Looking for reliable biofertilizer information? This resource list brings together guidance on microbial biofertilisers, anaerobic digestion digestate, nutrient planning, certification and agricultural use.
Start with the definitions and examples below, then use the directory to find resources relevant to your crop, farm or anaerobic digestion project.
Biofertilizer is the US spelling; biofertiliser is customary in British English. Both appear in this guide because you will encounter both when searching technical publications.
Originally published in September 2018. Substantially revised in October 2026.
Biofertilizer Resource List: Key Takeaways
- Biofertiliser has two relevant meanings: a microbial preparation that helps plants access nutrients, and—in the UK anaerobic digestion sector—digestate certified under the Biofertiliser Certification Scheme.
- Common microbial examples include Rhizobium, Azotobacter, Azospirillum, phosphate-solubilising microorganisms and mycorrhizal fungi.
- Digestate, compost and microbial inoculants have different roles. Compare their nutrient contribution, biological function and suitability for the intended use.
- Digestate nutrient value varies. Use representative analysis and a crop nutrient plan rather than assuming a fixed fertiliser replacement rate.
- UK certification requires more than a reference to PAS 110. Check current BCS Scheme Rules and the applicable national end-of-waste framework.
- Use the directory below for definitions, research, nutrient guidance, certification documents and sampling information.
1. What Is a Biofertilizer?
In its microbial sense, a biofertilizer is a preparation containing beneficial living microorganisms that help plants obtain nutrients. Depending on the organisms involved, it may support biological nitrogen fixation, make phosphorus more available or help roots access soil nutrients.
The FAO introduction to biofertilisers provides a starting point for this meaning of the term.
In the UK anaerobic digestion industry, biofertiliser also has a certification context. The Biofertiliser Certification Scheme uses the term for digestate certified under its quality and end-of-waste arrangements.
These meanings should not be treated as interchangeable. A microbial inoculant is selected for its biological functions. Digestate supplies nutrients and organic material; its agricultural value does not depend on proving that it acts as a formulated microbial inoculant.
2. Biofertilizer Examples: Names and Functions
The following list covers common microbial biofertiliser groups. These are organism groups or functional categories, rather than endorsements of commercial brands.
| Example | Main function | What to check |
|---|---|---|
| Rhizobium and related rhizobia | Fix atmospheric nitrogen through symbiotic associations with suitable legume roots | Compatibility between the inoculant and the intended legume |
| Azotobacter | Free-living bacteria capable of biological nitrogen fixation | Strain identity, product quality and evidence for the intended use |
| Azospirillum | Root-associated bacteria used for nitrogen fixation and plant growth promotion | Evidence for the particular strain, crop and growing conditions |
| Phosphate-solubilising microorganisms | Help make some soil phosphorus more available to plants | Soil conditions, strain identity and relevant field trials |
| Arbuscular mycorrhizal fungi | Form associations with roots that can improve access to soil nutrients | Crop compatibility and suitability for the existing soil conditions |
| Microbial consortia | Combine organisms selected for complementary nutrient functions | The organisms included and evidence for the complete formulation |
For background, consult the FAO resources on biological nitrogen fixation and beneficial soil microorganisms.
Product performance depends on more than the microorganism’s name. Look for evidence relevant to your crop, soil and management system, together with storage instructions, shelf life and application guidance.
3. Biofertiliser, Digestate and Compost: What Is the Difference?
These materials can all contribute to soil fertility management, but their principal functions differ.
| Material | What it is | Main role |
|---|---|---|
| Microbial biofertiliser | A preparation containing selected beneficial microorganisms | Supports nutrient availability or uptake through biological activity |
| Anaerobic digestate | Material remaining after anaerobic digestion | Supplies nutrients and, depending on the fraction, organic matter |
| Compost | Organic material stabilised through aerobic decomposition | Adds organic matter and contributes nutrients |
| Combined products | Products combining nutrient-bearing materials and selected microorganisms | Depends on the formulation and demonstrated performance |
Compost and digestate should not automatically be described as microbial inoculants. Equally, a microbial inoculant should not be assumed to supply the same quantity of nutrients as a nutrient-bearing fertiliser.
The Three Common Forms of Digestate
Digestate is commonly handled as:
- Whole or mixed digestate: unseparated material containing liquid and suspended solids.
- Separated liquor: the liquid fraction following mechanical separation.
- Separated fibre: the solids-rich fraction following separation.
Separation redistributes nutrients between fractions. Obtain an analysis representative of the actual material being supplied or applied.
For more detail, read our guide to what digestate is. For field management, see our digestate fertiliser application guide.
4. Biofertilizer Resource List: Definitions and Research
Resource 1: FAO Introduction to Biofertilisers
Best for: Understanding the microbial meaning of biofertiliser.
The Food and Agriculture Organization of the United Nations introduces biofertilisers as biological inputs using beneficial microorganisms to improve nutrient availability and uptake.
Read the FAO introduction to biofertilisers.
Resource 2: FAO Beneficial Soil Microorganisms
Best for: Background on microorganisms, roots and nutrient acquisition.
