Abstract 585

Gutteridge,-RC; Shelton,-HM; Wilaipon,-B; Humphreys,-LR

Dep. of Agric., Queensland Univ., St. Lucia, Qld. 4067, Australia.

Tropical-Grasslands. 1983, 17: 3, 105-114; 23 ref.

Cattle liveweight gains were compared during 1976-80 on native bamboo grass (Arundinaria spp.), improved pasture consisting of bamboo grass oversown with Stylosanthes humilis cv. Lawson and S. hamata cv. Verano and a fully improved pasture mixture of Brachiaria decumbens cv. Basilisk, Urochloa mosambicensis, Macroptilium atropurpureum cv. Siratro and S. hamata cv. Verano. Fertilizer treatments consisted of application of 30 kg P and 30 kg S/ha. The legume content of the pastures declined to 4% by the end of the experiment due to competition from the bamboo grass; botanical composition was unaffected by stocking rate or fertilizer application. Mean liveweight gain at the lowest stocking rate of 1.1 yearlings/ha was 33 kg/head yr. In one 11 month period of salt supplementation, liveweight gain on bamboo grass was 97 kg/head compared with 42 kg/head without supplementation. The wet season presentation yields of fully improved pasture by 1980 were 4710 and 9100 kg/ha at 4.3 and 2.1 yearlings/ha resp. At the highest stocking rate the pasture was overgrazed during the dry season resulting in a reduction in sown grass and an increase in weed content. The dry season levels of N in the grasses and P, S and Na in all spp. were below established critical levels for cattle maintenance.