15 November 2017

Nanofertilizers to significantly reduce the discharge of agricultural phosphorus


Agricultural and aquatic environments will benefit from phosphorus abatement through a new collaborative research project that aims to limit fertilization discharge using nanotechnology. Innovation Fund Denmark is investing 14 Million kroner in the project.

Wheat takes on a reddish hue when lacking phosphorus. While essential for plant growth, excessive phosphorus can decimate aquatic environments. (Photo: PLEN

Every year, farmland is over-fertilized with phosphorus. The excess accumulates in soil without benefitting crop production. In fact, only 15-25 percent of phosphorus inputs benefit plant growth.

Furthermore, excess phosphorus gradually destroys aquatic environments. As a result, the Danish government’s new agricultural package requires the agricultural sector to reign in phosphorus discharges significantly.

A new project at the University of Copenhagen’s Department of Plant and Environmental Sciences, supported by Innovation Fund Denmark, seeks to develop a more effective phosphorus fertilizer using nanotechnology. Trying an entirely new approach, researchers are encapsuling phosphorus in biodegradable nanoparticles that plants can absorb directly through their leaves, thus avoiding the binding of phosphorus to soil.

"The project heralds a paradigm shift, where we can use phosphorus precisely when plants need it," says project manager Søren Husted, plant sciences professor at the Department of Plant and Environmental Sciences.

Husted expects nanofertilizers to be able to reduce current agricultural phosphorus use by 25-30 percent.

Nanofertilizers also make it easier to limit fertilization to times in the growing cycle when crops are able to exploit phosphorous.

"The goal is to replace the 25 kilograms per hectare of phosphorus currently used on an annual basis, with between 5-8 kg of phosphorus that will enter plants directly. In doing so, we will be able to bypass the soil altogether and the mechanisms that bind fertilizer in a form that is useless to plants. The enormous quantity of phosphorus used today will never be absorbed by plants and is a colossal waste of a precious and limited natural resource. It also poses an environmental problem as phosphorous inevitably leaches into aquatic environments," says Husted.

Effective nanophosphorus is a win-win

Besides environmental gains, the precision use of phosphorus will greatly reduce the cost of expensive fertilizers and potentially lead to greater crop yields.

Leif Knudsen, Senior Consultant for fertilizers at SEGES, a project partner, explains that, "It is truly a ‘win-win’ if we succeed in optimizing phosphorus uptake in crops. It is of financial benefit for farmers and of great benefit to the environment."

The other project partner, Flex Fertilizers, will produce the fertilizer and ensure that nanofertilizers are able to compete economically with traditional fertilizers.

"We must demonstrate that the new phosphorus fertilizer is more effective than current fertilizers. Because the fertilizer will be more expensive, we must be able to justify the price premium. If there is an economic incentive, the doors will open for those farmers who might not necessarily have the means to afford the price increase," says product manager Allan Holm Nielsen.