Nitrogen deposition (mostly through fossil fuel combustion and high-intensity agriculture) causes a higher acidity of the soils which inhibits decomposition. Also, chemical changes occur which reduce the availability of phosphorus for the soil fauna such as microarthropods. Liming appears to have even a reinforcing effect on phosphorus availability, because phosphorus is then bound to calcium, a compound of the lime. Therefore, new restoration projects focus on rock dust as a replacement. Ideally, nitrogen deposition will be reduced soon. If there is sufficient loam in the soil, it still recovers, as does the soil fauna. ► Contact: Henk Siepel
, Radboud University Nijmegen, The Netherlands.