Calculating and reducing your carbon footprint

Michael and Tony Ball from Coton Wood Farm, along with Becky Willson from The Farm Carbon Toolkit, explore how to measure and reduce your carbon footprint and make your farm more efficient.

Agriculture’s greenhouse gas emissions

Carbon is often focused on the most, but it actually only accounts for a small percentage of agricultural emissions.

The three main greenhouse gases (GHGs) emissions in agriculture are nitrous oxide, methane and carbon dioxide (CO₂).

Nitrous oxide is impacted by soil management; how manures are managed, stored and applied; sources of fertiliser; application rates and methods.

Methane is impacted by how livestock systems are managed, improving efficiency can reduce methane emissions, how manures and slurries are managed, stored and applied.

Carbon dioxide only accounts for about 5% of total agricultural emissions. Carbon emissions are associated with fuel and electricity use on farm, manufacture and production of feed and fertiliser, and how soils are cultivated. Carbon can be lost when soil is turned over and exposed to the atmosphere.

Agriculture is unique in the ability to be able to pull CO₂ out of the atmosphere and hold it within farms by holding in within hedgerows, trees and forestry areas, and soils. This allows agriculture to offer a climate solution.

By doing a carbon footprint and understanding the positive things, it allows us to change the conversation and see agriculture in a more positive light.

The Carbon Toolkit carbon calculator

The first part of being able to manage carbon on-farm comes by being able to measure it.

The carbon calculator was developed for farmers by farmers and is free for farmers to use. It accounts for soil carbon sequestration and is linked into soil carbon research project to populate models. It allows monitoring of the farm’s footprint annually.

The carbon calculator provides the footprint as CO₂ equivalent, but allows the ability to see different greenhouse gases to understand how much emissions are of each. It allows inclusion of new methane methodology and a new reporting format and user interface developed and was launched in January 2020. 

Calculating your carbon footprint

Interpreting results is a key part of the process as it can be used to evaluate your current position and plan the farm’s strategy for reducing emissions and improving sequestration in the future.

It gives you a baseline and allows you to be more informed and provides evidence to change management. Once you have created your initial report, you can look at the impact of changing different parameters on-farm.

You need to know where you are before you decide where you want to go. Carbon is another way of looking at business efficiency.

The carbon balance is calculated by carbon emissions (from fuels, materials, inputs, crops, livestock, waste) minus carbon lost in sequestration (by trees, hedgerows, non-cropped areas, soil carbon, plus offsets from recycling waste products or renewable energy).

What does your carbon footprint tell you?

Carbon footprint has various different layers and as you delve into the layers you get to understand the figures more.

The headline figure of carbon balance doesn’t really tell you much, especially when you try to compare your results with other farms or previous years.

You can break this down into carbon balance/ha or tonne of product which allows for some comparison. You can also look at emissions and sequestration categories and the percentage of emissions that come from each category, which allows you to identify hotspots, which you can delve deeper into.

The best person to benchmark with is yourself as it shows how far you have come. You can also benchmark against other farmers to allow understanding of potential for change.

Things will change irrespective of your management, as biological systems are dependent on the weather and are outside of your control. 

Results of the carbon footprint at Coton Wood

• Carbon balance at Coton Wood – 4,803.79 tonnes CO₂ equivalent per year. The vast majority of this will be coming from methane and nitrous oxide but is translated into CO₂ equivalent
• Carbon balance per hectare – 15.7 tonnes CO₂e/hectare/year
• Carbon balance per tonne of product (milk) – 0.89 CO₂e/tonne of product
• Carbon balance per litre of milk – 0.96kg CO₂e
• The average carbon footprint per kg of milk is 1.25kg CO₂e – Coton Wood is better than average 

Headline emissions at Coton Wood

Tony and Michael were surprised by the high proportion that livestock was contributing to the overall business.

Livestock emissions aren’t solely from the animals, it also takes into account emissions from manure and any imported feed onto the farm.

Crops takes into account annual crops that are grown on the farm. Inputs are things like fertilisers.

Compared to an arable farm, on average around 60% emissions come from fertiliser use and application, 20% from fuel use and cultivation, 10% from P, K and lime.

On a beef lowland grazing system, around 75% emissions from from livestock, 8–10% from fuels, and the majority of the result from inputs.

Coton Wood has a robotic milking system and has seen a big increase in electricity use since installing the robots. 

Coton Wood carbon emissions breakdown for livestock

Total livestock emissions – 4,121t CO₂e

18% emission from feed – Coton Wood are fed a TMR through the year with a mixture of grass and maize silage. They buy in straights, soya, sugarbeet, distillers, molasses and premix themselves. They use cut and carry in the summer for high yielding cows and low yielding cows go out to graze.

If the soya was switched for UK produced rapeseed meal, the total livestock emissions would fall.

To improve this figure, we need to improve efficiency by focusing on health management and reproductive management. Before cows have calved down and entered the milking herd, they’re producing a lot of emissions but no end product yet.

Optimal health status means they are likely to stay in production for a longer time and the period at the beginning is offset over an increased number of lactations. Good reproductive and fertility management allows the heifer to calve down at 24 months.

Focusing on genetics allows you to select more productive animals. In the future, we will also be able to select for methane production because methane is a heritable trait.

Areas of carbon sequestration

Sequestration can come from hedgerows, woodland, field margins/uncultivated areas and perennial crops which can all be measured by area.

In order to measure soil carbon and how much carbon is being sequestered in the soil due to management, the soil needs to be tested.

There are also offsets included here from recycling or renewable energy generation.

At Coton Wood, they need to be achieving a 0.25% annual increase across 152 ha of grassland and a 0.2% increase across 148 ha of arable land to ‘offset’ all emissions from the farm.

Soil carbon isn’t the be all and end all, but it is a really useful tool in the box that we can use and not only it is providing a climate solution, it’s also increasing the resilience and the performance of the farm. But it’s also really important to look at opportunities to reduce emissions.

Using carbon calculators

Carbon calculators are a really useful tool to look at business efficiency, plan future management and baseline your current position; this provides an alternative lens to look at your business efficiency and operations.

Find one that works for you, it’s an evolving science so none of them are perfect or do everything, but it’s an evolving science and they are moving in the right direction.

We have to start somewhere. We have very ambitious climate targets to reach and a key part of looking and assessing our proximity to net zero is starting by measuring and that’s where carbon calculators can help.