Crescimento, produtividade e eficiência nutricional de Eucalyptus urophylla em resposta ao manejo de fertilização no Cerrado

Abstract

Although fertilization is an essential activity to obtain attainable productivity, this practice can be quite costly for the forester due to the cost of fertilizers and the operations involved. The use of a higher technological level of fertilizers can reduce eventual losses that occur in the system, such as leaching, volatilization, phosphorus fixation or even reduce fertilization operations, in regions under Cerrado where low fertility is a limiting factor for the productivity. The aim of this work was to compare different nutritional packages, applied in two different forms, single and split dose, evaluating productive and economic aspects and nutritional efficiencies of a plantation of Eucalyptus urophylla in the center-north of Minas Gerais. The soil of the experimental plot is a typical Yellow Oxisol, A moderate, medium sandy texture. The experiment consisted of seven treatments in a banded design with the effects of corrected treatments for rows and columns. It was evaluated up to 71 months of age, with growth and production modeling, leaf area index (LAI), uniformity index (PV 50), biomass quantification and integrated biological utilization coefficient (CBU int) and efficiency of nutrient use. Descriptive analyzes were used to assess trends in the behavior of growth parameters over the years. Tukey's test was used to assess volumetric data, compare biomass and partition nutrient content in compartments, CUBint, and efficiency of nutrient content for trunk, and shoot production. Contrast tests of groups of means were established to compare treatments with NPK fertilization in a single dose and treatments in split doses. No difference was observed in the increment when using the technology MPPA (macromolecular polyphenolic acid) or CSP (superphosphate complex) in phosphate fertilization in subsoiling. During this work, a water deficit was observed in the region, resulting in a loss of productivity of at least 20 m³.ha-1 over the 71 months. The cost of fertilization by volume of wood produced was lower in the MPPA280 + META400SS + META200Cb treatment. The efficiency of use of nutrients from the aerial part for the fertilization groups in single and split doses did not present significant differences. The costs related to the harvest were the same for treatments fertilized with NPK, since their VMI were in the same payment class. Reducing the spread of fertilization is feasible, both in terms of volumetric yield, efficiency in the use of nutrients, and in harvest costs, using the same amount of nutrients and fertilizers from aggregate technology.