Ways to reduce dairy greenhouse gas emissions to hit targets
© Tim Scrivener Dairy farmers can make some easy strides to improve their carbon footprint as pressure mounts to reduce greenhouse gas emissions from farms.
The NFU has set a target for farming to become net zero by 2040 – 10 years ahead of the governments target.
Although that might seem some time away, farmers need to start identifying the risk points for high emissions on their farm and embedding carbon footprinting into their business plans now.
That was the message at Dairy Tech 2020, where John Allen from Kite Consulting warned environmental challenges would not go away.
See also: 7 ways to flood-proof soils and improve drainage
He said: “We need to address environmental concerns from consumers. We don’t want people to feel guilty about consuming dairy because it’s ‘bad’ for the environment.
“We have to give consumers peace of mind and we can do something about it that can be good for the bottom line.”
Speaking to Farmers Weekly, Promar International’s head of sustainability, Tom Gill, reiterated this point:
“Not enough farmers know what the risk points are on their farm. Too many farmers are at the lower end of performance and are not addressing the simple issues that can make a big difference.”
Methane and nitrogen oxide are two of the most harmful greenhouse gases (GHG) on dairy farms and are the main ones to focus on, according to Mr Gill.
Almost 40% of methane is produced as a result of fermentation in the rumen, with the rumen and feed use contributing to more than 60% of the overall environmental effects on dairy farms.
While Mr Gill stresses there is no silver bullet to help reduce emissions, he did set out some short-term wins that can help farmers cut GHG.
- Find out what your carbon footprint is. If you are not in a designated supply chain and do not have a carbon footprint for your farm, do an audit. There are free tools that can help you do this, as well as paid-for services specific to dairy farms.
- Once you know your carbon footprint, find out what is contributing to that number.
The good news is many farmers will already be making good headway to improve short-term efficiencies and reduce emissions.
Ways you can do this include:
Herd management
Calving pattern and pregnancy rate If heifers are failing to make it into the milking herd, you will be generating unnecessary emissions. Target See The AHDB Dairy website for system-specific targets
Tackle mastitis The average mastitis rate in the UK is about 30%. It has a negative effect on efficiency and GHG emissions. Target A mastitis incidence rate of no more than 30 cases for every 100 cows a year.
Cull for poor fertility On average, 15% of cows are culled for fertility issues in the UK, with fertility having a larger effect on GHG emissions.
Better cow longevity equates to lower replacement rates and fewer heifers, which will reduce emissions. Target Average calving interval of 365 days and a failure-to-conceive culling rate of 6%.
Genetics and fertility Aim to reduce waste and improve efficiencies such as feed conversion-to-milk yield ratio by harnessing technology like genomics to accurately identify the top-performing animals in your herd.
Breed these to sexed semen and put lower-genetic-merit animals to beef to improve cashflow. This means more can be created from fewer cows.
Age at first calving The older the animal is at calving, the more feed she will consume and emissions she will produce before she is creating any value (putting milk in the tank). Target 24 months.
Feed
Feed rate a litre is a bigger driver of GHG emissions than yield a cow.
Figures from Mole Valley Farmers suggest reducing fibre levels can lower emissions. For example, a diet of 32% neutral detergent fibre (NDF) versus a diet of 40% NDF will produce about 5% less methane.
This is because the types of micro-organisms in the rumen that digest fibre are the ones that produce more methane.
Matt Witt from Mole Valley Farmers says farmers should be cautious when reducing fibre and should not go below 30% NDF, as this can cause digestive upsets.
Research by Alltech found £216 a cow is lost through feed waste on average. This is mainly lost through poor feed conversion efficiency. From silage alone, on average, £57 a cow a year is wasted.
Read more: Tips on reducing feed waste
Land management
- Maximise home-grown feed
- Rely less on palm and soya
- Increase output/ha and forage quality
Kite Consulting predict dairy producer numbers will fall from 12,000 to just under 8,000 by 2030, with the biggest proportion of producers expected to exit in 2024-25 to save the cost of having to meet permit requirements.
“That would create opportunities for those that remain, because land will become available for them to take on which means [farmers] can keep more cows or spread more slurry,” said Kite’s John Allen.
Permits would likely see farmers having to ensure they have more land for slurry spreading, increased slurry storage capacity to meet closed spreading periods, and slurry may have to be acidified to reduce ammonia emissions.
