A greenhouse experiment was carried out in order to evaluate the effect of P:Mg ratios on content and concentration of B, Cu, Fe, Mn and Zn in alfalfa cultivated in a dystrophic Dark Latosol (Oxisol). The experimental design was a randomized split-plot, with three replicates. Treatments were combinations of P (0, 100, 200 and 400 mg kg-1; source: triple superphosphate) and Mg (0, 100 and 200 mg kg-1; source: magnesium chloride) at the following P:Mg ratios: 0; 0.5; 1; 2 and 4, three harvest were made (sub treatments). Results showed that P:Mg ratios increased total dry matter production in alfalfa. Concentration of Mn and Zn were not affected neither by proportion of P nor by proportion of Mg in soil. Content and concentration of B, Cu, Fe, Mn and Zn in the dry matter of alfalfa varied significantly from first to third cutting.
Effect of phosphorus and magnesium relationship on concentration and content of micronutrients in alfafa/ Efeito da relação fósforo: magnésio no teor e conteúdo dos micronutrientes na alfafa