News - April 30, 2020

Hoge Veluwe soil gets fertilizer

Roelof Kleis

Sylvana Harmsen has spread thousands of kilos of rock dust in the Veluwe. Over the next few years, cameras will monitor the effect.

In the heart of Hoge Veluwe Park, a woman in a face mask scatters a fine grey powder from a bucket. It is as if she is illegally scattering the ashes of a cherished family member, a joke she has heard many times before. But the powder is actually finely ground rock, which PhD candidate Sylvana Harmsen wants to use to restore the mineral balance in the woodland soil. Nitrogen deposits have severely affected the soil composition.
Rock dust has been proven to work as a soil improver elsewhere in the Veluwe. Harmsen is now looking specifically at its effect on forest rejuvenation. Oaks are having a particularly tough time in the Veluwe. The rock dust comes from a mine in Norway and is rich in potassium, calcium and magnesium. When these minerals are added to the soil, that is good for the growth of young trees.

Eating saplings
But there is a flip side as the saplings also become tastier for grazers such as deer and mouflons. It is unclear whether the negative effect of the grazers offsets the positive effect on rejuvenation. That is where the cameras come in. Harmsen is using Snapshot Hoge Veluwe, an existing network of camera traps, to keep an eye on the grazers. The park has 70 cameras that keep track of grazing intensity. Harmsen is using 12 of these camera traps to track soil enriched with rock dust.

The flip side is that the saplings become tastier for grazers such as deer and mouflons

Incidentally, the fertilization costs a lot of effort. Each trial plot measuring 30 x 30 metres requires Harmsen to scatter 900 kilos, or 180 buckets, of rock dust. Some of the plots have been fenced off to get a picture of the impact of the rock dust without grazers. The project will take five years. Harmsen expects to see the first effects in three years’ time.