A comparison of farmers with a low, average and high carbon footprint |
|||
|
|
Lower 10% |
Average |
Higher 10% |
|
Carbon footprint (kg carbon dioxide equivalent/litre FCM) |
1.096 |
1.343 |
1.777 |
|
Milk yield (litres) |
8,538 |
8,068 |
7,547 |
|
Herd size |
184 |
186 |
186 |
|
Feed rate (dry feeds as kg/litre) |
0.34 |
0.37 |
0.44 |
|
Plus moist feeds as concentrate equivalent |
0.03 |
0.04 |
0.06 |
|
Soya bean meal users (as straights) |
7% |
30% |
63% |
|
Cows leaving the herd (percentage of herd) |
28% |
27% |
27% |
|
Cows dead (leaving for no value) |
17% |
22% |
29% |
|
True flying herds (number of flying herds out of 41) |
3 |
10 |
0 |
|
Heifers on farm (as percentage of average cow numbers) |
57% |
67% |
80% |
|
Growing maize |
76% |
63% |
44% |
|
Grassland N use (kg/ha) |
109 |
133 |
138 |
|
Source: Promar International |
|||
What’s coming down the line and what does it mean?
The Clean Air Strategy 2019 sets out the action the government will take to reduce ammonia emissions from faming in line with clean air targets. They include:
- Regulate to reduce ammonia from urea.
- Incorporate manures within two hours of spreading.
- Must use low-emission spreaders by 2025.
- Must cover slurry stores by 2027.
- Standards for new livestock housing.
- Regulate to reduce emissions from fertilisers (based on advice from an expert group).
- We may see an extension of environmental permitting to dairy and intensive beef farms. The current plan is to introduce this to the largest dairy farms by 2025.
See also: Clean Air strategy details
Key figures about GHG emissions in dairy farming
- Dairy production is responsible for 3% of global GHG emissions
- Dairy production accounts for 41% of global livestock emissions
- UK dairy farms are responsible for less than 2% of the country’s total emissions
- Per litre of fat-corrected milk, the average carbon footprint for milk production is just 1.25kg of carbon dioxide equivalent
(Source: RABDF’s Greenhouse Gas emissions leaflet)
Case study: Grosvenor Farms, Cheshire
Farm facts
- Milks 2,500 cows
- Yields 12,500 litres at 4% butterfat and 3.45% protein
- 70% of milk sold to the Tesco Sustainable Dairy Group, with the remaining 30% going to Muller Direct
- Farms just under 2,400ha; 11% of which is in biodiversity schemes
Grosvenor Farms has reduced carbon emissions by 16% on average across its 2,500-cow dairy enterprise in Cheshire.
The national average for UK dairies is 1.25kg carbon/litre of fat-corrected milk, with the worst dairies hitting 2.5kg.
But at Grosvenor, this figure sits at just 1.02kg.
Below, livestock manager David Craven explains how the farm has reduced emissions so far:
- A 72ha area around the River Dee has been put into arable reversion. Nutrient application is limited and no pesticide is allowed.
- They have installed 250kW of solar panels and export surplus energy to the grid.
- They use a heat-recovery unit and borehole water gets used multiple times; for milk cooling, drinking water, parlour cleaning, flood washing and sand separation to dilute slurry.
- The best genetics are used to breed superior animals. Sexed semen is used on all maiden heifers and the top 20% of cows. All heifers get genomic testing and the farm deselects at weaning based on health status.
- Calving down at 23 months so cows have a longer, more productive life. This is achieved by good youngstock daily weight gains of 0.9kg.
- Continuously recycling sand bedding using a sand separation system
- 97% of all forages grown just receive manure. Manure is separated from sand to create solids; it is analysed and applied to land with a rear-discharge spreader. This also reduces nitrogen use.
- Use min-till and only plough after seven years to get rid of weeds. This has helped increased organic matter to 5.26% – the UK average is 1.76% for cultivated soils.
Next steps
Grosvenor Farms hopes to further improve soil organic matter by 0.4% each year and have just done a carbon budget with SAC Consulting with the aim of reducing emissions to just 880g/litre of fat-corrected milk.
It believes this can be achieved by using manure more efficiently on far-away land, using more forage and reducing bought-in feed.
Mr Craven added: “Now we are up to full numbers, we should see a dilution effect. Ultimately, where we will gain is if we improve yield a cow, but we haven’t accounted for that this year.”
In future years, the farm hopes to improve yield and constituents, health and cow longevity, use more renewable energy and explore the use of methane inhibitors in feed as it drives to lower emissions.
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