Efecto de intercalar leguminosas, con diferentes dosis de fósforo sobre el rendimiento de maíz, Zea mays L. en centroamérica
Twenty four similar trials with corn were conducted throughout Central America during 1989 and 1990. The specific objectives were: i) to evaluate the effect of intercropping legumes with corn, ii) to establish P requirements in a system of intercropping corn with legumes, iii) to evaluate soil coverage by the legume as an indicator of a potential for erosion reduction and iv) evaluate weéd control in the intercropped system. The following legumes were tested: Stizolobium deeringianum Bort (mucuna), Vigna unguiculata L. and Canavalia ensiformis L. each one with P doses of 20 and 40 kg/ha. In general, the results obtained in 1989 were similar to those of 1990. The average corn yield for the different locations varied between 1.8 and 6.0 t/ha in 1989 and 1.0 and 5.6 t/ha in 1990, indicating the great environmental variability of the corn zones of Central America. The corn yield was always lower with legumes than without them, at the same rate of P to both years, C. ensiformis reduced the corn yield by 0.310 (±0.32) t/ha, V. unguiculata by 0.540 (±0.48) t/ha and S. deeringianum by 0.610 (±0.69) t/ha. The response to P was variable and depended on the year, the location and the legume. A positive response to P applied to corn without the legume was observed in both years. The was a positive response to P in corn intercropped with.§, deeringianumin 1982 in corn intercropped and with C. ensiformis in 1990. The legume evaluation as a mulch (average of 8 trials) indicate that at 30 days after the corn planting, V. unguiculata gave the best coverage with 62%, followed by C. ensiformis, with 38% and S. deeringianum with 35%.