The yields of four tropical grass/legume pasture mixtures were studied over a 4-year period. These mixtures had the following composition: H, Cynodon nlemfuensis var. robustus, together with the legumes Centrosema pubescens (Benth.), and Stylosanthes gracilis (H.B.K.); J, Pennisetum purpureum (Schum.) plus the two legumes in H; K, treatment J mixture plus Panicum maximum (Jacq.); and L, a mixture of treatments H, J and K. Each treatment paddock was grazed in rotation between 19 April 1966 and 21 November 1969.
The mean annual dry-matter yields over the 4 years of grazing were approximately 37 ± 5·7, 41 ± 2·6, 44 ± 10·2 and 47 ± 8·7 t/ha for treatments H, J, K and L respectively. The overall mean for the four treatments was 42 ± 5·1 t/ha/annum.
It was observed that the dry-matter yield of the three mixtures in J, K and L, containing the tall grass species, was significantly superior to that of treatment H; however, they were not statistically different among themselves.
After the second year of grazing Stylosanthes gracilis diminished gradually and it was almost absent from the swards by the final year of grazing, while Centrosema pubescens maintained its stand throughout the experimental period.
With the exception of phosphorus and sodium, levels of mineral elements in the pastures were above the recommended allowances for various classes of livestock.
The average level of zinc was only slightly below the recommended value.