Fries-Groning concept is weapon against nitrogen problem

What happens when you add magnesium salt to slurry? Then you get a manure that enriches the soil, making crops like grains and grasses grow better. That's how it started years ago for Andries Huisman of Gorredijk. He founded his company FarMin in response to the discovery and has since helped many farmers improve the quality of manure.

But: there appeared to be many more benefits to the invention. Benefits that have more far-reaching consequences than soil quality. The treatment with magnesium salt turns out to be an effective means of combating nitrogen emissions. And then there are also environmental benefits because significantly less fertilizer is needed. Huisman: "Farmers essentially make their own fertilizer this way, but without any adverse substances.

For magnesium salt producer Nedmag of Veendam, which has been FarMin's salt supplier since the very beginning, this makes the technology even more interesting. Because helping to solve the nitrogen problem together is something the Groningen company is interested in. And so testing with different doses, techniques and treatments is now underway on a large scale.

Ammonia becomes struvite

So using salt to reduce the nitrogen problem. That sounds unreal. Yet this apparent wizardry is simply described in many a chemistry book. The magnesium molecules trap the ammonia molecules, as it were. Together they form the crystal struvite. Such a crystal is less volatile and remains in the soil. The magnesium molecules important for crops remain available longer. And it saves quite a bit of emissions.

Andries Huisman discovered this extremely positive side effect of his manure improver by sticking his nose into a cow barn. It smelled a lot less penetrating than elsewhere, where his salt had not yet been mixed with the manure. Better yields and fewer emissions. The first tests at "pot level" showed that with the right ratio of manure-salt an emission reduction of no less than forty percent could be achieved.

This requires further development and larger-scale research. This is also happening, at the Dairy Campus in Leeuwarden in particular. There are two test barns there. They are identical. Same conditions, similar cows in them. By 'enriching' the manure in one barn with magnesium salt and not in the other, the benefits can be measured exactly.

Film layer

Huisman worked with several parties to build an automated dosing system for its salt, so that quantities can easily be adjusted according to conditions. Anko Vos is closely involved in the project on behalf of Nedmag. 'We are on the right track, but also discovered that 'in real life' is different from the lab scale after all. You have to deal with more variables, which forced us to adjust the process.'

Initially, the salt was mixed directly into the manure pit. That yielded remarkably little result. So Huisman, Vos and the researchers at the Dairy Campus made some adjustments. Anko Vos: "Fresh manure contains the most ammonia, then it dissipates quickly. That fresh layer falls on top of the manure pit every day, so we knew: that's where we need to be, at that top layer.' It was right. Since the magnesium salt is misted over the fresh manure like a film layer, results have skyrocketed.

I discovered this extremely positive side effect of my manure improver by sticking my nose into the cow barn. It smelled a lot less penetrating than elsewhere, where the salt had not yet been mixed into the manure.
Andries Huisman, FarMin