Early indicators to monitor changes in soil health: evidence to update guidance for UK farmers

The soil health scorecard lets you track changes to soil health on a rotational basis (every 4 to 5 years).

It uses practical indicators of the physical, chemical, and biological condition of soil and benchmark values to highlight potential issues and ways to address them.

This desk study identified additional methods to monitor soil health changes more regularly (e.g. on an annual or seasonal basis).

A initial list of ten indicators was identified at the project-proposal-development stage based on recent expert reviews:

1. Earthworms (adult count).
2. CO_2.
3. Potentially mineralisable nitrogen (PMN).
4. Crop rooting.
5. Soil carbon fractions.
6. Soil food web.
7. Phospholipid fatty acids (PLFA).
8. Enzyme assays.
9. Functional gene analysis.
10. Aggregate stability.

Indicators were evaluated based on their relationship with key ecosystem services:

• Food, fibre and biomass production
• Soil carbon storage for climate mitigation
• Nutrient cycling, including the provision of nitrogen, phosphorus and potassium to crops
• Water regulation, including flood alleviation and runoff/erosion mitigation
• Drought mitigation

Indicators were also evaluated based on:

• Sensitivity to management change
• Link to changes in soil health
• Availability of robust, UK-relevant data
• Spatial variability and numbers of samples required to represent an area
• Cost to the client
• Usefulness for farmers

The researchers used a ‘logical sieve’ framework to provide an objective and quantitative means to rank the candidate indicators.

An industry reference group followed a structured, iterative survey approach (Delphi method) to reach a consensus on the top four indicators.

There was a clear consensus to exclude soil food web methods due to some inconsistent and variable results and the lack of evidence indicating that these methods are sensitive to recent management changes.  

Two stakeholder workshops were held to sense-check the suitability of the indicators with end-users, which emphasised that farmer-led methods are preferred.

Based on an evidence-based review, aggregate stability was the highest ranked indicator, followed by crop root architecture, active carbon and potentially mineralisable nitrogen.

Crop rooting was viewed as an emerging and accessible farmer-led method that may offer good sensitivity to management but requires standardisation and development of interpretation frameworks.

As a result, three indicators were selected to improve guidance. 

1. Aggregate stability

• Tests the strength of the building blocks of the soil
• Links to crop yield, resistance to soil erosion and compaction, and water availability and movement
• Outcome of active soil biology
• Indicates changes in soil health more rapidly than soil organic matter changes
• Simple and easy methods available for use on farm

Measuring aggregate stability to detect early changes in soil health

2. Active carbon

• Different pools of organic matter decompose at different rates
• Permanganate oxidisable carbon (POXC) measures the active carbon (C) pool in the soil
• POXC is sensitive to management and may provide a more rapid indication of the effects of management changes on soil health, compared with soil organic matter measured by loss on ignition (LOI)
• Assessed by a rapid and effective method in the laboratory

Measuring active carbon to detect early changes in soil health

3. Potentially mineralisable nitrogen

• Tests the ability of the microbial community to supply plant available nitrogen
• Outcome of active soil biology
• Influenced by agricultural management practices
• Indicates changes in soil health more rapidly than soil organic matter changes
• Widely offered test from commercial laboratories

Using potentially mineralisable nitrogen to measure soil health

Non-AHDB funds

The project secured £9,750 (in-kind funds) from collaborating companies providing expertise and perspectives on soil health analysis:

• Vedant Carbon: £3,750
• Hill Court Farm Research: £3,000
• Frontier Agriculture: £1,500
• Eurofins: £1,500

The workshop

Arable and livestock farmers/advisors took part in an online workshop on 10 February 2026 to discuss the relevance and usefulness of potential early indicators of soil health and direct the project’s next steps.

Read an article about the workshop's main findings

Also

Read a news article about the main outcomes from this research

Watch a presentation that covered this project (Agronomy Conference 2025)

Providing answers to your questions

This research project was funded via a levy-payer-led commissioning process.

View the original research call for this work