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The Wambiana trial was established in December 1997 near Charters Towers to objectively test
how a range of grazing strategies cope with climate variability. To ensure relevance to the grazing
industry, the trial was run in close association with a grazier advisory committee. Trial paddocks
contained a range of soil types to reflect conditions in large, commercial paddocks.
The different grazing strategies tested were:
1. Heavy stocking (HSR) stocked at twice the long-term carrying capacity (LTCC) of the site.
2. Moderate stocking (MSR) stocked at the LTCC.
3. Variable stocking (VAR) with stocking rates adjusted annually in May based on forage
availability.
4. Southern Oscillation Index (SOI)—variable strategy with stocking rates adjusted annually in
November according to forage availability and the SOI.
5. Rotational wet season spelling (R/Spell) coupled with moderate-heavy stocking.
Strategies were compared in terms of their effects on animal production, economic performance
and land condition. Collaborative work with other agencies was also done to compare how these
strategies affected biodiversity, soil health, soil carbon and grazing behaviour.
Rainfall varied sharply over the trial period from some of the wettest to some of the driest years
on record. While several of the observed trends in animal production and pasture composition at
the trial are expected, a number of unexpected results and novel interactions have been recorded
as the long-term effects of the different treatments have emerged.
A summary of the key findings and principles from the trial covering the 13 years to date are
presented overleaf. Further detail is provided in subsequent sections. The publication concludes
with some key learnings and management guidelines for grazing in a variable climate.