Making green organic fertiliser from bones

Sunday, 6 September, 2015
EU-funded researchers have developed a zero-emission method of recycling organic phosphorous fertiliser from animal bones. They aim to help farmers cut down on chemicals – saving them money and making food production safer and greener.

Phosphorous recycling from foodgrade animal bone, ©REFERTIL BIOCHAR

In Europe, the natural cycles of phosphorus and nitrogen have been disrupted by years of intensive farming practices and human activities. Industrial agriculture has often used mineral-based fertilisers to put these compounds back in the soil. The problem is that such fertilisers can contain high levels of cadmium and uranium, which pose a threat to human health.  

As a solution, the EU-funded REFERTIL project, which ends in September 2015, has developed an environmentally friendly industrial-scale method of producing an organic phosphorus fertiliser known as animal bone biochar. Researchers are confident that the resulting end product could be an effective substitute for phosphate mineral fertilisers and chemicals currently used in food crop production.

Biochar originates from different types of plant and animal by-products. It is produced under low temperature conditions in the absence of air; biomass is burned at 600 degrees Celsius in an oxygen-free vacuum with no gases emitted into the atmosphere. The project has successfully achieved zero-emission processing at the industrial scale, where all material element streams are recycled and reused into natural and safe products.

“We have so far been able to scale up the industrial process to produce a throughput of 20 000 tonnes a year,” says project coordinator Edward Someus, a biochar science and technology engineer with Terra Humana, Sweden. “These new REFERTIL-based organic fertilisers will be safe premium products at low and affordable costs. Zero-emission performance biochar production will also not compete with human food, animal feed and plant nutrition production and supply; a new bio-economy will be generated.”

Better for the environment, better for us

Once fully commercialised, bone biochar could help the agriculture sector reduce the use of phosphate and the related carbon footprint. Furthermore, reserves of phosphate rocks used to make such fertilisers are finite, and concerns have been raised that they are in danger of exhaustion.

Someus believes that bone biochar is an effective replacement for phosphate fertiliser. Another advantage of biochar is its micro-porous structures, which can provide a ‘home’ for useful microorganisms in the soil, like beneficial fungi and bacteria. While containing a great deal of phosphate and useful alkaloids such as calcium, biochar is also largely free from any contaminants such as heavy metals, uranium or cadmium, which are often present in rock phosphates. 

Reducing the use of the cadmium and uranium containing phosphate fertilisers will address important health concerns, he adds.

“In Germany, the use of phosphate fertiliser from 1951 to 2011 has resulted in the cumulative application of approximately 14 000 tonnes of uranium on agricultural land, corresponding to an average cumulative loading of 1 kg of uranium per hectare,” says Someus. “The solution is the reduction or even substitution of these mineral fertilisers, such as with natural biochar phosphates.”

A key next step for the project as it nears completion is to disseminate its results to farmers for implementation, policymakers, agricultural suppliers and consumers. For example, the second REFERTIL Spain Regional Workshop and Open Day took place in Toledo on 17 October 2014.

Attendees included representatives from state, regional and local administrations, research centres, recycling and fertiliser companies and representatives from the farming community. The project is confident that biochar phosphorous fertiliser could be on the European market within five years.

REFERTIL Biochar Field Demo Plant in Hungary


Improvement of comprehensive bio-waste transformation and nutrient recovery treatment processes for production of combined natural products
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