SA Mid North Lower Eyre Peninsula Regional Summary
The region
The SA Mid North Lower Eyre Peninsula agroecological zone is split by the Spencer Gulf. A small section of the Eyre peninsula from south of Ungarra is in the zone and the remainder of the zone is on the eastern side of the Spencer Gulf. The northern boundary of this part of the zone is just to the south of Quorn and the zone extends south to Yorketown and includes Kangaroo Island. Rainfall in the zone ranges from > 1000 mm annum-1 in the south to < 400 mm annum-1 in north. Rainfall seasonality is winter dominant. Boundaries for the zone are shown in Figure 1.
Modelling regional practices
Producing models that reflect all farming practices throughout a region is difficult so “common practice” models for wheat, canola and lentils for the region were produced. A wheat crop with a 2.9 t ha-1 yield and 46 kg of fertiliser N applied ha -1, a canola crop with a yield of 1.5 t ha-1 with 53 kg fertiliser N ha -1 applied and a lentils crop with a yield of 2.1 t ha-1 and 7 kg of fertiliser N ha -1 applied were modelled. The key assumptions of these models were that;
- Only one pass was made at sowing
- Split fertiliser applications were used for wheat and canola crops
- It was assumed that wheat and canola had two fallow herbicide applications, one in-crop herbicide application and one fungicide application. Canola also had one insecticide application. Lentil crops had two fallow, one pre-emergent and two in-crop herbicide applications and one fungicide application.
- Stubble was retained
Impact indicators
Hydrogen ion impacts estimate the release of hydrogen ions to the soil associated with crop production. A negative value indicates a reduction in soil acidity whereas a positive value indicates an increase in soil acidity. Soil erosion is an estimate of soil loss that occurs during the production of the crop. The depth of soil lost will depend on many things but an approximate conversion is that 1.5 t of soil loss equals 1 mm of soil. Global warming impacts are the release of greenhouse gases to the atmosphere expressed as carbon dioxide equivalents (CO2-e), Eutrophication impacts are the release of phosphorous to the environment and are expressed as phosphate equivalents and Particulate Matter impacts are the release of fine particles less than 2.3 micrometres in diameter.
Benchmark results
Results below in Table 1 show the environmental impacts of producing a t of wheat, canola or lentils in the region. An absence of lime use in the region resulted in an increase in free hydrogen ions in the soil for all crops and soil erosion was estimated at between 2.9 and 5.6 t soil loss t product-1. Analysis indicated that Global warming impacts associated with the production of these crops ranged from between 85 and 597 kg CO2-e, Eutrophication impacts ranged between 1.2 and 5.2 kg PO4-e and Particulate Matter impacts ranged between 0.13 and 0.6 kg of < 2.3 µm particulate matter t product-1.
Table 1: Hydrogen ion changes, soil erosion and Global Warming, Eutrophication and Particulate matter impacts associated with the production of wheat, canola and lentils in the SA Mid North Lower Eyre Peninsula agroecological zone.
Hydrogen ions | Soil erosion | Global warming | Eutrophication | Particulate matter | |
|---|---|---|---|---|---|
(kg H+) | (t soil loss) | (kg CO2-e) | (kg PO4-e) | (kg PM2.3) | |
Wheat | 3.00 | 2.91 | 280.00 | 2.48 | 0.30 |
Canola | 4.99 | 5.55 | 596.96 | 5.2 | 0.60 |
Lentils | 1.38 | 3.92 | 85.36 | 1.2 | 0.13 |
Greenhouse gas emissions
The emissions profile of all three crops are shown below in figure 2. For wheat and canola, the greatest source of emissions was the use of fertiliser. The production of fertilisers and residue breakdown were also made a relatively high contribution to total emissions where as other emissions sources were relativel low. Emissions from residue dominated the emissions profile of lentil production mainly because lentil production used realtively small amounts of fertiliser.
Figure 2: Greenhouse gas emissions profile for the production of wheat, canola and lentils in the SA Mid North Lower Eyre Peninsula agroecological zone.Greenhouse gas mitigation strategies
Mitigation strategies tested for the region were;
- Sustainable intensification
- Implementation of variable rate fertiliser technology
- Changing a wheat-wheat rotation to a legume-wheat rotation
More information on the assumptions used to test these strategies and how they might reflect individual enterprises are available on the Mitigation strategies page.
Results (figure 3 below) indicate that emissions of a t of wheat can be reduced by;
- 42% through the implementation of sustainable intensification
- 16% by implementation of variable rate fertiliser technology
Results also indicate the replacing a wheat crop with a legume crop in a two-crop rotation can increase greenhouse gas emissions intensity by 125%.
Figure 3: Reductions in greenhouse gas emissions for wheat production when grown with sustainable intensification, variable fertiliser and legume - wheat mitigation strategies in the SA Mid North Lower Eyre Peninsula agroecological zone.
Accessible content
Visit accessible versions of the raw data used to generate these charts.
More information
Dr Aaron Simmons
Orange Agricultural Institute
1447 Forest Road
Orange NSW 2800
P: 02 63913894
E: aaron.simmons@dpi.nsw.gov.au
