1. Department of Soil Ecology, BITÖK; University of Bayreuth; Dr. Hans-Frisch-Straße 1-3 95440 Bayreuth Germany
2. School of Renewable Natural Resources, Louisiana State University AgCenter; Baton Rouge LA 70803
3. Institute of Soil Science and Forest Nutrition; University of Göttingen; Büsgenweg 2 37077 Göttingen Germany