The objective of this work was to evaluate the efficiency of six extractants and the effect of boron concentration and dry matter yield, cultivated in greenhouse conditions with two Rhodic Hapludox in Mauá da Serra and Londrina, in the State of Paraná, and one Ustoxix Quatzipsamment in Alto Garças, State of Mato Grosso, Brazil. The experiment was conducted in a completely randomized design with six boron rates (0, 0.25, 0.5, 1, 2 and 4 kg ha-1), and three replicates. The available boron was determined with six extractant solutions: Mehlich 1, Mehlich 3, hot water, HCl 0.05 mol L-1, Ca(H2PO4)2.H2 O 0.01 mol L-1 and KCl 1.0 mol L-1. The results showed that the B extracted by hot water had the best correlation with the dry matter yield and B content in the plant, whereas the KCl 1.0 mol L-1 was the most efficient in the determination of B level in dry matter. High concentrations of B diminished the efficiency of the hot water extractant in determining the B available in soil. The highest correlations were obtained between the extractant Mehlich 1 and Ca(H2PO4)2.H2 O 0.01 mol L-1, KCl 1.0 mol L-1 and HCl 0.05 mol L-1, KCl 1.0 mol L-1 and Ca(H2PO4 )2.H2O 0.01 mol L-1, and hot water and Ca(H2PO4)2.H2 O 0.01 mol L-1.
Glycine max; methods of soil analysis; micronutrient; nutrient availability
