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 monitored changes in soil water content, runoff and deep seepage between four catchments, two of which were treated by killing trees and planting two pasture species. The intent was to assess land management practices aimed at increasing stocking rate.
When and Where?
From 1972 – 1978 (6 year period) a study was undertaken on four catchments at the Narayen Research Station, 500 km north-west of Brisbane. Narayen is located in a subhumid area, with a mean annual rainfall of 720 mm. The catchments were numbered 1, 2, 3 and 4 and covered areas of 23, 9, 19 and 31 ha respectively. Catchments 1 and 2 were located adjacent to each other, as were catchments 3 and 4.
Approximately 25% of the land surface was covered by tree canopy. Average slopes were approximately 2°.
Duplex soils, formed from weathered granite rock, constitute 95 % of the catchment areas.
Soils range from podzolic (alfisol) to solodic (paleustalf) with 0.25-0.6 m of coarse sandy to gravelly upper horizons abruptly overlaying sandy clay to heavy clay subsoils, which grade into weathered rock below 0.8-0.9 m
How?
Catchments 2 and 3 were treated in February 1975 by removing trees with Tordan 90 and sewing Siratro and green panic seeds.
Soil water content was measured by a neutron meter. Access tubes were installed from the base to the top of the catchments, in clearings between trees, to a 1 m depth, or to the decomposed granite if this was less than 1 m from the surface. Three tubes were installed in each catchment to a depth of 3 m to measure changes below 1 m.
A weighing procedure was used to calculate a single representative soil water content profile at each measurement date. This was calculated by averaging soil water content for the 0-0.2 m layer from those sites with the clay layer at a similar depth, and weighting this average by the fraction of the catchment occupied by soil with clay at that depth. This was repeated for every 0.2 m layer to 1 m to give a single representative soil water profile.
Measuring weirs were installed at catchment outlets (Figure 1) to assess the stage height of discharge from each catchment after prolonged rainfall.
Though low hydraulic conductivity of the overlying clay would limit deep seepage, deep seepage was measured by installing watertight NMM tubes into the granite to a depth of 3 m.
Project administration
Site identifier code: na
Principal investigator: R. E Prebble
Principal data manager: -na
Principal organizations: Division of Soil, CSIRO
Data custodian: CSIRO
Key co-operators: Narayan Research Station
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
- Prebble R.E, Stirk G.B Hydrological effects of land use change on small catchments at the Narayen Research Station, Queensland. Australian Journal of Soil Research. 26: 231-242.