Information
Level 2: Detail of experimental Conditions
What?
This study monitored the loss of nitrogen from runoff of irrigated and rainfed sugar cane farms in North Queensland.
When and Where?
Measurements were made at sites in three districts of the lower Burdekin region. The sites are located on commercial sugarcane farms, with all crops furrow irrigated.
Mulgrave district is within the Burdekin-Haughton Water Supply Scheme which is a recently developed surface irrigation area with water supplied from the Burdekin Falls Dam. The soil texture at Mona Park was medium clay throughout the profile, sub-soils were sodic and the slopes were 0.2%. The Mulgrave district comprised of an area of 11.6ha in area with sugarcane rows 1.53m apart and 1200m long and had open ended irrigation furrows.
How?
To determine N concentrations in the harvested crop immediately prior to burn and mechanical harvest sugarcane stalks were hand harvested from small areas within each plot. This sampling involved hand cutting stalks at ground level over a 5m length within each of the centre two rows. The total mass of these stalks was recorded. A subsample of 15 was randomly chosen to be partitioned into:
- Millable stalk (cane);
- Non millable stalk and green leaf sheaths;
- Green leaf blades; and
- Dead leaves and leaf sheaths known as trash.
Soil mineral nitrogen, total nitrogen and total organic carbon were determined on samples obtained from all sites at the commencement of the experiment, prior to application of fertiliser nitrogen.
Soil samples were taken in increments of:
- 0-0.15;
- 0.15-0.30;
- 0.30-0.60;
- 0.60-1.0;
- 1.0-1.5; and
- 1.5-2.0.
This was conducted using 50mm diameter steel tubes from four randomly chosen locations in each site. The volumes of soil from each sample and its oven dry weight were also determined.
Rainfall was measured at each site using an automatic tipping bucket rain gauge. Irrigation water applied to the field was measured with a flow meter connected to irrigation pump.
Runoff was measured automatically at the Mulgrave district by recording the depth of flow through a Parshall flume with an electronic data logger. (Note the equipment was moved during harvesting and then reinstalled meaning there was some flow missed during the harvest period).
Modelling
Modelling was conducted using APSIM (v.5.3) cropping system model to simulate whole crop water and nitrogen balance at the site. The model configuration consisted of modules for soil nitrogen and carbon, soil water, sugarcane growth and sugarcane residue dynamics.
Movement of dissolved and suspended chemical from the soil in runoff was modelled using the APSIM Erosion module. All models are one dimensional used a daily time step and are driven by climatic data. Parameter values came from three sources:
- Either standard values within the model or some variation of those developed in previous studies;
- Measured or derived values of state variables at the site; or
- In a small number of cases, calibration against measured values.
After the model was parameterised for the site, the growth of the three crops at each site was simulated based on the farmers irrigation and nitrogen fertiliser inputs and the farming operations were recorded at the sites. The model outputs were obtained for crop yield and for various components of the water and nitrogen balance.
Key references and sources of this data synthesis
These data summaries have been extracted from:
Thorburn PJ, Biggs JS, Attard SJ, Kemei J (2001). Environmental impacts of irrigated sugarcane production: Nitrogen lost through runoff and leaching. Agriculture, ecosystems and environment. 144: 1-12.
Related Studies
Environmental impacts of irrigated sugarcane production: Nitrogen lost through runoff and leaching – Delta site
Environmental impacts of irrigated sugarcane production: Nitrogen lost through runoff and leaching – Mona Park site.
Project administration
Site identifier code: N/A
Principal investigator: Thornburn PJ, Biggs JS, Attard SJ, Kemei J
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