EFFICIENCY OF N, P AND K USE BY ADULT MACAÚBA PLANTS

The macaúba crop has stood out among the emerging crops due to its great potential for oil production. Little is known about the nutritional demand of the crop, which is essential for the elaboration of tables for recommending correctives and fertilizers. The aim of this study was to evaluate the efficiency of nitrogen (N), phosphorus (P) and potassium (K) use. A forest inventory of 100 macaúba plants was carried out, divided into five age classes (3 and 8 months, 2.1, 5.3 and 9.5 years). Five medium-sized plants, one of each age, were slaughtered, individualizing the different plant compartments (crown, stem, saxophone, root, bunches and fruits) to determine the dry biomass, contents, and nutrient contents. To evaluate the rate of conversion of nutrients into biomass throughout the macaúba growth cycle, the CUB of each plant compartment was estimated by the quotient between the dry biomass and the nutrient content. The efficiency of NPK use for biomass production varied according to the age and compartments of the macaúbas. The CUB values increased as a function of the age of the macaúbas and, in general, the values decreased in the order of P > K > N.