INTERAÇÃO BIOCHAR E ADUBAÇÃO NA NUTRIÇÃO E CRESCIMENTO INICIAL DE ERVA MATE (Ilex paraguariensis A. ST. HIL)

Abstract

This study aimed to study the effects of NPK mineral fertilization associated with doses of biochar (0, 10, 30 and 50% mixed with soil) on the initial growth and nutritional status of yerba mate (Ilex paraguariensis A. St. Hil.). The biochar was obtained from the pyrolysis of a mixture of pine and eucalyptus residues from wood industries of the region. Measurements of stem diameter and shoot height were taken at 0, 60, 120 and 180 days after planting. In the end, the plants were harvested, and the production of shoot and root biomass was evaluated. Foliar contents of macronutrients (N, P, K, Ca, Mg and S), micronutrients (Mn, B, Mo, Zn, Cu, Ni and Fe), beneficial elements (Al, Si, Se, V and Na) and contaminants (Cd, Cr and Pb) were determined. NPK mineral fertilization at planting was essential for adequate growth of yerba mate. On the other hand, there were no positive effects of biochar on the yerba mate growth, regardless of fertilization. The 10% biochar dose did not affect plant growth; however, doses of 30 and 50% caused toxicity. Foliar contents of K, Ca, Mg, S, B and Mo were increased with biochar doses, while foliar content of Mn was decreased. Also, biochar doses reduced foliar Al and Cd contents. Thus, the biochar used in this experiment, at least in the short term, does not replace mineral fertilization, even partially, for adequate initial growth of yerba mate. However, its use in dosages up to 10%, aiming at soil conditioning, does not harm the development of yerba mate and has the potential to increase foliar contents of some nutrients and reduce foliar Cd content.