Nutrient requirements of Stylosanthes guianensis pastures on a euchrozem in north Queensland

Abstract

The nutrient status and fertilizer requirements of a euchrozem representing an extensive area of soils derived from basalt were examined in three field experiments in northern Queensland. Stylosanthes guianensis responded strongly to sulphur but not to phosphorus or any other element. With the addition of 20 kg S ha-1, annual pasture yields exceeded 10,000 kg ha-1 with clearing and cultivation and 8000 kg ha-1 without clearing or cultivation. Without added sulphur, annual yields were 4500 kg and 1200 kg ha-1 respectively. It is suggested that similar responses will be widespread on these soils. In established stylo, yields above 90 per cent of maximum coincided with N/S ratios below 17.5. Adequate legume establishment on these soils required either cultivation or up to 10 kg S ha-1. Although maintenance requirements need to be defined under grazing, there is evidence that the residual value of added sulphur is considerable.