Appendix 2 – Net Carbon Emissions
Carbon is exported off the operation either sequestered in the fruit or plant material. This can be accounted for in the Net Carbon Emissions which is calculated by subtracting the carbon locked up in the crop and plant material that is exported out of the system from the carbon imported into the system through energy use.
The carbon content of a crop can be determined by multiplying the dry weight of the organic substances by its carbon content. The typical energy and carbon content of different organic substances is shown in Table A1 (Holland et al, 1991).
Table A1 Energy and Carbon Content of Organic Substances
|
Organic Substance |
Energy Content (MJ/kg) |
Carbon Content |
|
Fats |
37 |
70 |
|
Proteins |
17 |
46 |
|
Carbohydrates |
16 |
40 |
|
Minerals |
2 |
0 |
Table A2 Energy and Organic Substance Content of Tomatoes per 100g
|
Water |
Fats |
Proteins |
Carbohydrates |
Carbon Content |
|
93.76 |
0.33 |
0.85 |
4.64 |
2.48 |
From the typical energy and carbon contents of organic substances given in Table A1 and the composition of tomatoes, Table A2 (USDA and ARS, 2003) it can be estimated that tomato fruit typically contain 24.8 grams of carbon or per kg of fruit, which equals 90.9 grams of carbon dioxide.
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