the interpretation of nutritional status, were adopted three classes: insufficient, balanced or surplus. The harvesting of grain were made per plot, estimating the yields in t ha-1. The data from each of the individual test, for the two systems of direct planting, were subjected to analysis of variance and then there was the similarity of the mean squares of the residue and the ratio between the highest and the lowest mean square was residual with less than seven, allowing the joint analysis, providing information to determine the dose of NiCoMo to be used in soybean crop. The application of micronutrients in the treatment of vegetation provides greater nutritional balance of plants under no-tillage system for three years, and the dose of 280 g ha-1 of nickel, cobalt and molybdenum in the treatment of vegetation resulted in higher grain yield of soybean. The dosages of 200 and 280 g ha-1 of NiCoMo on treatment of seeds and vegetative, respectively, provide greater grain yield and plant more nutritionally balanced in direct planting at 15 years. Soybean yield is dependent on factors such as diseases, climatic conditions, type of cultivation and sowing time.