Information
Level 2 Detail of experimental conditions (what might be found in a journal paper or project brief in Hydstra)
Description of study
What?
This study involved using a rainfall simulator to investigate soil erodibility and the effects of pasture cover on soil erosion at four selected sites, represented by four soil profile classes: Beer (Sodosol), Neara (Chromosol), Pinch (Chromosol), and Beppo (Vertosol).
When and Where?
The rainfall simulator study was performed in 1995 and 1996. The site is located 3.3 km north of Esk. The slope of the land 6% with low hills. The predominate soil type is grey clay with mostly alkaline horizons. For the complete soil description please view attachment 1.
How?
Measurements of rainfall, infiltration and sediment transport were recorded from a rainfall simulator, run over a 40 minute rainfall period at a rate equivalent to a 100 mm/hr storm (approximately 67 mm in 40 minutes).
Treatments used at varying slopes included:
- ‘Bare’ – sprayed, mown, raked and left bare for some months to create a worst case over-grazed surface with no grass or little cover;
- ‘Reduced cover’ - mown or raked, resulting in short grass but generally having <60 % cover; and
- ‘High cover’ – untreated pasture with almost 100% cover.
Because Beer soil type has high infiltration rates compared to the other three soil types, extra rain was applied (150 mm) and a final infiltration rate similar to the other three soil types was recorded.
Relative erodibility of soils (sediment loss) was assessed by comparing sediment transported at each of the sites. Because slope varied between sites and between individual treatments at each site, soil loss results were corrected for slope (a nominal 9% slope) for bare (0% cover) soil.
Two soil erodibility factors (K factors) were calculated for each soil types using two methods.
The first Kfactor (K1) was calculated from experimental results using the Rose soil loss equation.
The second K factor (K2) was calculated using the revised ‘nomograph’ method of Loch and Rosewll from laboratory analysis and field soil structure assessment. This is a Universal Soil Loss Equation soil erodibility factor, which assumes that the soil is cultivated.
The results from the rainfall simulation and the K1 factor represent soil loss and erodibility due to sheet erosion processes.
The K2 soil erodibility factor was used to provide insight into the likely erosion of soils under both sheet and rill erosion.
For comparison, soil erodibility factors were calculated for two other soils in southeast Queensland (cultivated Vertosol at Greenmount and cultivated Vertosol at Greenwood).
Project administration
Site identifier code: na
Principal investigator: Harms BP
Principal data manager: -na
Principal organizations: Department of Natural Resources Queensland, Brisbane.
Data custodian: Department of Natural Resources, Toowoomba
Key co-operators: Agricultural Production Systems Research Unit, Department of Natural Resources, Toowoomba
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 -na
Planned data upload frequency: for ongoing studies -na
Key references and sources of this data synthesis
These data summaries have been extracted from
- Harms BP and Silburn DM. 1999. Section 5.2. Soil erodibility and runoff for Brisbane Valley soils. In. Land Resources Assessment of the Brisbane Valley, Queensland (BP Harms SM Pointon). Land Resources Bulletin DNRQ990065, Department of Natural Resources Queensland, Brisbane.
Keywords:
Rainfall simulator, infiltration, sediment transport, runoff, Beer