Siqueira, J. O., Guedes, G. A., & Ribeiro, M. A. (2014). Availability of the potassium of nephéline sienite from Poços de Caldas, evaluated through successive croppings with corn. Pesquisa Agropecuaria Brasileira, 20(3), 299–307. https://doi.org/10.1590/S1678-3921.pab1985.v20.15124