Level 2: Detail of experimental Conditions


This study monitored the loss of nitrogen from runoff of irrigated and rain-fed 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.

One site was located on the Delta of the Burdekin River, where groundwater is the dominant irrigation water source. Delta soils contain silty textured surface horizons, but sub soil texture varies from light clay to course sands across the district. Soil at the Delta site was non saline, but sodic especially at depth. The site was 2.5 ha in size with rows of sugarcane 1.52 m apart and 500 m long. The average slope of the site was 0.13%. The first crop grown was planted on the 14 April 2004.


To determine N concentrations in the harvested crop immediately prior to burn and mechanical harvest sugarcane stalks were harvested from small areas within each plot. This sampling involved hand cutting stalks at ground level over a 5 m 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 from samples obtained at the commencement of the experiment, prior to application of fertiliser nitrogen.

Soil samples were taken in increments of:

  • 0-0.15 m;
  • 0.15-0.30 m;
  • 0.30-0.60 m;
  • 0.60-1.0 m;
  • 1.0-1.5 m; and
  • 1.5-2.0 m.

This was conducted using a 50 mm diameter steel tube from four randomly chosen locations at each site.

Rainfall was measured at each site using an automatic tipping bucket rain gauge. Irrigation was measured with a flow meter connected to the irrigation pump.

Runoff was measured automatically at the Delta site 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. This resulted in some flows not being recorded.


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 and 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. 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 – Mona Park site

Environmental impacts of irrigated sugarcane production: Nitrogen lost through runoff and leaching – Mulgrave 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



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