AHDB-led pilot shows current soil carbon measurement methodologies may be underestimating carbon stocks by a third or more

Initial findings from our pioneering environmental baselining pilot suggest that current carbon accounting methodologies could significantly underestimate the amount of carbon stored in soils, with 30% or more of soil organic carbon on the pilot farms sitting below the commonly measured 30cm depth.

The Environment Baselining Pilot, delivered by AHDB with support from Quality Meat Scotland (QMS) and Hybu Cig Cymru – Meat Promotion Wales (HCC), is working with 178 farms across the beef and lamb, cereals and oilseeds, dairy and pork sectors in England, Scotland and Wales.

It represents one of the most detailed assessments of carbon stocks across British farmland in recent decades.

Using soil sampling to depths of up to one metre where possible, alongside LiDAR scanning of above‑ground features, the project has generated a robust baseline of environmental data.

Over 53,000 soil cores have been collected across more than 5,000 fields, with analysis now underway.

Early findings from the initial 170 farms show that around 95% of estimated carbon stocks on participating farms are held in soils, with the remainder stored in trees and hedges and analysis to date suggests that 30% or more of soil organic carbon stock sits below the 30 cm depth.*

There is also a huge variation between soils. Across the farmland analysed so far, the average soil carbon stock is around 128 tonnes per hectare, but some fields exceed 600 tonnes per hectare.

Farmland in the Cambridgeshire Fens and Somerset Levels have returned the highest values, with deep, organic peat soils showing particularly high carbon stocks.

Chris Gooderham, AHDB’s Environment Director, said:

"We’ve now completed the data collection phase across 170 farms, and the scale of what we’ve gathered is significant. This gives us a much more detailed picture of carbon on farm than we’ve had before. It also demonstrates the value of environmental baselining on individual farms and the valuable role farmers can play in supporting and protecting our environment."

Alongside carbon stock measurements, each participating farm has also completed a carbon audit. These audits estimate greenhouse gas emissions and removals through a carbon calculator and help farmers identify tailored actions for their own businesses.

The next phase of the pilot will focus on understanding the drivers behind differences in soil carbon stocks, including soil type, land use and management practices, and how this can inform future decision-making on farm.

The pilot is continuing to expand, with eight additional farms joining late last year through collaboration with Hybu Cig Cymru – Meat Promotion Wales (HCC), further strengthening the dataset across different farming systems.

We have also established a new Scientific and Technical Advisory Group. The group brings together independent scientific and technical expertise to guide the interpretation, use and communication of the baselining data, helping ensure outputs are robust, evidence‑based and deliver value for levy payers.

We are sharing further insights from the pilot at a series of on‑farm events throughout June, offering farmers and industry stakeholders the chance to explore findings and discuss practical applications.

*The pilot measured the carbon stocks on farms. It did not set out to measure carbon stocks in forests, although some of the farms do have areas of woodland that have been covered by the pilot’s measurements.