Closing the loop on nutrient use is becoming a common conversation in the fertilizer sector.

To help meet the future food demands of a growing population, the fertilizer industry is starting to look more seriously at closing the loop on nutrient use.

In terms of sustainable nutrient management, a closed loop or circular system relies on recovering nutrients from the places where they concentrate – livestock operations, wastewater treatment plants and compost facilities, for example – and returning them to food production.

Although some nutrients may still be lost to the environment, a circular system would help to ensure the long-term sustainability and security of food production by both extending the world’s finite supply of nutrients, such as phosphorus (P), and providing the nutrition needed for high-yielding crops.

“Most of the phosphorus for fertilizer comes from non-renewable P rock reserves that will eventually be exhausted,” says Don Flaten, a professor in the Department of Soil Science at the University of Manitoba. Flaten estimates the reserve of P rock will last a couple hundred years, at most, based on current levels of consumption.

However, as food production and fertilizer demand increases, turning to a circular system to recycle nutrients will become increasingly critical to extend the supply. “To get ready for future demands, we need to start recovering and using those nutrients now,” he says.

One of the most abundant sources for these nutrients is right under our noses; or, rather, right under our homes. In cities, the valuable nutrients found in municipal wastewater, including phosphorus, nitrogen and magnesium, are often literally flushed away, breaking the loop.

Although products made with recycled nutrients will not replace traditional fertilizers in the near future, Flaten says it’s a good start. Production of fertilizers from recycled sources will increase, he says, but they will have a long way to go to match the rate of fertilizer production from P rock.

“We’ll never be able to recycle 100 per cent of the P that goes into food production – and we’re not very good at it, yet – so, we’d better start recycling ASAP,” Flaten says. “The general benefit is improved sustainability, which helps society as a whole.”

Seeing Green

Until recently, scaling up nutrient recovery to commercial levels has presented a significant challenge, but Vancouver-based Ostara Nutrient Recovery Technologies Inc. has been making inroads with its Crystal Green fertilizer.

Crystal Green is a phosphorus fertilizer that has been catching the attention of farmers, agronomists and retailers across North America and Europe. The pearlized phosphorus fertilizer contains nutrients recovered at 19 of the company’s “Pearl Reactors,” located in waste treatment plants around the world.

Manitoba retailer Shur-Gro Farm Services Ltd. (Shur-Gro) has been carrying Crystal Green for just over two years and has been happy with the response they’ve received for the product, both from customers and their agronomy staff. Alana Doell, an agronomist at Shur-Gro’s Portage la Prairie, Man. location, says that adding Crystal Green to their product line has made both business and agronomic sense.

“We like to have our producers’ best interests at heart – we want their fields to produce to their highest potential,” says Doell. “We’re always looking for ways to differentiate ourselves from others and be early adopters of innovative products, so that we can offer these to our growers.”

Doell says that Crystal Green is innovative for several reasons beyond its source of nutrients, including better availability in certain soils.

“Crystal Green is more efficient than regular phosphate and it doesn’t get tied up by nutrients like calcium, iron and aluminum, and in high or low pH soils,” she says. “So, when plants have better access to phosphorus and other nutrients, and we have good environmental conditions, we get better yielding crops.”

Another thing that makes Crystal Green different from traditional phosphorus fertilizers is that it must be placed in the seed row because it is insoluble in water and requires the organic acids (citrates) produced by the roots of the young plant to dissolve and release its nutrients. For this reason, it is best to blend it with a traditional, water-soluble fertilizer to get a “pop-up” effect, says Doell.

Although Crystal Green sold out completely in 2019, Doell expects the availability of the product to increase as more reactors come online, including one in Portage la Prairie. She says retailers who are considering selling the product should consider their market and have conversations with their growers about agronomic and economic benefits of the product, along with its sustainability story.

A Sustainable Solution

Sustainability can mean different things to different people, but for Dan Aberhart, managing partner at Aberhart Ag Solutions, it means taking products that are destined for the landfill, recycling them and putting them to good use in an agricultural application.

Aberhart Ag Solutions is the exclusive Saskatchewan and Manitoba distributor for Bio-Sul, a high-volume sulfur fertilizer made from composted food waste, blended with waste elemental sulfur from the oil and gas industry. Although the compost acts primarily as a carrier for the sulfur, Aberhart points out that by using it in Bio-Sul, tens of thousands of pounds of food is kept out of landfills where it would otherwise decompose, creating methane, a potent greenhouse gas.

“We’re literally taking stuff that would normally go into landfill – some of it with the potential to have extreme detrimental effects on the environment – and we’re reconstituting it into nutrients that help grow crops,” says Aberhart. “Something that was at a grocery store that would have gone to a landfill – we’re taking it and we’re putting back into the land. It’s just the coolest thing ever. And I think, going forward, it’s only going to make more and more sense.”

It’s going to be incumbent upon us on so many levels to be using products from the circular economy.
Dan Aberhart

In addition to the sustainability aspect, what makes Bio-Sul unique is that it is applied on a five-year cycle. Because the sulfur particles vary greatly in size, they break down naturally over time – some in the first year and some taking multiple years – providing the crop with sulfur when it is needed, under good growing conditions.

Since his company started selling Bio-Sul in 2015, Aberhart says just over one million acres have been applied. And, due to the five-year cycle of the product, those initial fields will only be receiving their first re-applications this year. Aberhart says it’s an exciting time for the company and he is actively looking for more retailers to carry the product, with the intention that Bio-Sul will go mainstream in the long term.

The success of the product has Aberhart and his team looking at adding other products with a sustainability bent, and he encourages other retailers to consider doing the same, even if it means seeing an increase in competition for his company in the market.

“Agriculture is probably the single biggest opportunity to have a positive environmental impact,” he says. “The sooner you can get on this train, and the more that you can jump in, the better for you. Because this is not a trend that’s going away. It’s going to be incumbent upon us on so many levels to be using products from the circular economy.”