78 J. PACD – 2004 Compositional Nutrient Diagnosis In Nopal (Opuntia ficus-indica) ♦ Rafael Magallanes-Quintanar 1 , Ricardo David Valdez-Cepeda 2 , Fidel Blanco-Macías 2 , Miguel Márquez-Madrid 2 , Raúl René Ruíz-Garduño 2 , Oscar Pérez-Veyna 3 , José Luis García-Hernández 4 , Bernardo Murillo-Amador 4 , José Dimas López-Martínez 5 , and Enrique Martínez-Rubín de Celis 6 1 Universidad Autónoma de Zacatecas, Unidad Académica de Medicina Veterinaria y Zootecnia, Programa de Doctorado en Ciencias Pecuarias. Apdo. Postal 11, CP 98500, Calera de V.R., Zacatecas, México 2 Universidad Autónoma Chapingo, Centro Regional Universitario Centro-Norte, MCDRR. Apdo. Postal 196, CP 98001, Zacatecas, Zac. México Fax No. +52 492 9246147. E-mail: vacrida@hotmail.com Guest Researcher at the Universidad Autónoma de Zacatecas, Unidad Académica de Matemáticas. Calzada Solidaridad s/n, esquina con carretera a La Bufa. Zacatecas, Zac., México 3 Universidad Autónoma de Zacatecas, Centro Universitario de Cómputo. Ramón López Velarde # 707, interior D. CP 98064, Zacatecas, Zac. México 4 Centro de Investigaciones Biológicas del Noroeste, S.C. Apdo. Postal 128, CP 23090, La Paz, B.C.S., México 5 Facultad de Agricultura y Zootecnia, Universidad Juárez del Estado de Durango. Apdo. Postal 142, CP 35000, Gómez Palacio, Dgo., México 6 Instituto Tecnológico Agropecuario de la Laguna. Apdo. Postal 3-F, CP 3500, Torreón, Coah., México ABSTRACT The appraisal of soil fertility and the assessment of plant mineral requirements are fundamental for crop management. This study was conducted to determine nutrient norms and to identify significant nutrient interactions in nopal (Opuntia ficus-indica). Preliminary compositional nutrient diagnosis (CND) norms were developed from a small database as means and standard deviations of row-centered log ratios (Vx) of five nutrients (N, P, K, Ca, and Mg) and a filling value, R, which comprises all nutrients not chemically analyzed and quantified in nopal plants. Preliminary CND norms are: * N V = -1.13336 ±0.0766, * P V = -2.26110 ±0.1093, * K V = 0.36715 ±0.2329, * Ca V = 0.37021 ±0.1047, * Mg V = -0.7257 ±0.1413, and * 5 R V = 3.38281 ±0.0833. These norms qualify yields higher than 35 kg pl -1 (fresh matter of cladodes one- year old) registered in an experimental plot with a plant density of 10000 plants per hectare, and are associated to 0.97% N, 0.31% P, 4.47% K, 4.37% Ca, and 1.47% Mg. Four important nutrient interactions were evidenced through principal component analyses: Ca-Mg, Ca-N, Mg-N, and K-P. Key Words: compositional nutrient diagnosis approach; nutrient interactions; nutrient norms ♦ Received 29 November 2004