Determinações de perdas por volatilização, fixação e lixiviação em fertilizantes especiais

Abstract

The use of organomineral fertilizers presents an innovative alternative for Brazilian agriculture, potentially reducing production costs, preventing nutrient losses, optimizing natural resources that could be discarded and still generate economy. Based on these assumptions, this study aims to compare different types of organomineral and mineral fertilizers in terms of their loss rates and agronomic efficiency. The first experiment consisted of determining the volatilized nitrogen in the form of ammonia after applying various types of nitrogenous fertilizers to the soil. This study was conducted in three different locations: in the greenhouse, in the coffee farm and in the maize cultivation. Treatments were T1-control, T2- organomineral fertilizer (OMF) with organic base in cellulose granules residues 10-10-10, T3-OMF with an organic base in cellulose bran residues 08-08-08, T4- OMF with an organic base in pelletized filter cake residue 10-10 10, T5- OMF with an organic base in filter cake bran residue 10-10-10, T6-mineral fertilizer 18-18-18, T7-polymer-coated mineral fertilizer 15-15-15. In the greenhouse and the coffee farm, the OMF with an organic base from pelletized filter cake residues treatment exhibited the maximum ammonia losses quantified by volatilization. In the maize cultivation experiment, the treatment with OMF with an organic base from filter cake bran residues and OMF with an organic base from cellulose bran residue showed the highest losses rates. The second experiment aimed to evaluate the phosphorus (P) fixation in clayey and medium textured soils with application of different types of phosphate fertilizers and in different dosages. The experiment was conducted in the Umuarama campus laboratory. The experimental design was completely randomized (CRD) with a double 4×4 factorial scheme, with 4 replications. The first factor corresponds to 4 phosphorus sources: 1 - organomineral fertilizer with an organic base from cellulose bran residues 05-26-00; 2 - organomineral fertilizer with an organic base from cellulose granules residues 05-26-00; 3 - polymer-coated mineral and 4 - mineral. The second factor corresponds to 4 doses of P2O5 (0, 200, 400 e 800 kg ha-1 of P2O5). In all used extractors, the higher results of phosphorus availability was shown in treatments with organomineral fertilizer and polymer-coated mineral compared to the conventional mineral fertilizer. With more phosphorus available in the soil solution, there was a lower phosphorus fixation when the organomineral fertilizers and the polymer-coated mineral were used, which demonstrate a physical and chemical protection provided by these fertilizers. The third experiment aimed to analyze the movement dynamics of potassium (K) and phosphorus (P) in the soil profile, considering the soil texture and the source of the applied nutrient. In the PVC columns, six sources of fertilizers were used: 1 - no fertilizer; 2 - KCl, MAP and Urea - mineral 18-18-18; 3 - special nitric and ammonia-based mineral 16-16-16; 4 - KCl, MAP and Urea - polymer-coated mineral 15-15-15; 5 - organomineral fertilizer (OMF) with an organic base in cellulose bran residues, KCl and MAP 10-10-10; and 6 - OMF with an organic base in cellulose granules residues, KCl and MAP 08-08-08. In both soil textures, there was a greater leaching for K in the fertilizer KCl, MAP, Urea - mineral. For P Mehlich-1, at a 10–20 cm depth, the fertilizer with KCl, MAP, urea - mineral obtained the highest content in both studied soils. The P Resin, the highest values in the two studied soil textures, were obtained at a 0-10 cm depth, highlighting the cellulose bran OMF, KCl and MAP. It is concluded that the concentration of K Mehlich-1, P Mehlich-1 and P Resin were higher in sandy soil when compared to clay soil.