Rate of Decomposition and Release of Nutrients from Litter in a Heteropogon contortus-Bothriochloa bladhii Dominant Native Pasture

Litter dry matter (DM) decomposition and nutrient (N, P, K and S) release were measured for 8, 6-monthly periods in south-eastern Queensland. Litter collected from native paslure growing on a range of soil types was hammer milled, and buried in nylon bags at the collection site, Moisture and (tn a lesser extent) temperature had a greater effect on DM disappearance from nalive pasture litter than its chemical composition or the soil type. A simple index of litter disappearance was derived from average air temperature and surface (0-10 cm) soil water. Based on long-term rainfall and temperature data, 24.8% of litter decomposes over the summer 3 months, as against 16.4% over the winter 3 months. Nutrient release was small and variable and not related to any factors that we measured. N and S were lost slowly with time in a linear fashion, leading to an increase in their concentration respectively to 0.75% and 0.045%. P and K were lost rapidly in the first month, then slowly thereafter, so that initial and final concentrations were similar (final concentration being 0.05S% and 0.12% respectively).