Additional File 1: Network Diagrams
Civic Chicken Producer 1: production of 1 kg of chicken meat and CO2 equiv emissions
In this model about 7.7kg CO2 equivalent emissions are produced for one kg of cooked chicken meat on the consumer’s table. The main contributors are the feed- the layer and scratch mixes together account for about 2kg –and car travel by Civic Chicken Producer 1 to collect feed contributes about 4 kg, assuming that only feed is collected during the trip. If other items shared the fuel usage, this contribution would be diminished. (Aim to check this later by re-doing model accordingly). Manure management contributes an offset by reducing the need for synthetic fertiliser production.
Civic Chicken Producer 1 and production of 1 kg of chicken meat: land use (hectare-yrs)
In this model 0.005 hectare-years (50 sq metres over one year) are used to provide for 1kg of chicken meat. Wheat is the major contributor to land use accounting for the largest component.
The space required by the birds themselves was about 6 sqm for 4 meat (weight 800 grams) chickens for 5 months. This is approximately 1.2 square metres per kilogram of chicken meat per year.
Civic Chicken Producer 1 and production of 1 kg of chicken meat water use cubic metres
In this model 0.17 cubic metres of water are used, primarily in production of feed. This model includes rain water used on site for the 4 chickens to drink.
Note that a big impact seems to be from irrigated sorghum based on CH (Swiss) data. (Aim to re-do the model with Australian data if possible). Manure management contributes an offset by reducing the need for synthetic fertiliser.
Civic Chicken Producer 2 and production of 1 kg of chicken meat: CO2 equivalent emissions version
In this model it is estimated that production of 1 kg of chicken meat leads to 3.97 kg of CO2 equivalent. The major contributor is production of feed for the chickens. More detail about the production of wheat as part of this process is shown in the next diagram.
Electricity used to hatch the eggs also has some impact on CO2 emissions. The cooking process of one hour in a gas oven is not included here, but would only contribute a small component (0.21 kg CO2 equivalent emissions).
Civic Chicken Producer 2 and production of 1 kg of chicken meat: land use. Hectare- years
In this model, 0.003 hectare-years (30 sq metres over one year) are used to produce 1kg meat. Growing the feed produces the greatest impact on land use, especially wheat. To produce 1kg of chicken meat requires 0.003 hectare-years (note: one hectare is 10,000 sq metres or 2.45 acres)
The space taken by the birds themselves is about 0.25 acre (approx 1000 sq m ) to raise approximately 490 kg (140 chickens of size 3.5kg) in one year or about 2sq m per kg meat produced in one year.
Civic Chicken Producer 2 and production of 1 kg of chicken meat: water use in cubic metre(5% cutoff)
In this model, 0.32 cubic metre of water is used, primarily in production of feed. Note that the big impact seems to be from irrigated sorghum based on CH (Switzerland) data which may not be representative for Australia. In the final papers, models will incorporate Australian data. Dam water for drinking and heated Sydney water used in the harvesting process contributes only minimally to the overall usage of water in this model.
Local industrial production of 1 kg of chicken meat and CO2 equivalent emissions
*(10% contribution cut off used as model has so many components)
In this model 2.58 kg CO2 equivalent emissions are produced for one kg chicken meat on the consumer’s table; a further 0.21kg would be produced to cook the chicken in a gas oven for one hour. The main contributor is the feed; there is a small offset due to the use of chicken manure as a fertilizer which offsets the need to use synthetic fertilizers. Car travel by the consumer 5km to buy the chicken from the supermarket accounted for about 5% of the total CO2 equivalent emissions, assuming that the chicken was about 5% of groceries bought at the same time (based on monetary value). If other items were not bought in conjunction with the chicken, this contribution would be considerably increased.
Local industrial production of 1 kg of chicken meat: land use Hectare-years
In this model 0.0009 hectare-years are used to produce 1 kg of chicken meat. The feed production dominates the land use pattern. In terms of land actually occupied by chickens at the grower farms in one year, 1 m2 at grower farm can grow 223.2kg chicken meat (16.9chickens x 5.5 batches=93 chickens @ 2.4 kg each).
Land used at breeder farm, hatchery, processing plant, retail store is not included in the model.
Industrial local production of 1 kg of chicken meat water use cubic metres
In this model 0.18 cubic metres of water are used, primarily in production of feed. This model includes drinking water used on farms for the chickens to drink, modelled as Sydney drinking water- this component is very small compared to water for feed production, but Sydney water is likely to be more contested. Not all farms use Sydney water and other sources would have less impact. Note that the big impact seems to be from irrigated sorghum based on CH (Swiss) data. (Aim to reassess using Aust data if possible)
Civic Lettuce Producer 1 and production of 1 kg lettuce: CO2 equivalent emissions
The model shows production of 1kg of lettuce producing 0.25kg CO2 equivalent emissions. Production of own or industrially produced seeds is quite influential on total CO2 equivalent emissions. Use of seed from industrial production involves tractor use, fertilizers and transport- production of own seed greatly reduces this impact. Likewise, production of own compost and reduction of use of industrial fertilizers is influential.
Civic Lettuce Producer 1 and production of 1 kg of lettuce: land use Hectare-years
The model shows production of 1kg of lettuce takes 3.96 x 10-6 hectare years.
Civic Lettuce Producer 1and production of 1 kg of lettuce: water use in cubic metres
The model shows production of 1kg of lettuce takes 0.004 cu m water. If industrial seeds are used this becomes a major contributor to water use. Home production of seed reduces this impact.
Civic Lettuce Producer 2 and production of 1 kg lettuce: CO2 equivalent emissions
The model shows production of 1kg of lettuce produces 0.08kg CO2 equivalent emissions. This current model does not take account of chickens to provide manure- they produce a by product of eggs (avoiding industrial production) and the manure avoids use of synthetic fertilisers. They also require input of feed.
Civic Lettuce Producer 2 and production of 1 kg of lettuce: land use Hectares per year
The model shows production of 1kg of lettuce uses 1.35 x 1 -5 hectare yrs.
Civic Lettuce Producer 2 and production of 1 kg of lettuce: water use in cubic metres
The model shows production of 1kg of lettuce accounts for 0.004 cu m water.
Local Industrial lettuce Producer 1 and production of 1 kg of lettuce: CO2 equivalent emissions (5% cutoff)
The model shows production of 1kg of lettuce produces 0.32kg CO2 equivalent emissions.
Local Industrial lettuce Producer 1 and production of 1 kg of lettuce: land usein hectares.(0.6% cutoff)
The model shows production of 1kg of lettuce uses 2.0 x 10-5 hectares per year.
Local Industrial lettuce Producer 1 and production of 1 kg of lettuce: water use. (0.6% cutoff)
The model shows production of 1kg of lettuce uses 0.072cubic metres of water.