Latest edition of Nutrient Management Guide RB209 now available

We have published a new version of the Nutrient Management Guide (RB209), which helps growers make the most of organic materials and balance the benefits of fertiliser use against the costs – both economic and environmental.

This year's RB209 marks the first revision since the 2023 ‘golden anniversary’ edition and the 2024 strategic review of the guide.  Based on feedback from over 900 people, the review’s findings both informed the latest revision and prioritised investment in nutrient management research to feed into subsequent editions.

Nutrient use efficiency was identified as the highest priority area by levy payers and RB209 will continue to provide robust, evidence-based information to assist with the reduction of input costs, without compromising yield or quality.

Amanda Bennett, the AHDB Senior Environment Manager who led the 2024 review and 2026 revision, said:

"We have listened to what levy payers need from RB209 and have strengthened activity to provide adaptable guidance to meet the nutrient needs of a wide range of farming situations across the UK.

"While RB209 2026 is based on the latest available evidence, we have also invested in research to address some of the most critical knowledge gaps identified during the 2024 review.

"The conflict in the Middle East has refocused attention on fertiliser inputs and RB209 will continue to help farmers apply nutrients in the right place, in the right amount, at the right time, on a healthy soil."

This year's highlights include:

• Section 1 (Principles of fertiliser use and nutrient management) features improved pH and liming guidance
• Section 2 (Organic materials) accounts better for nutrient cycling. Specifically, it provides improved data on crop-available nutrients from numerous organic materials applied in various situations. The section also includes two new tables on nitrogen availability to crops after anaerobic digestate applications (from both food- and farm-based sources)
• Section 3 (Grass and forage crops) introduces more examples of nitrogen recommendations for different management patterns of grazing and silage
• Section 4 (Arable crops) includes several data refinements and layout improvements

Full details of all the revisions are available on the RB209 updates page.

The RB209 review identified numerous knowledge gaps associated with Section 3.

Earlier this year, we commissioned a review of grass and forage crop information to recommend how to improve this section in subsequent editions and highlight requirements for further research.

The review also highlighted a demand for stronger guidance on cover crops.

Consistency of cover crop information has already been improved in RB209 2026 (across Sections 1 to 4).

We also commissioned several short projects since 2024 to address knowledge gaps.

A key recent finding is that most nitrogen taken up by cover crops is usually released into the soil within two months of destruction, although release can take longer.

Our research is currently tackling the lack of specific information on nitrogen release timings for specific situations, including consideration of destruction methods.

Last year, around 150 farmers and advisors took part in an ADAS-led review of the topic, with most respondents (86%) expressing a 'great interest' in having a practical management tool.

This year, we will continue to fund work with Anglian Water, Southern Water and Wessex Water to develop a simple decision support tree for nutrient management following cover crops.

The tree will account for key variables, such as species (cover crops sown as straights or in mixtures), management timings, crop condition and site-specific factors (e.g. soil type and weather).

We will release results from this work later this year and publish the decision support tree for use alongside RB209 guidance initially.

This year's edition is available to order now for postal delivery from our online catalogue.

Anyone who needs a PDF copy urgently should email info@ahdb.org.uk.

An online PDF edition will be available on our website later this spring.