Livestock farming produces an abundance of valuable nutrients – but when too many nutrients concentrate in one place, they become more of a challenge than a benefit. In areas with intensive animal production, managing excess nitrogen and phosphorus has become a growing concern. Struvite, a mineral slow-release fertiliser recovered directly from manure and digestate, can be a promising solution.
What is struvite?
Struvite (magnesium ammonium phosphate) is a mineral that forms under specific conditions when magnesium, ammonium (nitrogen), and phosphate (phosphorus) are combined. It’s a slow-release fertiliser that helps improve nutrient efficiency while reducing environmental impact.
Why is nutrient overload a problem?
Livestock manure and biogas digestate are rich in essential plant nutrients. However, in regions with high animal density, these nutrients often exceed local crop needs. This leads to:
- Nutrient leaching into groundwater
- Eutrophication of nearby water bodies
- Increased greenhouse gas emissions
- Poor nutrient use efficiency
Balancing nutrient inputs and outputs is key to achieving more sustainable and climate-friendly farming systems.
How is struvite produced?
The steps include:
- Separation of solids from the liquid fraction.
- Acidification to reduce pH and release phosphate.
- Microfiltration to remove particles that inhibit crystal formation.
- Magnesium addition to trigger struvite crystallisation.
- pH adjustment with a base to finalise the precipitation process.
The resulting product is a liquid rich in struvite, which can be further processed into a granulate.
What are the benefits of struvite?
Struvite offers several advantages:
✅ Sustainable phosphorus recycling from organic waste streams
✅ Reduced dependency on finite phosphate rock
✅ Lower risk of nutrient leaching due to its slow-release properties
✅ Transportable form of phosphorus and nitrogen for nutrient rebalancing
✅ Climate-smart alternative to conventional fertilisers
It represents a circular and resource-efficient solution for managing nutrients where they are most concentrated.
Can the remaining manure still be used?
Yes. The struvite recovery process creates two valuable by-products:
- A treated liquid fraction with reduced nutrient content – suitable for spreading with lower environmental risks.
- A thickened solid fraction – ideal for autumn tillage.
Learn more
Watch our new animation below to see how it works. The struvite prototpye was developed within the OG Struvite in Italy. Learn more about Struvite here.
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