Seasonal changes in dry matter distribution and herbage quality of Urochloa species in north-eastern Queensland

Abstract

Seasonal changes in the dry matter distribution between green leaf, dry leaf, stem and infloresence, and the nitrogen and phosphorus concentrations and in vitro digestibility of these components, were measured in accessions of Urochloa mosambicensis and U. oligotricha growing at Lansdown, near Townsville, between 1979 and 1982. The grasses were grown in mixed stands with Stylosanthes cultivars and fertilised annually with superphosphate. U. oligotricha accessions were more leafy than U. mosambicensis accessions. In all accessions, the proportion of green leaf was high at the start of the growing season and then declined, usually to zero by the end of the dry season. The proportion of green leaf was closely related to water supply as indicated by a moisture index. The differences between accessions for chemical composition and digestibility were much smaller than the differences between sampling dates, and accessions did not differ markedly for herbage quality.