Coping with rainfall variability in tropical savannas
O'Reagain, P.J. Dr; Ph: (07) 4787 2155; Fax: (07) 4787 4998; oreagainp@dpi.qld.gov.au
Research organisation: Queensland Department of Primary Industries, Queensland Beef Industry Institute, PO Box 183, Charters Towers Qld 4820
Objectives:
1. Compare and demonstrate the ability of different grazing management strategies to cope with rainfall variability in terms of their effects on pasture condition, animal production, economic performance, soil loss and biodiversity;
2. Develop, in conjunction with graziers, practical and sustainable grazing management strategies to assist producers in coping with rainfall variability;
3. Promote the adoption of these strategies through demonstration and direct links to the property management planning and PDS projects and local landcare and catchment management groups.
Methodology: Five 100 ha paddocks will be erected on a site situated on a land type typical of the Dalrymple shire. In consultation with producers five different stocking strategies will be selected and one run in each paddock. Potential strategies could include light stocking (utilise 30 per cent of available herbage in most (> 70 per cent) years), heavy stocking (70 per cent utilisation in most years), variable stocking (stock numbers adjusted annually at the end of the wet according to available herbage), variable (adjustment made in October based on SOI predictions) and rotational spelling (a quarter or a third of the area spelled each season to act as a drought reserve or to carry a fire, depending upon rainfall). To avoid the problem of between paddock differences, all treatments would be repeated twice giving ten paddocks in total. Paddocks would be stocked with approximately 15 steers of 18 months age. Restocking would occur annually in April but some animals could be kept to maturity to assess long term growth rates, carcass quality etc. Animals would be supplemented where necessary. Animals would be weighed every three to four weeks depending upon rainfall and growth rates. Pasture species composition, basal cover and tree density would be assessed annually in each paddock along fixed transects. Soil and nutrient loss would be assessed from mini catchments (10-50 ha) established in five different paddocks. Catchments would be fitted with flumes and automatic samplers to measure water quality. Biodiversity of invertebrates (ants, beetles etc) and vertebrates (birds, reptiles and mammals) would be assessed in the wet and dry seasons using pit traps, net sweeps, spot light searches etc. Management decisions for the site eg burning, drought feeding, destocking , would be made by a management committee consisting of graziers supported by technical staff and representatives of other bodies. All Queensland Department of Primary Industries extension projects in northern Queensland focused on sustainable grazing will be directly linked to this project site plan.
Progress: Paddock fences erected and project now underway.
Period: starting date 1996-10; completion date 2007-06
Status: ongoing
Keywords: biodiversity; climate; grazing management; native pastures; pasture ecology; pasture monitoring; stocking rate;
Publications: None as yet
