Abstract:
Proc. Aust. Soc. Anim. Prod. Vol. 18 CATTLE GROWTH RESPONSES TO SOIL PHOSPHORUS, STYLO AND PHOSPHORUS SUPPLEMENT C.P. MILLER* and C.D. WEBB* Growth of cattle grazing native pastures in seasonally dry north-eastern Australia has previously been shown to be sensitive to soil phosphorus (P), legume augmentation and P supplement (Miller and Webb 1988). This report gives early results from a more comprehensive study of the relationships between soil P, legume and P supplement. Three two-year-old steers in each paddock continuously grazed native pastures oversown with the legumes Seca and Verano stylo under a eucalypt woodland at 0.25 steers/ha. -There were three fertilizer treatments each with and without supplement and an additional two fertilizer treatments with supplement, each Superphosphate was applied to maintain soil P at levels above the duplicated. natural level of 2 ppa bicarbonate-extractable P. Supplement was supplied year round as a dry lick of monoammonium phosphate to give a daily intake of 5 g There was at all times at least 4000 kg/steer of native pasture dry P/steer. matter in all paddocks. Table 1 Effects of soil P level, legume availability and P supplementation on steer liveweight change (1988-89) Dry season liveweight change was correlated strongly with legume availability (r=0.90, P<O.Ol), while P supplement had no significant effect. Liveweight gain in the following wet season was increased by P supplement but legume availability had no significant effect. We conclude that in legume-grass systems on low P soils the primary nutritional limitations are phosphorus in the west season and nitrogen, and perhaps energy, in the dry season. This work is supported by the Australian Meat Development Corporation. MILLER, C.P. and WEBB; C.D. (1988). and Livestock Research and Proc. Aust. Soc. Anim. Prod. 17:441. * Queensland Department of Primary Industries, Hareeba, Qld. 4880. 526