Digestate
What Is Digestate?
Digestate is what's left after slurry passes through a digester — still nutrient-rich, still needing storage, and usable as fertiliser where the rules are met.
6 min readRead Guide
Digestate
What Is the Fertiliser Value of Digestate?
Digestate has genuine fertiliser value, but putting a single number on it would be misleading. Here's what actually drives that value on a real farm.
7 min read · Reviewed September 2026
Quick Answer
Digestate contains useful plant nutrients, but its financial and agronomic value depends on nutrient analysis, crop requirements, storage, spreading and the fertiliser it actually displaces. There's no reliable universal figure, because composition and circumstances vary too much between farms to reduce to one number.
Key Points
- Nitrogen, phosphorus and potassium are all present, but in varying proportions
- Readily available nitrogen makes timing and application method genuinely important
- Feedstock and process both affect what a specific farm's digestate actually contains
- A universal £/m³ value would be misleading — testing is the reliable basis
What nutrients does digestate contain?
Digestate typically contains nitrogen, phosphorus and potassium, along with other nutrients and organic matter, carried over from the original feedstock through the digestion process. The exact balance depends heavily on what went into the digester and how the plant operates.
Readily available nitrogen
A meaningful share of the nitrogen in digestate is typically in a more readily available form — ammonium nitrogen — than the organic nitrogen in untreated slurry. This is agronomically useful because it can be taken up by crops more quickly, but it also means it's more prone to loss through ammonia volatilisation if it isn't applied and managed carefully.
How feedstock affects what you actually get
Digestate composition follows from what's fed into the digester — slurry-only systems produce a different nutrient profile from those supplemented with other feedstock. This is one of the clearest reasons a generic figure for 'digestate value' can't apply across different farms and systems.
Why testing matters more than a published average
Because composition varies with feedstock, process and storage, testing the actual material a farm produces gives a far more reliable basis for fertiliser planning than relying on a general published average. This feeds directly into a farm's nutrient management plan, the same way any other organic manure or slurry analysis would.
Storage and application method
How digestate is stored, and how it's applied to land, both affect how much of its nutrient content is actually retained and used by the crop rather than lost. Covered exposure, timing relative to crop demand, and application method (such as low-emission spreading techniques) all influence the real-world value of a given analysis.
Fertiliser displacement — the real financial question
The genuine financial value of digestate on a specific farm comes from what bought-in fertiliser it displaces, not from an abstract nutrient content figure. That depends on the farm's cropping, its existing fertiliser programme, and how well the digestate application is timed against actual crop demand — worth working out with an actual nutrient management plan rather than a rule of thumb.
Why a universal £/m³ value would be misleading
Fertiliser prices move, nutrient analyses vary between farms and even between batches, and the value of any given nutrient depends on what it's replacing. Publishing a single monetary figure for digestate would imply a precision that doesn't reflect how differently this plays out on different farms — which is why this guide explains the factors involved rather than offering a number to plan around.
Frequently Asked Questions
Sources
Related AD Guides
Digestate
Nitrogen in Slurry During AD
AD doesn't remove most of slurry's nitrogen — it converts some of it into a form crops can use more readily, which changes how it needs to be managed.
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Can You Spread Digestate on Farmland?
Yes, where the relevant requirements are met — but the position depends on feedstock, waste status and jurisdiction, and England and Scotland aren't the same.
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Is Digestate Better Than Slurry?
Digestate isn't simply superior to slurry across the board — digestion changes the material in specific ways, and its value depends on what a farm needs from it.
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PLANNING AN AD INSTALLATION?
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