Impact of phosphorus fertiliser on tropical pasture legume production

Abstract

The application of phosphorus (P) fertilisers during legume establishment can substantially increase yields, however the P requirements of many tropical legumes has not been defined. A trial was established on low P soils near Wandoan in southern Queensland to investigate the effect of P fertiliser on tropical legume production during establishment and the three years post sowing, with early results reported in this paper. The trial consisted of single cultivars of three tropical legume species (Desmanthus leptophyllus, Desmanthus virgatus and Stylosanthes seabrana) with five rates of P fertiliser applied. No significant difference between the three species was identified, suggesting the three legumes responded to P fertiliser similarly. Across the three species a 20% increase in yield was achieved with P application. The critical soil P level, defined as 95% of maximum yield, ranged between 12 and 14 mg/kg. The addition of P fertiliser on low P soil during tropical legume establishment results in greater legume productivity which is expected to increase livestock production.