Aspects of the management of Brachiaria purpurascens on low soils

Francisco Reyes Ocampo
Estación Experimental de Pastos y Forrajes Indio Hatuey, Central España Republicana 44280, Matanzas, Cuba

ABSTRACT
In order to know the effect of planting distance and density, and fertilization on the establishment and the moment to begin exploitation, a study was conducted on the agronomic performance of Brachiaria purpurascens through three trials, on soils that undergo temporary flooding. All the trials were conducted at the Livestock Production Enterprise Aguada, since 1986 until 1991, without irrigation. In trial 1 the effect of densities 1,0; 1,5; 2,0 and 2,5 t of plant material/ha and planting distances 0,60; 0,90 and 1,20 m, was determined. Differences were found in the DM yield (P<0,05), favorable to the 0,60-m distance, which reached the highest percentage of covered area (72,8 %). The effect of the treatments disappeared in the third cutting. In trial 2 (fertilization) the following treatments were evaluated: control, N, P, K, NP, NK, PK and NPK. No significant difference was found among the treatments. The pasture in all the treatments covered more than 75 % of the area and the yield in the control was 4,9 t DM/ha. Experiment 3, which consisted in determining the moment to begin exploitation, started when the pasture had a botanical composition of 40-45, 50-55, 60-65 and 70-75 % after sowing. In the first rotations of the dry season, the area covered by B. purpurascens increased in all the treatments, with significant difference in favor of 70-75 % and a final value of 77,6 %. In the rainy season the area remained flooded until the end of the trial and the percentage of B. purpurascens decreased in all the treatments. The DM availability (1,8 t/ha) was higher for the treatment 70-75 %; while at the end of the period no difference was found for this indicator. It is concluded that under the studied conditions B. purpurascens showed a rapid establishment. The density of 1,5 t of vegetative seed/ha and the distance of 0,60 m were sufficient to achieve a good establishment 120 days after sowing and 1 t of seed was saved with regards to the highest density. It is not necessary to apply fertilizer for its establishment, because the pasture can supply its own requirements through nutrient contributions, saving between $5,00 and $40,96. Grazing should begin when the pasture reaches between 70 and 75 % of covered area, with which the useful life of the pastureland is prolonged.