Information
Level 2 Detail of experimental conditions (what might be found in a journal paper or project brief in Hydstra)
Description of study
What?
Changes in the soil structure and hydraulic properties of the root-zone following the implementation of raised beds on waterlogging-prone duplex soils in W.A were monitored.
When and Where?
5 trials were established in 1997 across the south-west of WA, at Beverley, Woodanilling, Mt Barker Research Station (MBRS), Cranbrook, and Esperance Downs Research Station (EDRS). The sites ranged from 11 – 17ha and were located on a range of duplex soils.
In 1998 another site was added, Lake Toolibin and in 1999 another 2 sites, at Badgebup and South Stirling. These 3 sites were used as demonstration sites and were much larger (50 – 66ha). The soil types at these sites ranged from sand and gravel over clay to a sandy clay loam over grey clay with variable depths to clay, ranging from 0.05 to 0.40 m. Further site details can be found in Table 1.
How?
Two replicated treatments were installed at all sites: raised beds and a ‘district-practice’ as a control. At all sites the control did not receive any cultivation before seeding. At the sites where dispersible subsoil was present, gypsum was applied across the treatments. The raised bed treatment received an initial deep cultivation using a multi-tyne deep ripper followed by a cultivation with a scarifier and then the formation of the beds. Similar rates of fertiliser were applied to the beds and the control. Weed and pest control were carried out as required.
The raised beds were installed using a Gessner bed former. The furrows were spaced at 1.83m apart, about 0.25m deep and 0.45m wide across the top. The furrows were formed with hillier units, which were ripper tynes with a curved blade on both sides of the tyne. Three full sized and two half sized beds were made in 1 pass.
In the first year Beverley, Woodanilling and Cranbrook were sown to oats. MBRS and EDRS were sown to wheat. The new site in 1998, Lake Toolibin was sown to oats whilst the sites in 1999, Badgebup and South Stirling were sown to canola and wheat respectively. Before the growing season the raised beds were renovated with blade ploughs mounted on ripper tynes.
Bulk density measures were taken only at Beverley, Woodanilling, Cranbrook, MBRS and EDRS. Measures were taken using with 3 undisturbed soil cores from 2 locations in each treatment at 3 depth intervals at least once a year. Infiltration properties were determined at only Beverley, Woodanilling and Cranbrook. Infiltration properties were determined using disc permeameters modified to house a water level sensor and datalogger. The measurements were carried out in the autumn of 1998 and in August 1999, 2000, and 2001. At least 4 measurements were done at a negative potential and at least 8 at the positive potential.
Perched water table observation wells were installed to a depth of 0.45m at Beverley, Woodanilling and Cranbrook and were monitored. Soil moisture changes to a depth of 0.45m over time were collected at the Cranbrook site using a time domain reflectometer. The probes, aluminium blocks with stainless steel rods, were inserted at a soil depth of 0.10, 0.25 and 0.45m in a raised bed plot and the adjacent control plot. The moisture content was obtained every 30min and adjusted for the gravel content at the various depths.
Summer stubble grazing was implemented in Cranbrook by fencing the appropriate control and raised beds plots over the summer period. A flock of 70 sheep was confined to one plot at a time for 7 days. The plot size was 0.5ha and the grazing pressure equated therefore to 940 grazing days/ha.
Runoff in Cranbrook was measured using sharp crested ‘V’ notch weirs in combination with capacitance probe water level recorders. The plots discharged in a drain and the flow in the drain was measured at the boundary of each plot. The runoff of the individual plots was then calculated by subtracting the inflow of a plot section from the outflow.
Project administration
Site identifier code: N/A
Principal investigator: Bakker DM, Hamilton GJ, Houlbrooke DJ and Spann C
Principal data manager: N/A
Principal organizations: Western Australian Department of Agriculture
Data custodian: Western Australian Department of Agriculture
Key co-operators:
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
Key references and sources of this data synthesis
These data summaries have been extracted from:
- Bakker DM, Hamilton GJ, Houlbrooke DJ and Spann C. (2005). The effect of raised beds on soil structure, waterlogging, and productivity on duplex soils in Western Australia. Australian Journal of Soil Research 43: 575 – 585.
Keywords:
Mediterranean climate, raised beds, cropping, runoff