Information
Level 2 Detail of Experimental Conditions and Methods
When and Where?
The study commenced in December 1997 and concluded in 2000. Two treatments were carried out on the Palmas site which was located 20 km north-west of Ingham, Queensland, Australia. The site is located within the wet tropical region of Australia. The Palmas site is located on a commercial sugarcane farm within the Ripple Creek catchment, which is a sub catchment of the Lower Herbert River.
The Palmas property was located on a commercial sugarcane farm in a field 2 km along Palmas Road, off Hawkins Creek Road and is 500 m long and 200 m wide. A second site on the Palmas property was selected approximately 500 m north-west of the main Palmas site and is also 500 m long and 200m wide.
The third site was separate from the Palmas property and was located at Macknade Mill (CSR Sugar Ltd) approximately 10 km east of the Palmas property. The field was divided into four experimental plots 35 m wide and 20 m long.
Soil Type
The soil at the Palmas site was a dark grey clay texture A1 horizon, with a cracking surface, neutral pH trend and a weakly developed A2 horizon. The B horizon is strongly mottled grey light clay that grades to a mottled yellow brown heavy clay C horizon and a yellow brown sandy D horizon below 1.4 m. The soil has been classified as a Kurosolie Redoxic Hydrosol and as a Hamliegh / Toobanna soil type.
Palmas secondary site was described as having similar soil to the Palmas Main site, which contained a dark grey, silty clay textured with a cracking surface. This soil was located at the top of the field. The lower part of the field contained dark grey, silty clay with a sharp horizon change at 0.4 m to a heavy yellow brown clay. The soil from the sample in the top and lower part of the experimental area was classified as a Kurosolic Redoxic Hydrosol.
Landscape Features
The Lower Herbert Valley and its associated floodplains are flanked by mountains with elevation in excess of 1000 m, but commonly 600-900 m with steep slopes. The Ripple Creek catchment is typical of the sub catchments of the Lower Herbert Valley, the steep slopes of the upper Ripple Creek catchment remains under native vegetation and the lower flood plains have been cleared for agricultural production. Ripple Creek is the main native drainage line in the catchment although artificial drainage lines have been constructed to assist drainage for agricultural purposes.
The flood plains are dominated by low slopes ranging up to 2%, with there old levee banks and alluvial ridges.
The slope of the field is described in terms of the down slope and cross slope components, where the down slope is the slope along the length of the field and the cross slope is the slope across the width of the field.
Climate
The mean maximum temperature for the study site is 32oC during the summer and drops to 25oC in the winter. Mean monthly minimum temperature range from 23oC during the summer months to 13oC in the winter months, with July having the coolest average minimum.
The mean annual rainfall for Ingham (closest town and weather station) is 2069 mm and exhibits a summer dominated rainfall pattern with approximately 80% of the median rainfall occurring between December and March. The large rainfall events are driven by the incidence of rare cyclonic events in the wet season (summer).
How?
Field Treatments
A soil pit was dug at the Palma's site to a depth of 0.75 m and 2.0 m. Soil samples were removed for moisture retention and hydraulic conductivity determinations. Single ring infilrometers were used to measure the infiltration rate of key soil horizons which in turn used to establish the saturated hydraulic conductivity of the 4 soil horizons observed in the pit.
A series of experiments were conducted at the Palma's site to establish a depth discharge relationship, the resistance to flow of runoff and to measure in situ soil hydraulics properties. Flumes were installed to measure the runoff from the field and shallow wells were installed to observe and measure the fluctuating shallow watertable. Time domain reflectometer probes (TDR) were installed to measure the volumetric soil moisture content at several depths and redox probes were installed to measure the reduction potential of the soil at two depths in the field.
Soil samples were collected from the study site and analysed in the laboratory for soil water retention and hydraulic conductivity curve.
Modelling
A processes model, Storm Water Management Model (SWMM), a Unit Hydrograph and a watertable drawdown model were used to model the hydrology of the sugarcane field at the Palma's site. In addition two sugarcane yield-watertable response models (RC and GOYLE) were coupled to the watertable drawdown model.
Inundation
Run-on Experiment
The run-on experiments were conducted to determine if the depth discharge equation and the Manning's equation were valid for the types of flow present within low lying sugarcane fields. The experiment was conducted over a series of weeks at the Palmas site, which had been harvested approximately 4 weeks previously and had a 30-50 mm thick trash blanket.
The run on experiment consisted of sections of:
- Row with low slope;
- Row with steep slope;
- Cross rows at 90o; and
- Cross row at 45o.
All slope treatments were replicated with and without trash present.
The low slope and steep slope water were supplied to the buffel box to still the water and then allowed to overflow into an eight inch cutthroat flume. Measurements of inflow and outflow were taken.
For the cross row run experiment artificial channels were constructed at 90o and 45o to the furrow by using a sheet of fibre that was dug in to the ground at a depth of 2000 mm. Inflow and outflow flumes were installed at each of the fibre cement channels. Measurements of the outflow and inflow water taken at the site.
Waterlogging
The measurement of soil hydraulic properties involved both field and laboratory analyses. Undisturbed soil cores were sampled from the interrows and rows from the site and were subject to standard soil hydraulic measurements. Some of the hydraulic measures included:
- Soil moisture retention;
- Hydraulic conductivity; and
- Specific yield.
Modelling Plant and Water Processes
The aim of the modelling in the present study is to accurately simulate the physical processes under varying climate influences over periods of time. Surface water modelling was conducted using:
- SWMM (Storm Water Management Model);
- APSIM (Agricultural Production Simulation Model);
- Crop Yield Model;
- Goyle model; and
- Rudd and Chardon Model.
Project administration
Site identifier code: N/A
Principal investigator: Mitchell DC
Principal data manager: N/A
Principal organizations: James Cook University
Data custodian: James Cook University
Key co-operators: Cooperative Research Centre for Sustainable Sugar Production, CSIRO Land and Water, Tony Palmas
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