Uso de adubos de liberação lenta no crescimento inicial de clones de eucalipto

Abstract

The nutrient management in eucalyptus plantations it is a key practice, in this way, consistent efforts are necessary to optimize the use of nutriente. In this context, the objective of this work was to evaluate the adequate doses of slow release fertilizer (SRF), in comparison to the application of simple superphosphate (SPS) in the base fertilization (BF) and its impact on the need for top dressing (TD) in seedlings of a eucalyptus hybrid, grown in pots.The experiment was arranged in a randomized block design in a 6x3 factorial scheme, in which the first factor corresponds to six doses of AB (0, 50, 75, 100, 125% of P) of SRF and 100% of P, of simple superphosphate (SPS). The second factor corresponded to three CF applications (0, 1 and 2 portions of KCl and NH4NH3. The doses of N, P, K were based on the recommendation of fertilization in pots of 300, 100 and 100 mg dm-³, respectively at 120 days, height (H), stem diameter (D), leaf area (LA), number of leaves (NL), plant dry mass were evaluated. In addition, doses of maximum technical efficiency were calculated (DMTE). The averages obtained by BF with SLF, of all variables were higher than the SPS. For the H, it is recommended to use one CF, with a DMET of 252.56 mg dm-³, of P, for having obtained growth similar to SPS. For the other variables, DMTE for BF, ranged from 236.52 to 327 mg dm-³, of P. In relation to CF, the, D, NL and shoot dry mass, did not show differences significant, which evidences the quality of the fertilizer in supplying the nutrients supplied in the CF, enabling its reduction. Thus, the DMTE indicated for plantings of the species is 100% ALL, guaranteeing satisfactory initial growth and use of only one CF.