Perdas por volatilização de N-NH3 e avaliação de fertilizantes nitrogenados contendo micronutrientes na cultura do milho (Zea mays)

Abstract

This study aimed to evaluate the dynamics of nitrogen losses by volatilization of ammonia from urea fertilizers pelletized with different micronutrients (zinc, copper and boron), and to evaluate possible residual effect of these nutrients as well as the effect on the growth and development of corn (Zea mays) plants. The studies took place in a greenhouse at the experimental area of the Soils Department of Federal Rural University of Rio de Janeiro. The soil used in this study was sampled from surface horizon of a Fragiudult soil and had sandy texture. For testing volatilization and residual effect of nitrogen two doses (100 and 200 kg ha-1) were applied. The fertilizers were evaluated for N losses for a period of 21 days. After the period of the N losses evaluation, corn seeds were planted in the same soil, to assess the residual effect of these pelletized fertilizer containing micronutrients. After these two experiments, they were selected, among the 15 pelletized urea formulas, 9 products that showed the best results, especially those which resulted in decreasing N losses by volatilization. These products were then evaluated for their effect on growth and development of corn plants, using the variety Sol da Manhã. The amount of the micronutrient boron in the pelletized urea positively influenced the reduction of N losses by NH3 volatilization, particularly when in higher concentration (4.0% B), reducing N losses by 50% (rate of 100 kg ha-1) and 64 % (dose of 200 kg ha-1) compared to the pearly urea. In general, the pelletized urea containing micronutrients, especially B, single or associated with Zn and Cu, showed to be a promising alternative for new fertilizers, with the goal of reducingN losses by volatilization. There was no effect of the different nitrogen fertilizers application as for increasing residual N in the soil. The application of the pelletized urea containing Zn, Cu and B micronutrients, single and / or associated, increased their quantities in the soil. The largest additions of the micronutrients Zn, Cu and B in the soil, using the pelletized urea, consequently, reflected in greatest amounts of these elements in the maize plant. The addition of zinc by application of pelletized urea did not show positive effect in the growth of corn plant as expected. Possibly, due to zinc quantities in the soil sufficient to supply the plants requirement. The presence of boron in the pelletized urea influenced the accumulation of N in the plants, especially for B concentrations in the fertilizer above 2.0 %.