State of Queensland, Department of Employment, Economic Development and Innovation
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.