Improvements to the methodology of the Farm Carbon Calculator mean you can now better capture the detail of livestock management on your farm. More detail in accounting for livestock management practices means both improved accuracy of reporting and better evidencing of efforts to reduce emissions.
What’s changed?
Manure management options
Instead of selecting from just four options for livestock manure management, there are now 9 categories of manure storage with a variety of further amendments and actions associated that may reduce emissions on farm. Full details of the options and what these mean can be found on our Manure Storage Systems guide.
Diet type
Where you have the time and information available to provide detailed information about the type of diet your livestock consumes, it is now possible to use the Farm Carbon Calculator to gain a higher accuracy estimate of enteric methane emissions. This can have a particularly marked effect on the emissions resulting from e.g. a grass-fed vs compound-fed animal. The detailed methodology relies on dry-matter-intake (DMI) but if you don’t know this, we have a Guide to DMI to help you convert forage and “as-fed” weights to DMI.
If you don’t want to enter so much detail, the Farm Carbon Calculator will use the UK GHG inventory default assumptions for livestock diets and consumption.
How will the changes affect my report?
We know it’s important for year on year carbon reporting to maintain consistency. For this reason, legacy reports won’t be automatically transferred into the new livestock calculation.
If you decide to use the new calculation method, this will improve the accuracy of your results. For the majority of reports it will also reduce emissions because most of the previous defaults were based on the highest emitting options in each category. The new options are considered “mitigation measures” allowing for a reduction in the assumed emissions of greenhouse gases compared to a conventional manure management method or livestock ration.
At the end of this blog, we have summarised a few examples of how a report might look with the simplified and more detailed methodologies.
Do I need to do anything?
If you are creating a new report, you will automatically be shown the new calculation methodology but if you don’t have enough information to hand, you can fall back to the simpler method. For existing reports, there a number of options available: you can either manually update each livestock entry or “Migrate” all entries within a report. We have a full guide to switching to the new calculation method:
Guide to updating your reports containing livestock
Manure and slurry applications (spreading)
The main change for livestock farms will be that you need to enter any manure or slurry spreading (whether imported or produced by your own animals) under the Crops > Organic Fertility Sources section of the Calculator (as pictured below).
What if I exported manure or slurry?
You need to account for any storage of manure and slurry on your own farm. So if it remains on farm for 1 month, you need to select the appropriate option for that livestock entry.
You do not need to account for the manure or slurry storage once it has left your farm. You do not need to account for the spreading of that manure on somebody else’s land.
What if I want to keep my report the same?
To ensure your original report remains unchanged, we would recommend locking it. You can do this by selecting your report from your dashboard and then selecting the “Lock” report button at the top right hand of the screen:
You can copy your report. Copying a report leaves the original report with the legacy data in the livestock section, but updates the copy of the report transferring the livestock into the new calculation method. To copy, find your report in your dashboard under “My Reports” and then click the copy icon for that report:
You could then directly compare these reports to see how emissions estimates have changed. We have aligned the old animal waste management options with the new manure storage options to allow this transfer, but some assumptions on systems have been made and we would encourage you to check the manure storage options to see if there is an option more relevant for your system.
Why does the Calculator keep changing?
Sometimes the calculations underlying your report change because of an improved understanding of biological systems or a re-interpretation of the available evidence. In a developing field like agricultural carbon footprinting, working with other organisations to make sense of the available evidence and international guidance within the UK context can help us identify areas where calculations can be improved. This is why we continue to seek pre-competitive collaborations with other companies and research organisations (to find out more about our projects and harmonisation work).
Can I get help?
Contact Michael Brown at [email protected]
What kind of change in emissions can I expect?
The rest of this blog will dig into some comparisons of what might change for different types of livestock.
We have focussed on the management practices that result in the biggest change in emissions compared to the simpler (old) methodology. The comparisons here include only enteric methane emissions and manure methane and nitrous oxide emissions; the areas that now have more detail in accounting for livestock. These comparisons do not include emissions embedded in the production of feedstuffs or bedding since these have not changed as a result of the recent methodology update.
Comparison 1 – dairy cattle, grass-based
In this example, emissions from 100 head of dairy cattle in each category in a 100% grass-based outdoor system are compared using the old and new methodology. Being able to take their detailed manure management and diet type into account with the new methodology would reduce livestock-related emission by 23.5% for dairy cows in this system.
Comparison 2 – sheep outdoor year round
Here we have used 100 head of each category of sheep, assuming 80kg mature weight and 30kg lamb average weight. Being able to take their detailed manure management and diet type into account with the new methodology slightly increases livestock-related emissions for ewes by 11.3% for example. Sheep are the only category of livestock for which the new detailed methodology shows an increase in emissions but it will not be the case for all sheep enterprises. The difference is dependent on manure management and diet of the flock in question.
Comparison 3 – 100% grass-fed beef
In this example, emissions from 100 head of each beef cattle category in a 100% grass-based outdoor system are compared using the old and new methodology. Being able to take detailed manure management and diet type into account with the new methodology would reduce livestock-related emission by 15.3% for beef suckler cows and 7.2% for beef finishing steers in this system, all else being equal.
Comparison 4 – beef cattle with different types of manure management
The following is a comparison of the same 100 beef cattle (all with the same liveweight of 450kg and assumed diet) but with 100% of their manure managed under the available options. This demonstrates the difference in emissions (for beef cattle) from the different manure management options. The magnitude of difference in emissions and management options available varies between different livestock types.
