Animal production on sown and native pastures on brigalow land in southern Queensland during drought

Abstract

Liveweight gains of six yearling steers grazing on each of four introduced grasses, each with lucerne, were compared with those from native pasture and native pasture plus forage oats, on a weakly solonized brown clay loam of moderate fertility in the brigalow region of southern Queensland. The pastures were grazed continuously for three years (1963 to 1965) at set stocking rates during the worst drought known from 87 years of local records. At the height of the drought in 1965 the sown pastures supported animals as far into the drought as did the two native pasture treatments at half the stocking rate. Sorghum almum (CV. Crooble) and Rhodes grass (Chloris gayana CV. Pioneer) died late in the drought and did not re-establish after rain, whereas buffel grass (Cenchrus ciliaris CV. Nunbank) and green panic (Panicm maximum var. trichoglume CV. Petrie) survived. Standing dry matter in the pastures was less than 1,000 lb dry matter an acre for much of the life of the experiment. At a stocking rate of one bullock to 2.3 acres S. almm gave the highest average gain per head in the first full year of grazing (462 lb per head), but this was only significantly better (P<0.05) than the gain from buffel grass, and not significantly better than the gains (at one bullock to 4.6 acres) on native pasture (415 lb per head) and native pasture plus oats (390 lb per head). Rainfall in the first year was 18 inches. In the remaining two years, with 13 and 8 inches of rain respectively, there were no significant differences between the sown pastures until the S. almum and Rhodes grass died. Native pasture plus oats (681 lb per head) and native pasture (424 Ib per head) gave the greatest gain per head in 1964, but not per acre because of the lower stocking rate.