IFANSYAH, H. Soil pH and Solubility of Aluminum, Iron, and Phosphorus in Ultisols: the Roles of Humic Acid. JOURNAL OF TROPICAL SOILS, [S. l.], v. 18, n. 3, p. 203–208, 2014. DOI: 10.5400/jts.2013.v18i3.203-208. Disponível em: https://journal.unila.ac.id/index.php/tropicalsoil/article/view/188. Acesso em: 2 aug. 2025.