This resource discusses beneficial root associations and soil biological management. Use it to explore the biological principles behind microbial inoculants.
Explore beneficial soil microorganisms.
Resource 3: ICAR Biofertiliser Research and Formulations
Best for: Examples of microbial technologies developed through agricultural research.
The Indian Council of Agricultural Research publishes information about microbial biofertiliser formulations and their intended nutrient functions.
For example, its KASHI AZOBC consortium combines organisms selected for nitrogen fixation, phosphorus solubilisation and potassium mobilisation. This is a research example, rather than a recommendation for every crop or country.
Browse ICAR biofertiliser resources or read about the KASHI AZOBC consortium.
5. Biofertiliser Resources: Certification and Quality
Resource 4: Biofertiliser Certification Scheme
Organisation: Renewable Energy Assurance Ltd (REAL)
Best for: Understanding quality-assured digestate in the UK.
The scheme provides certification arrangements covering PAS 110, the BCS Scheme Rules and relevant national end-of-waste requirements.
Start here when checking what a supplier’s certification means or investigating certification for an anaerobic digestion plant.
Visit the Biofertiliser Certification Scheme.
Resource 5: BCS Scheme Rules and Technical Documents
Best for: Operators, advisers and purchasers checking certification requirements.
The document library contains Scheme Rules and supporting technical positions. Consult the current versions rather than relying on an old downloaded copy or a summary in an article.
Resource 6: Certification Marks and UK National Requirements
Best for: Checking requirements for the nation where digestate will be supplied and used.
BCS identifies separate conformity marks and end-of-waste frameworks for England, Wales, Scotland and Northern Ireland. These are not one identical UK-wide arrangement.
A reference to PAS 110 alone does not establish every condition applying to product status, supply or use. Check the relevant national framework and certification scope.
Read the BCS certification mark guidance.
Resource 7: Sampling and Laboratory Guidance
Best for: Producers arranging representative sampling and certification testing.
BCS publishes guidance on sampling, laboratory paperwork and technical requirements. Certification testing should follow the applicable scheme procedures.
Farm nutrient planning also requires analytical information representative of the digestate actually supplied.
Browse BCS technical guidance and laboratory testing information.
Resource 8: Physical Contamination Guidance
Best for: Finding scheme guidance on plastics and physical quality.
The BCS guidance library includes information on plastics contamination reporting and limits. Use the current documents when assessing scheme requirements.
Find BCS contamination and quality guidance.
6. Nutrient Planning and Digestate Application Resources
Resource 9: AHDB Nutrient Management Guide RB209
Best for: Crop nutrient planning and understanding the contribution of organic materials.
Section 2 covers materials including digestate, manure and compost. AHDB identifies a March 2026 update to Sections 1–4.
Read Section 2 alongside the introductory guidance and the section relevant to your farming enterprise. Published typical values support planning but should not be mistaken for an analysis of a particular delivery.
Access RB209 Section 2: Organic materials.
Resource 10: Digestate Explained
Best for: Readers new to anaerobic digestion.
Our introductory guide explains where digestate comes from, its composition and its potential uses.
Resource 11: Using Digestate in Agriculture
Best for: Moving from background research to practical farm management.
Our agricultural guide discusses nutrient supply, storage, application planning and environmental risks. Use it alongside current official guidance and advice relevant to your holding.
Read: Digestate fertiliser and its agricultural use.
7. Choosing a Biofertiliser: Questions to Ask
Begin with the task you need the product to perform. Supporting legume nodulation, supplying nitrogen and increasing soil organic matter may require different products and management decisions.
Before Purchasing a Microbial Inoculant
- Which organisms and strains does it contain?
- What independent evidence supports its use on your crop?
- Are the trial conditions relevant to your soil and farming system?
- What are its storage conditions and expiry date?
- How should it be applied, and are there compatibility restrictions?
Before Purchasing or Applying Digestate
- Is it whole digestate, separated liquor or fibre?
- What feedstocks were used?
- Is a recent, representative nutrient analysis available?
- What certification and regulatory status apply to the material?
- How will it fit the crop nutrient plan?
- Can it be stored, transported and applied appropriately?
- Does its expected nutrient value justify delivery and application costs?
Compare products by their expected contribution to the farm’s crop and soil management plan, supported by analysis and evidence.
8. Quality and Environmental Considerations
Calling a product biological, natural or organic does not establish that it is suitable for every crop or situation.
For digestate, check nutrient content, physical quality, relevant hygiene requirements and the conditions applying to its intended use. Consult the BCS guidance library for scheme information.
For nutrient planning, use RB209 Section 2. Our agricultural digestate guide discusses how storage, timing and application practice affect nutrient value and pollution risks.
For microbial inoculants, check product identity, viability, storage requirements and evidence relevant to the intended crop.
9. Using These Resources Outside the UK
The microbial research resources in this directory provide useful international background. UK digestate certification resources have a specific geographical scope.
PAS 110 and BCS certification should not be treated as international approvals. Producers and buyers elsewhere should establish the national or regional requirements for microbial fertilisers, organic fertilisers, soil improvers and waste-derived materials.
