Assessing soil key fertility attributes using a portable X-ray fluorescence: A simple method to overcome matrix effect - Tavares, Tiago Rodrigues; Mouazen, A. M; Alves, Elton Eduardo Novais; Santos, F. R. dos; Melquiades, F. L; Carvalho, Hudson Wallace Pereira de; Molin, Jose Paulo (Agronomy, 2020)