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What do my carbon calculation results mean?
Unsure on what your carbon calculation or footprint results mean? Read here to find out where you compare to industry averages.
Arable
Emissions from conventional arable systems are comprised primarily of direct nitrous oxide emissions, from the application of synthetic and organic nitrogen-based fertiliser to the land. Certain agrochemicals such as urea, gypsum, and dolomite, emit carbon dioxide directly.
Other emission sources include embedded emissions associated with production of fertiliser and other agrochemicals, emissions of nitrous oxide from crop residues, and fossil fuel and electricity usage for fieldwork, crop drying, and storage.
Emissions are typically driven by application rate of inputs, though resulting higher yields may offset this in terms of emissions intensity. Soil type is important, with sandy soils typically offering lower fieldwork emissions, but lower yields. Heavier clay soils are likely to become wet, which increases nitrous oxide emissions. Better practices can lead to soil carbon sequestration which may offset around 50% of the footprint - reduced or zero tillage; cover cropping; application of organic manures; and retention of crop residues. All will contribute to an increased potential for sequestration, while heavier tillage and higher removal of residues will lead to soil carbon loss.
Emissions per hectare for arable products are typically in the range of 1-4 tonnes carbon dioxide equivalent per hectare, while emission intensities can range from <100kg carbon dioxide equivalent per tonne of product for higher yielding forage crops, to >700kg carbon dioxide equivalent per tonne of product for lower yielding crops, such as oilseed rape. A typical UK range for wheat production varies from 200-400kg carbon dioxide equivalent per tonne of product, with global ranges extending up to >2000kg carbon dioxide equivalent per tonne of product.
Beef
Emissions from beef production are composed primarily of methane, from enteric fermentation and manure management, as well as nitrous oxide, from manure management and fertiliser applications to grazing land.
Fossil fuel and electricity may be used in supporting the enterprise, and purchased or homegrown feeds used to support the animals when housed, may also form a significant element of the footprint.
Emissions from beef production vary widely on a per-hectare basis, depending largely on the system type, and land quality. Finished beef emission intensity ranges from 12-30kg carbon dioxide equivalent per kilo carcass weight for UK systems. Globally, the range can exceed 100kg carbon dioxide equivalent per kilo carcass weight. For the rear-finish element of the system, emission intensities for live weight gained are typically around half of the lifetime emissions (6-15) kg carbon dioxide equivalent per kilo carcass weight, owing primarily to faster growth rates and a lack of breeding animal overheads.
Dairy & Milk Production
Emission sources from dairy systems are similar to those for beef, with enteric fermentation and manure management being significant contributors. Depending somewhat on the intensity of the dairy system, feed production emissions and manure management may be proportionally more than beef systems. Efficiency-related production KPIs (e.g. milk yield) are typically influential in driving the emissions intensity.
Milk is typically produced in the UK in the range of 0.7-1.7 kg carbon dioxide equivalent per litre, - results outside of this range are not uncommon and do not necessarily imply poor management. Globally, emissions from milk production can range up to 4.4 kg carbon dioxide equivalent per litre.
Eggs
Emissions from layer systems typically focus around management of manure (producing methane and nitrous oxide), fuel and electricity usage, and purchased feeds. Manure management strategy, feed and electricity sourcing, and feed conversion ratios typically are the most influential in the magnitude of an egg's footprint.
Eggs are typically produced at approximately 1.3-2.9 kg carbon dioxide equivalent per kilo
in the UK, and global averages reach up to 6.5 kg carbon dioxide equivalent per kilo.
Grasslands
Permanent grassland emissions contain similarities with the arable and horticulture system. The key factors are broadly input focused (i.e physical commodities utilised in management, such as fertiliser, agrochemicals, electricity and fuel).
Agricultural product emissions including fertiliser will, as with arable systems, include embedded and application components. Similarly fossil fuel and electricity usage for fieldwork, crop drying and storage will also contribute to the footprint. These depend on the type of product/ fuel type/ electricity source and scale with quantities used. For extensive grasslands, limited inputs will often mean footprints may be fairly insignificant.