Local crop trials, suitable quality assurance and practical affordability remain important when assessing a product.
10. Frequently Asked Questions About Biofertilizers
What are examples of biofertilizers?
Common microbial examples include Rhizobium and related rhizobia, Azotobacter, Azospirillum, phosphate-solubilising microorganisms and mycorrhizal fungi. Some formulations combine several organisms in a microbial consortium.
What is the difference between biofertilizer and organic fertilizer?
A microbial biofertiliser uses living microorganisms to support nutrient availability or uptake. An organic fertiliser supplies nutrients from organic-derived materials. Some products combine these functions, but the terms are not interchangeable.
Is anaerobic digestate a biofertiliser?
In the UK anaerobic digestion sector, biofertiliser is used in a certification context for qualifying digestate. Digestate supplies nutrients and organic material and is different from a formulated microbial inoculant.
Is compost a microbial biofertiliser?
Compost is an organic soil amendment that can contribute nutrients. It should not automatically be equated with a preparation containing selected beneficial microorganisms.
Can biofertilisers replace manufactured fertilisers?
There is no universal replacement rate. Digestate can contribute measurable nutrients, while microbial inoculants work through biological functions. The contribution depends on the product, crop, soil and management conditions.
Does PAS 110 alone establish that digestate can be used without waste controls?
Do not rely on PAS 110 alone. Check current BCS Scheme Rules, the relevant national end-of-waste framework and the conditions applying to the material’s supply and use.
Where can I find digestate nutrient values?
AHDB’s RB209 Section 2 provides reference information. For a particular application, obtain analytical results representative of the supplied digestate where available and use them within the nutrient plan.
11. Where to Start
For microbial biofertiliser definitions and examples, begin with FAO and ICAR. For UK digestate nutrient planning, start with AHDB’s RB209. For certification, sampling and national end-of-waste requirements, consult the Biofertiliser Certification Scheme.
For further explanations, read our digestate introduction and agricultural application guide.
Resource list reviewed in October 2026. Consult the linked organisations for subsequent revisions. This article provides background information; use current official requirements and site-specific advice for operational decisions.
You omitted I think to mention one very important UK political change last year when Defra, Parliament & WRAP all began at last singing from the same hymmsheet? The well-known Waste Hierarchy now correctly shows AD above Composting, which some of us have been lobbying for a long time rightly so. Studies have shown that AD is actually slightly more financially & economically better also, a fact often misunderstood by local authorities who now should be digesting organic waste rather than composting it! Ideally, local authority & private plants should combine both on the same location.
Thanks for pointing out the change to the Waste Hierarchy which I had not been aware of.
I also agree wholeheartedly with your statement: “local authorities who now should be digesting organic waste rather than composting it”. Strangely, our local food waste collection goes into our garden-waste wheelie, which is composted. That’s done, I presume, simply to save the council money?
Are you advocating that garden waste should go to anaerobic digestion as well as food waste? In principle I would agree for everything non-woody, and yet wouldn’t that be more expensive (in gate fee charges) than composting, and therefore an impossible thing to ask for in view of further impending LA funding cuts?
Thanks for prompt response. The probable reason your foodwaste goes with garden waste to composting (same as our local council!) is down to (a) longterm waste collection contracts, (b) council customary practice based on believing it’s the cheapest (not so!) and unfamiliarity with AD and change process involved (with cutback shortages), (c) Waste hierarchy previously placed composting above AD? Our community group have just met with our council (9 months after receiving our ‘free’ detailed study proposal for beneficial switching of all their foodwaste & market agricultural waste from composting to AD to save them cost & CO2. The change in policy was also raised & they are in the process of appraising new longterm collection contract with major UK consultant. (Kind of David & Goliath situation for us!)
Some garden & municipal waste will be OK for AD, (and even Indians have used AD for lignin feedstock, but maybe dry rather than wet process?). That’s why I was suggesting ideally councils should have combined plant to optimise process for all feedstock collected. In our area in 2011, a county council residual bin composition survey found 26% was foodwaste which goes to either EfW or RDF (destroying the potential fertiliser!) & pays an extra £62/Te gate fee over composting!! Furthermore, average foodwaste caddy setout rate for our council (only one of 10 statutorily requiring source segregation!) is only 35% (worse in urban locations)! Commercial foodwaste is much worse with probably most going as residual to EfW or RDF (& some maybe to landfill?). Virtually all UK councils are the same I suggest, and continuing failure of government to legislate policy requirement for all commercial foodwaste source segregation, and pre-process in waste stations by producers that recover all resource for subsequent collection and AD (i.e. polluter pays!) is appalling economic loss (& environmental pollution!). Our study has also identified significant opportunities for further savings in the process of collection & processing. But, who is listening?
Good post. I am being taught something challenging on totally different webs everyday. Looks like it’s time to consider getting into this. Thanks for sharing.
I came across your “Biofertilizer Resource List – It’s a Must-Have!” with web page. I found it useful but can I ask you a question. You say excessive nitrogen loss to the environment. I heard that ammonia emissions were a problem for biogas digestion.