Resumo

CAMACARO, Selina; GARRIDO, Juan C  e  MACHADO, Wilfre. Nitrogen fixation of Leucaena leucocephala, Gliricidia sepium and Albizia lebbeck and its transfer to the associated grasses. Zootecnia Trop. [online]. 2004, vol.22, n.1, pp.49-70. ISSN 0798-7269.

A study in the experimental field of the Animal Production Institute, Agronomy Department, of the Universidad Central de Venezuela was carried out in order to evaluate the N fixation of Leucaena leucocephala, Gliricidia sepium, and Albizia lebbeck and its transfer to an associate mixed pasture (Cynodon dactylon x Digitaria swazilandensis). Associated plots of 10x2 m were used with two densities (4,000 and 8,000 plants/ha) and grass plots of 4x5 m, fertilized with six nitrogen levels (0, 50, 100, 200, 400 and 800 kg N/ha). A randomized design with three repetitions and 11 treatments was used. The following variables were evaluated: grass dry matter, herbaceous legumes dry matter, dry matter of shrub legumes, edible dry matter, weeds dry matter, nitrogen total yield and fixed and transferred nitrogen. The results obtained in biomass production, yield of N, fixation and transfer of N evidenced that with three shrub legumes is possible to substitute the nitrogen fertilization in a range from 0 to 200 kg N/ha. On the other hand, the sowing density factor had an effect on L. leucocephala only, for fixation and transfer. Also, the ability of A. lebbeck of giving a bigger proportion of the fixed N suggests its potential to be associated with grasses with more demand of N, under the conditions that the experiment was developed.

Palavras-chave : Leucaena leucocephala; Gliricidia sepium; Albizia lebbeck; nitrogen fixation; nitrogen transfer.