Information
Level 2: Details of Experimental Conditions and Methods
When and Where?
The study was carried out in the Burdekin River Catchment, a major catchment of the Great Barrier Reef (approx 130,000 km2) west of Townsville. The rainfall simulation was conducted in July 1998.
The general description of the site:
- Stylo monitoring site with native pasture;
- Moderately to heavily grazed and a Stylo dominant pasture;
- Ground cover very patchy; and
- General site condition moderate to poor.
Soil Type
The soils from the site are varied but generally old and weathered with a large proportion of duplex soils. With the exception of soil derived from basalt (Vertosols or Ferrosols) most of the soils are low in fertility and due to their textual properties, are particularly prone to crust and hard setting. The six sites are located on duplex or gradational soil types that are common within the Upper Burdekin River Catchment.
Soil Description for Thangala (Site 1):
- Yellow Kandosol (Boston Series);
- Sand- nd;
- Clay- nd;
- Bulk Density- 1.53-1.90 g/cm3;
- Moisture- 0.006-0.15% volume;
- Ground Cover- 8-98%; and
- Biological Activity- 1-2
Landscape Features
Feature of Site 1 include:
- Silver leaf Ironbark as the dominate vegetation trees;
- Wiregrass and Stylo as the dominate grass or legume species;
- Upper hillslope of 0-3%; and
- Geology- Cainozic sediments.
How?
Six sites were selected on duplex and gradational soil types typical of large parts of the catchment. Individual plots reflecting the main classes identified were selected with two to four replicates per class, resulting in about ten to sixteen plots per site.
The rain simulator consisted of 1m2 capillary tube (inner diameter 0.5mm) drop forming chamber mounted on a 4m high aluminium tower. The tower was attached to a trailer that supported the equipment to conduct the rainfall simulation.
The rainfall intensity varied between 30 and 75mm h-1. The targeted intensity for this study was 60mm h-1 for 30 mins, which represents a storm event having a 1 year return period for northern Queensland.
Metal runoff plot frames 0.4 m by 0.6 m in size were placed in the middle of the rainfall plot, thus allowing a 0.2m - 0.3 m buffer zone around the plots. An angle grinder was used to cut slots into dry ground to enable insertion of the frame into the soil without disturbing surface features.
The following soil features were recorded from the experiment:
- Estimate of ground cover (green material and litter);
- An assessment of microreleif and plot slope; and
- Range of macroscopically visible crust.
In addition the following criteria were recorded as proposed by (Tongway and Hindley, 1995), this includes:
- Presence and type of crust;
- Extent of cryptogams;
- Extent and nature of surface lag and gravel cover;
- Presence of pedestals;
- Degree of litter incorporation;
- Presence of macropores; and
- Extent of surface casting.
Soil cores were taken from within each plot after the event for bulk density measurements at a depth of 1 cm - 5 cm. Soil moisture was measured to a depth of 1 cm - 5 cm for each plot.
Site identifier code: N/A
Principal investigator: Roth CH
Principal data manager: N/A
Principal organizations: CSIRO
Data custodian: CSIRO
Key co-operators: N/A
Data access policy: Research has been published but base data is not archived
Planned pathway for data: completed study, no evidence of formal database records.
Data warehousing: for ongoing studies N/A
Planned data upload frequency: for ongoing studies N/A