Soil fauna and the stocking rate of grasslands

If grassland is used too intensively, the diversity of the soil fauna diminishes.

Trends

As the stocking rate rises, the number of soil-dwelling nematodes in the soil under the grass decreases. The number of nematode species declines when the stocking rate exceeds 2 large animal units (see Technical note) per hectare. The species composition also varies: there is an increase in the number of species that are undemanding and break down organic matter less efficiently.

The soil fauna is essential to maintain soil fertility. Nematodes are an important group of soil organisms that decompose the organic matter, thus releasing nutrients for the plants.

The average stocking rate in the Netherlands is decreasing and is currently 1.3 large animal units per hectare. The proportion of farms with a stocking rate of more than 2.5 large animal units per hectare is also decreasing since the 1980s, indicating that the soil fauna can recover. This recovery will probably take a long time, as soil organisms generally travel slowly.

Technical note

The figure shows numbers of nematode species by comparison with the situation with a stocking rate of 1.6 large animal units per hectare (=100%). The latter is roughly the stocking rate on organic livestock farms, which have a well developed soil fauna.

The inventory of the nematodes in the soil is based on research done on 70 livestock farms on sandy soil. The intensity of the grassland use is indicated by the large animal unit per hectare. One such unit is equivalent to an animal that excretes 41 kg phosphate per year. The information on stocking rates is from the CBS-Landbouwtelling.

References

• Boomaerts, J. (2001). Derde Monitoringsrapportage mineralen- en ammoniakbeleid. Expertisecentrum Ministerie van Landbouw, Natuurbeheer en Visserij. Ede.
• Schouten, A.J., J. Bloem, A.M. Breure, W.A.M. Didden, M. van Esbroek, P.C. de Ruiter, M. Rutgers, H. Siepel en H. Velvis (2000). Pilotproject Bodembiologische Indicator voor Life Support Functies van de bodem. RIVM rapport 607604001. Bilthoven.
• Schouten, A.J., A.M. Breure en M. Rutgers (in druk). BoBI op weg: Tussentijdse evaluatie van de Bodembiologische Indicator. RIVM rapport 607604002. Bilthoven.

See also:

Central Bureau for Statistics: theme Nature & Environment