RESPONSE OF STYLOSANTHES-HAMATA CV VERANO AND NATIVE PASTURES TO FERTILIZERS ON 2 LIGHT-TEXTURED SOILS IN NORTH-WEST QUEENSLAND

The effects on yield and quality of applying fertilisers to Stylosanthes hamata cv. Verano (Caribbean stylo) and to native pastures were measured in 3 field experiments on a grey kandosol and a brown sodosol supporting Melaleuca woodlands in north-west Queensland. Phosphorus application at a rate of 30 kg/ha P increased Verano yield annually in the first 4 years. The maximum yield achieved was > 6000 kg/ha on a grey kandosol in the second year. Eighty percent of maximum legume yield was achieved with acid-extractable soil P levels of 8 mg/kg. There was also a yield response to sulfur and zinc at establishment, but not in subsequent years. The nutrient concentration responses of Verano to fertilisers are reported. Dry matter yield of native pasture was increased by both nitrogen (from 2050-3630 kg/ha) and superphosphate (to 3080 kg/ha) fertiliser in the first year, but not in the second growing season when rainfall was low. Concentrations of P and S in the native pasture were increased by super-phosphate (from 0.03% and 0.07% to 0.12% and 0.10% respectively) in the first season. Productive Verano pastures with nutrient concentrations adequate for animal production can be grown on these infertile soils by applying single superphosphate alone. Most commercial pastures are not adequately fertilised and an application of 30 kg/ha P every 5 years is suggested.