“If you let cows eat less protein, there will be less nitrogen in their manure.”

Within three years, 40 dairy farmers were able to reduce ammonia emissions on their farms by an average of 20 percent. This was done through a limited number of measures, including modifying the feed.

“We can go even deeper in this area,” says Gerard Meijschels of Wageningen University and Research, who coordinates the network of practice projects. The aim is to reduce emissions of ammonia, as well as the greenhouse gas methane, by 30 percent by 2025. The project should serve as an example for the rest of the Netherlands’ approximately 14,000 dairy farmers.

The pressure on the agricultural sector to reduce nitrogen emissions is great. Many of these are located in legally protected nature reserves (Natura 2000), causing many of these areas to deteriorate when they should be improving. Agriculture has the largest share of so-called nitrogen deposition, nearly 50 percentIn agriculture, dairy farms contribute a lot to this deposition, especially in the form of ammonia (NH3).₃). To improve the status of Natura 2000 areas, ammonia emissions must be cut by at least half, according to Michels. The question is: how?

The new government, led by BBB, is focusing primarily on innovation. It was no coincidence that Agriculture Minister Femke Wiersma made her first working visit this month to a dairy farmer who had installed a rain system in his barn.

“We are also testing two of these systems in our project,” says Mijschels in an office, sipping a cup of coffee. “It makes the stable floors cleaner, which means less ammonia is released. The water seeps into the manure cellar and dilutes the manure, which also releases less ammonia.” But in his project, he first started working on fodder with the 40 farmers.

Why food first?

“What doesn’t go in doesn’t come out. The amount of nitrogen in the feed is reflected in the manure, including in the stable and in the field. Feed is the key. Also, adjusting the feed saves the farmer costs, because it means he uses less fertiliser and concentrates. This is in line with the new government’s less money for nitrogen policy.

Each gram reduction means approximately a 1 percent reduction in emissions, whether in the stable or in the field.

How do you get less nitrogen in your feed?

“By reducing the protein content, because proteins are rich in nitrogen.”

Is this level too high now?

“It’s generally too high. Farmers and feed consultants like to offer too much. It works as a kind of insurance premium. The idea is: if the quality of the harvested forage is not good, it will still have enough protein and the quality and milk production will be maintained. We help farmers keep the insurance premium as low as possible, because there is room for that. It requires more of your craftsmanship. So we see a lot of variation between farmers. The goal is to get them closer to 150 grams of protein per kilo of dry matter of forage. There are some who have already reached 145, but others are still over 170.

How can you reduce the protein content in feed?

“For example, a farmer can fertilize his grass with less nitrogen. Or he can wait before mowing. Young grass has a lot of protein, while older grass has less. You can also add more corn to the ration, because it has a relatively low amount of protein.

Does this modification of protein content have an effect?

“In three years, farmers were able to reduce the amount of protein per kilo of feed by an average of 9 grams. Each gram reduction means about a 1% reduction in emissions, both in the stable and in the field. The reduction in emissions from stables can be attributed mainly to the adjustment of feed. In the field, emissions were reduced even more. We also see that farmers fertilize less, partly because Brussels is gradually removing the exemption granted to the Netherlands.

“The difference between farmers is huge. There are those who are very active. But we also have farmers who are very critical, who wonder if the hype around nitrogen is exaggerated. In that sense, we have a reflection of reality, and I am happy about that. The dairy farmer who is participating in the plug scheme has already stopped. There will be a stop next year without a successor. And a few others are converting to organic.

The wisdom is: If the laundry hanging outside dries quickly, there is no point in spreading the dung.

How do you know exactly how much those emissions have been reduced?

Many dairy farmers in the Netherlands work with KringloopWijzera kind of food accounting for each company. What kind of feed does the farmer use, what kind of soil does he grow in, what breed of cows does he raise, how much fertilizer and liquid manure is used? You can calculate emissions based on that. The database is also constantly expanding.

“In addition, our project includes fourteen companies that we have equipped with sensors to measure ammonia and methane, among other things.”

What other measures are there to reduce ammonia emissions?

“There are many. For example, watering the barn. Or letting the cows out to pasture more. Moreover, the farmer can take the weather into account more when spreading manure. The best is no wind, and fairly cool weather. It is preferable to do this in the morning when there is dew. The wisdom is: if the laundry dries outside quickly, there is no point in spreading the manure.”

There was a lot of resistance at first, but it has already diminished.

How can you get all this knowledge to the other 14,000 dairy farmers in the Netherlands quickly enough?

“We’re now looking at this in our project as well. We’re following 60 other dairy farmers who are being advised by feed consultants, vets and accountants. We’re looking at how this advice works, why farmers do or don’t do something. And what do we need to organise to remove resistance? There was a lot of resistance at first, but it’s really diminished. We hardly talk about why reducing emissions is important for the environment or the climate. Then it becomes an easy task. We’re really talking about practical things.”

Can you solve the nitrogen problem this way? So without having to reduce the herd?

“The challenge is very big in and around nature reserves. Other WUR researchers say it makes sense to follow three paths: purchase, expansion around nature reserves, and measures like the ones we are studying in our project. I think that is true.

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