Combinação de fontes de fósforo com diferentes solubilidades no capim-marandu

Abstract

Phosphorus (P) plays a fundamental role in the development of marandu grass, thus, the application of this nutrient directly influences the crop's productivity. Therefore, the objective was the agronomic evaluation of the interaction between P sources in marandu grass. Six experiments were carried out under greenhouse conditions, using clay, medium and sandy textured soil samples. Four sources of P were used, being two commercial sources (triple superphosphate (TSP) and monoammonium phosphate (MAP), and two sources in the research phase (RLT1 and RLT2). The evaluated treatments were: control, TSP, MAP, RLT1, RLT2, TSP + RLT1, TSP + RLT2, MAP + RLT1, MAP + RLT2, (dose equivalent to 150 mg kg-1 P2O5). Three studies were carried out to evaluate the source RLT1 and another three with RLT2 at concentrations of 33.4; 66.6 and 100% in TSP and MAP. The variables analyzed were: Dry mass, P, Ca and Mg contents in the aboveground part of the plant, in addition to the P content (mehlich-1 and Resin extractor), Ca, Mg, H+Al and soil pH. For the source RLT1: the application of P increased the production of dry mass of marandu grass in all studied soils and the accumulated extracted P content (sums of the three crops) in medium textured and sandy soil. The application of RLT1 at a dose of 33.4% in MAP increased the production of dry mass in the 1st crop and accumulated in sandy soil. Increasing doses of RLT1 increased the available levels of P (Mehlich-1 and Resin) in the sandy and clayey soil after three Brachiaria cultivations. For the source RLT2: the application of P increased the production of dry mass and extraction of P in plants in clayey and sandy soil. The application of RLT2 at a dose of 33.4% in MAP increased the P content in plants of the 1st crop in clayey soil and dry mass production in the 1st, 3rd crop and accumulated in medium-textured soil. On the other hand, the application of RLT2 at a dose of 66.6% in TSP increased dry mass production in the 2nd cultivation in sandy soil and phosphorus content (Mehlich-1) after three cultivations in clayey soil. The increase of RLT2 doses increased the P (Resin Extractor) contents in the medium textured and sandy soil after three Brachiaria grass-marandu cultivations.