Ensuring food waste doesn’t go to waste

That is what Yara is trying to address along with Veolia in a groundbreaking project that has the potential to transform how farmers feed their crops while also utilizing food waste that would otherwise end up in landfill.

Yara has joined forces with Veolia, the transnational waste management group, to look at how to recycle nutrients from urban, agricultural and industrial waste into high-quality fertilizers. The initiative aims to demonstrate how a circular economy vision for food can be achieved at scale.

Yara is providing the nutritional expertise in this circular economy alliance, while the technical challenge for providing the product itself falls on Veolia.

London has been chosen as the city that will address the technical challenges and explore the opportunities for turning its estimated two million tonnes of food waste into this novel green fertilizer. UK farmers are the first to try it out.

What are the benefits for the farmer? The immediate benefits are a potential increase in soil health and, as a market develops for it, carbon credits.

“There are clear benefits in terms of organic matter it can bring, but for us the challenge is its nutrient value –– there’s a fine balance to be struck between a straight organic matter addition and a classic mineral fertilizer,” says Mark Tucker, Marketing and Agronomy Manager, Yara Europe.

Utilizing organic and mineral nutrients

The product in this project is quite different from organic matter currently spread on farm, such as sewage sludges or composts. It’s known as organo-mineral fertilizer (OMF), which contains inorganic fertilizers and organic materials of biological origin formulated to utilize nutrients of both organic and mineral origin. OMF fertilizers have a high dry matter – around 80-90%. This also concentrates any nutrient content, but relative to mineral components, they remain a relatively small fraction of the material that’s in a pelleted or granular form. OMF can be enriched or coated with mineral ingredients to boost its nutrient content.

“There’s work needed to understand the nutrient content and guaranteeing the consistency of this,” says Andrew Weeks, who manages Veolia’s organic waste recycling to agriculture.

“Climate change and soil erosion have moved up on the agenda and that's led to a sea change in how waste materials are viewed.”

Andrew Weeks, General Manager, Veolia Environmental Services UK

What exactly is the potential for agriculture? Dr. Ruben Sakrabani, a senior lecturer in soil chemistry at Cranfield University, has spent many years researching OMF and its value for agriculture.

According to Ruben, OMF brings discernible differences in soil quality, increasing moisture retention and soil organic matter content. “The difficulty with the material is in its production. To bring it from 25% dry matter up to the 85-90% needed for efficient transport and effective spreading requires a lot of heat. There may be opportunities to use waste heat, depending on the nature of the plant processing it, but clearly if you need to use fossil fuels to produce OMF that would cancel out its green credentials,” he says.

Ruben believes this is one of the main barriers, despite the obvious benefits for soil health and the circular economy. However, there could be even greater benefits in terms of carbon capture. “There’s a lot of talk at present of carbon capture technologies. But this is static carbon –– what may be of more interest is to influence the active carbon in soils with OMF,” he explains.

While Mark says we still need to acquire a lot of knowledge before we can strike the right balance between a straight organic matter addition and a classic mineral fertilizer, he adds:

“There's a change in mindset taking place - it's not just about crop performance any longer but what you can do for your soil to optimize its performance. I think the solutions lie in a combination of organic additions and carefully selected nutrients. ”

Mark Tucker, Marketing and Agronomy Manager, Yara Europe

Yara is examining other cities where this pilot project can be duplicated. Ultimately, we seek to make the circular food model commercially viable at scale: turning urban food waste into organic fertilizers that can be sold to and used by farmers in and around cities around the world.