NatureToday | Do the grasses increase the nitrogen problem in nature?

Grazers in nature do not disturb the balance

Meta Rijks, senior ecology advisor at Staatsbosbeheer: “No, grazers do not increase the nitrogen problem in nature. Nitrogen is a nutrient traditionally found in nature and plays an important role there. The problem first arose when a lot of extra nitrogen was released into the air and into the groundwater. This nitrogen accumulates in nature, causing some plants – the nitrogen-loving plants – to multiply and create roughness. Other plants don’t stand a chance. This leads to a one-sided vegetation with major consequences for biodiversity. We use grazers in some nature reserves, partly because they eat the nitrogen-loving plants. So they eat the nitrogen-rich vegetation first. With their faeces and urine, that nitrogen is returned to nature. The total nitrogen remains about the same; the balance will not be disturbed further.”

Difference with cows in the meadow

Rijks: “If cows only feed on grass from their unfertilized pastures, the balance would not be further disturbed. But this is almost never the case. This whey is normally fertilized, with manure from, for example, the bio industry and artificial fertilizers. The extra nitrogen from this ends up in both the animal and the environment. The other difference is that the cows receive additional feed that does not come from the same area. It often does not even come from the Netherlands. Also, not all the protein in the concentrate is absorbed by the cows. This ends up in the manure and urine. When spread on land, the nitrogen from the urine evaporates in the form of ammonia. The ammonia ends up in other areas through the air. The fertilizer and urine also immediately release more nitrogen to the soil than the soil can process, so it ends up in the groundwater. And via the groundwater also in nature reserves.”

Benefit of grazers

Although grazers in the wild do not provide more nitrogen in a nature reserve, it only slightly reduces it. Rijks: “Their advantage is primarily that they prevent nitrogen-loving plants from multiplying too much. They keep the vegetation open so that plants that are lower and grow less quickly still get enough light. The smaller plants also benefit from the places that grazers create with their kicking open legs or horns: these are good places for germination. Nevertheless, the grasses also help to limit the supply of nitrogen. For example, if animals walk in a deep litter barn at night – which is often the case with sheep – they leave a large part of their This means that you also extract nitrogen from nature. But the manure from the deep litter barn must of course be processed properly. On a smaller scale, for example, grazing horses and donkeys create manure sites in nature. This actually helps to store nitrogen , impoverishment of the grazing areas and to concentrate on the manure site, which contributes to the variation in the terrain which is counteracted in agriculture.”

Urine and feces

And what about the consequences of urine and feces? Rijks: “In livestock farming, you see that urine and faeces often collect in animals that are kept in stables. Thanks to a chemical reaction, more ammonia is formed. Ammonia is a gas that evaporates, precipitates elsewhere and still ends up in the soil. In animals in the wild, this ammonia is produced much less. Firstly, because they consume less protein and secondly, because the urine and faeces end up in different places. Ammonia in natural soil is particularly harmful. There it produces acids that loosen essential ‘buffer substances’ from the soil and cause them to be washed into deeper soil layers. There, the buffer substances become out of reach for plants and fungi, which means that many species of, for example, lean sandy soil have a very difficult time. And die out.”

Mowing versus grazing

In addition to grazing, mowing is of course also a good way to keep the vegetation open. Rijks: “The advantage of mowing is that you can remove the clippings. This removes the nitrogen stored in plants from the area. This is sometimes useful, especially if a lot of nitrogen has accumulated, such as in soils, that has been fertilized until recently But mowing and disposal also comes at a price: it requires access to heavy machinery that can damage the soil and also release (a little) nitrogen An ecological disadvantage is that you don’t just mow the nitrogen-loving plants , but all vegetation, including plants you want to leave it right After mowing it is very bare for a while The advantage of grazing is that the animals are present for months They cause, due to their behavior, a great variation in the plants height and causes small bald spots. This in turn is favorable for small animals. That’s why we choose to graze some areas and mow others. It’s tailored.”

More information

  • Read more about how grazers help with nature management.

Text and photos: Staatsbosbeheer
Photo: Twan Teunissen (main photo: Galloway beef)

Leave a Comment