The location of farms plays a role in the footprints of permanent grasslands contained within them. Spatial data is used including precipitation, altitude, and pH to model grass growth. The management of grassland and grazing also plays a significant role. Removal or grass through cuts and grazing take carbon out of permanent grassland systems with higher intensity grazing and more frequent cutting increasing the impact. Grassland management, productivity and biomass turnover are combined to create a picture of carbon inputs and exports from the system.
For the UK emissions intensities for a grassland with no inputs are between -0.03 and-0.61 t CO2 eq ha-1 yr-1. When impacts of inputs are factored in the range varies more widely between -0.6 and +4 t CO2 eq ha-1 yr-1 being typical.
Perennials
Emissions from perennial systems are comprised primarily of direct nitrous oxide emissions from the application of synthetic and organic nitrogen fertiliser to the land. Certain fertiliser/agrochemicals, such as urea, gypsum and dolomite, also emit CO2 directly. Other emissions sources include the embedded emissions associated with the production of fertiliser and other agrochemicals, emissions of nitrous oxide from crop residues (such as woody biomass from pruning or discarding fruit), and fossil fuel and electricity usage for fieldwork, crop drying and storage.
Emissions are typically driven by the application rate of inputs and residues management, though resulting higher yields may offset this in terms of emissions intensity.
The carbon sequestration is split among two components in Sandy. The soil carbon stock change and the biomass stock carbon change. The first component includes the accumulation of the soil carbon stock from the decay of the fine roots system of the perennials crops, the carbon inputs from residues and the inter-row management types. The second component includes the carbon accumulation into woody biomass and root systems. Note that these two components can be a source of emissions instead of a sequestration source depending on the management (this is more common on arable and horticulture land).
Sequestration per hectare for perennial products is typically in the range of 10-20 tonnes CO2e hectare-1, while systems with high biomass such as Miscanthus can range around 30 tonnes CO2e hectare-1.
Pigs
Emissions from pig meat production follow a similar pattern to egg production, with management of manure, fuel and electricity usage, and purchased feeds forming the majority of the footprint.
Despite being monogastric, pigs produce some enteric methane, though this is in much smaller quantities than a correspondingly sized ruminant system. Mitigation practices targeting these main sources (e.g. manure management; feed sourcing) will have the greatest impact on pig systems.
In the UK, pork is typically produced in the region of 2.7-6.3 carbon dioxide equivalent per kilo carcass weight, though this can vary widely. Globally, emissions can range up to 20kg carbon dioxide equivalent per kilo carcass weight.
Sheep & Lamb
As ruminants, emissions from sheep production are similar to emissions from beef production, though the former have typically a lower reliance on housing and supplementary feed places a heavier emphasis on enteric emissions of methane. Variability in stocking rates also means that per-hectare emissions vary widely.
Sheep and lamb meat is typically produced at around 12-28 kg carbon dioxide equivalent per kilo carcass weight in the UK. Globally, emission intensities range up to 56 kg carbon dioxide equivalent per kilo carcass weight. For systems without breeding stock, it may be possible to achieve emission intensities of 6-14 kg carbon dioxide equivalent per kilo carcass weight, for live weight gained in this part of the system.
Woodland
Woodlands sequester carbon though the conversion of atmospheric carbon dioxide to long-lived woody biomass through the process of photosynthesis. Trees do not grow indefinitely, however, felled wood that is not burned may, if treated correctly, act as a carbon sink for hundreds of years after the death of a tree.
Semi-natural woodlands on farmlands typically sequester in the range of 3-5 tonnes carbon dioxide equivalent per hectare for the majority of their lifetimes. The exact amount depends on the tree species, management, and growing conditions (for example: altitude, climate, and soil may all impact growth rates)
Very young and very old trees sequester considerably less carbon that this range, and some slow-growing hardwood species such as beech or oak, may take around 30 years from planting to get close to these typical sequestration rates.