Information
Level 2 Detail of experimental conditions (what might be found in a journal paper or project brief in Hydstra)
Description of study
What?
Runoff and soil loss were measured in a 1ha bounded catchment using San-Dimas Flumes in relation to a number of stocking variables including:
- Constant Light Stocking Rate (LSR);
- Constant Heavy Stocking Rate (HSR);
- Variable Stocking Rate (VAR);
- Southern Oscillation Variable (SOI); and
- Rotation Wet Season Spelling (R/Spell).
When and Where?
The trial was located in Wambiana, 70 km South West of Charters Towers. Rainfall here is highly seasons, with most (70%) falling between December – March. A long dry season occurs in interval months. The study area is located in the Arittida-Bothrichloa pasture community and is an open savannah.
Soils are derived from tertiary sediments and are relatively infertile. Paddosck were laid out to ensure that experimental paddocks contained similar percentages of the 3 main soil-vegetation associations. The experimental area included:
- Euclayptus melanipholia and unpalatable grasses such as Aristida spp. on yellow-red kandosols (23% of the area) (Low fertile area and poor drainage);
- Acacia harpophylla – Euclyptus brownii community on grey vertosol (22% of the area). This area is largely dominated by Dicanthium sericeum, Bothrichloa ewartiana and Eulalia aurea (more fertile area); and
- E.brownii community on brown sodosols and chromosols (55% of the area). Dominated by fallax – Bothrichloa ewartiana pasture (moderate fertility, shallow soil 30-40cm).
How?
Rainfall
Rainfall data (quantity and intensity) was collected via a tipping bucket pluviometer, recording at one-minute intervals.
Runoff and Soil loss
Runoff was collected at the bottom of catchments by wing-walls, which funnel runoff towards a sediment trap and San-Dimas flume (Figure 1). Macquarie borehole loggers measured flow height and duration at one-minute intervals. This allowed for the interpretation of runoff rates and volumes
Water Quality
Samples were collected from each treatment using auto samplers which were programmed to collected water at the first flush and at 10mm change in flow height thereafter. Additionally, reference samples were collected from a number of creeks and rivers during moderate to major flooding events. Sampled locations included:
- Policeman Creek;
- Oaky Creek;
- Campase River; and
- Burdekin River at Macrossan.
Samples were analysed for a number of parameters including:
- Total Suspended Solids (TSS);
- Total Nitrogen (TN);
- Total Filterable Nitrogen (TFN);
- Nitrate;
- Nitrite;
- Total Phosphorus (TP);
- Total Filterable Phosphorus (TFP); and
- Ammonia.
Animal measurements
Animal production was measured using Brahman-cross steers, supplemented with wet-season phosphorous and dry season urea. Accumulated cash surplus (ACS) was calculated from annual gross margins (GM) i.e. the value of beef produced minus variable and interest (10%) costs. Pasture total standing dry matter (TSDM) and species contribution to yield were assessed annually in May. Species data is grouped into 5 functional groups i.e. 3-P and 2-P (palatable, productive and/or perennial) grasses, wiregrasses (Aristida and Eriachne spp.), annual grasses and ‘other’. 3-P tussock densities were derived from tussock counts in 0.25 m2 quadrats measured in May 2007. Pasture utilisation rates were calculated retrospectively using the GRASP model (McKeon et al., 1990) calibrated for the site.
Project administration
Site identifier code: na
Principal investigator: Peter O’Reagain
Principal data manager: -na
Principal organizations: NQ Dry Tropics land and water solutions, Australian Centre for Tropical Freshwater Research
Data custodian: Department of Environment and Resource Management (DERM)
Key co-operators:
Data access policy:
Planned pathway for data: completed study, publish in Marine Pollution Bulletin
Data warehousing: for ongoing studies -na
Planned data upload frequency: for ongoing studies -na
Key references and sources of this data synthesis
These data summaries have been extracted from:
- O’Reagain P, Bainbridge Z, Brodie J (2008). Wambiana Grazing Trail: Water Quality Update to Burdekin Dry Tropics NRM Region. NQ Dry Tropics.
- O’Reagain P.J, Brodie J, Fraser G, Bushell J.J, Holloway C.H, Faithful J>W, Haynes D (2005). Nutrient loss and water quality under extensive grazing in the upper Burdekin river catchment, North Queensland. Marine Pollution Bulletin 51: 37-50.