Abstract 131

Jones,RJ

Div. Trop. Crops and Pastures, CSIRO, Aikenvale, Qld 4814, Australia.

Tropical-Grasslands. 1989, 23: 2, 65-74; 12 ref.

Pastures of Setaria sphacelata var. sericea cv. Narok and of Chloris gayana cv. Samford at Samford fertilized annually with 250 kg single superphosphate, 125 kg KCl and 336 kg N/ha were compared at a set stocking rate of 5 steers/ha over a 4-year period. Pastures of Narok gave higher yields of total pasture DM and of green DM on most sampling occasions. The N, P and K concn in the yield on offer were similar for both pastures, although N in Samford was higher than for Narok in summer/autumn. Over this period, however, samples plucked to simulate herbage grazed by cattle were significantly higher in N and K for the Narok pastures. Faecal N levels were also higher for steers grazing Narok throughout the year. Plucked pasture samples of Narok in spring, summer and autumn were higher in N, K, Na and Zn whereas those of Samford were higher in Ca and S. Despite differences in yield and mineral concn the pattern of liveweight gain of steers was similar for both pastures in 3 of the 4 years although Narok tended to give reduced liveweight loss in winter and spring with Samford giving better liveweight gain in summer/autumn. The marked superiority of Narok over the winter/spring period of 1970 was associated with an exceptionally cold winter which retarded the spring growth of Samford. However, annual liveweight gains did not differ significantly in any year. Mean annual gains were 160 and 159 kg/head for Narok and Samford, resp.