HUNSAKER-ALCÂNTARA, H. M.; JOLLEY, V. D.; WEBB, B. L.; ALLEN, P. S.; HORROCKS, R.; CORONEL, E. G.; BUESO C., M. L. Alternatives to the Mehlich-I extraction method to estimate the P requirements in guatemalan soils. Agronomía Tropical, v. 60, n. 1, p. 23-33, 30 Mar. 2010.