Landscape - carbon, nutrients, water and productivity - Ashburton River
Ashburton River
Why are material budgets useful?
The availability of light, water and nutrients determines the capacity of land to produce natural vegetation and agricultural yield. In Australia, long-term availability of resources and the consequent potential for generating yield, can be assessed by examining the mass balances of the key resources: water and nutrients (in this case nitrogen and phosphorus). Mass balance gives a quantitative picture of:
- resource inflows or sources;
- resource outflows (including both production outputs and unproductive losses or leakages);
- the resource stock (the amount available for use); and
- the way that the stock changes with time in response to the various inflows and outflows.
The mass balances of water and nutrients are linked by carbon (or biomass) since plant biomass is approximately 50% carbon. Balances and cycles of water, nitrogen, phosphorus and carbon interact and constrain each other.
The figure below provides a schematic of how the couple balances carbon, nutrients and water were constructed and linked to sediment and nutrient transport.
Landscape carbon, nutrients, water and productivity budgets
The table below presents the key material budget terms modelled or collated as part of the Australian Agriculture Assessment 2001 projects.
The budget terms cover:
- Coupled balances of carbon, water, nitrogen and phosphorus
Detailed separately are:
Key river basin characteristics such as broad agricultural land use categories and climate are provided for context. All attributes are presented as aggregate mass, rate, ratio or percentage estimate at a river basin scale
Context for understanding the material budgets for Ashburton River
| Attribute | Unit | Basin value | Median Australia-wide value |
|---|---|---|---|
| Basin area | km2 | 75,716 | 7,208 |
| Improved pasture | % | 0 | 1 |
| Cropping | % | 0 | 0 |
| Horticulture | % | 0 | 1 |
| Total agricultural land proportion | % | 0 | 7 |
| Climate | |||
| Rain | mm/y | 308 | 860 |
| Total evaporation | mm/y | 301 | 584 |
| Runoff | mm/y | 7 | 249 |
Carbon, nutrients, water and productivity in Ashburton River
| Attribute | Unit | Basin value | Median Australia-wide value |
|---|---|---|---|
| Net Primary Production | tC/ha/y | 0 | 3 |
| Plant carbon | t/ha | 6 | 76 |
| Litter + soil carbon | t/ha | 12 | 78 |
| Landscape nutrients | |||
| Nitrogen from fertiliser | kgN/ha/y | 0 | 0 |
| Nitrogen fixation | kgN/ha/y | 1 | 17 |
| Total nitrogen | kgN/ha | 909 | 6,742 |
| Mineral nitrogen | kgN/ha | 18 | 85 |
| Mineral nitrogen concentration in soil water | mgN/kgwater | 31 | 50 |
| Nitrogen leached | kgN/ha/y | 2 | 9 |
| Nitrogen volatilised | kgN/ha/y | 0 | 2 |
| Phosphorus from fertiliser | kgP/ha/y | 0 | 0 |
| Total phosphorus | kgP/ha | 155 | 1,062 |
| Dissolved mineral phosphorus | kgP/ha | 3 | 14 |
| Phosphorus concentration | mgP/kgwater | 6 | 9 |
| Phosphorus leached | kgP/m2/y | 0 | 1 |
Further information
- Australian Agriculture Assessment 2001 report
- Landscape balances chapter of the Australian Agriculture Assessment 2001 (theme) report
- Report prepared by CSIRO Land and Water in the development of this work on the coupled balances of water, nutrients and carbon in Australian landscapes (PDF - 3.5 MB)
- Report prepared by CSIRO Land and Water in the development of this work on the coupled balances of water, nutrients and carbon in Australian landscapes (PDF - 1300 KB)
- Link to the Map Maker to make a map using this information.
- Data Library
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