TR Y Characteristics of Soil Carbon Buried for 3300 Years in a Bronze Age

SSSAJ: Volume 72: Number 5 • September–October 2008 Soil Sci. Soc. Am. J. 72:1292-1298 doi:10.2136/sssaj2007.0348 Received 25 Sept. 2007. *Corresponding author ([email protected]). © Soil Science Society of America 677 S. Segoe Rd. Madison WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. The turnover and long-term retention of organic matter (OM) in soil is important not only for plant growth but also for the global C cycle (Janzen, 2005). Enhanced sequestration of C in soil may be a measure to alleviate increasing atmospheric CO2 levels, provided that the C is retained in soil OM pools with slow turnover. Radiocarbon dating has shown that OM may indeed persist in the soil for centuries (Falloon and Smith, 2000), but the quantitative signifi cance of the mechanisms responsible for long-term retention of OM in soil remain obscured. Nevertheless, most compartment models for the simulation of OM turnover and storage in soil include a pool of refractory soil OM (RSOM). These pools are taken to include biologically inert OM or OM with extremely slow turnover rates (Christensen, 1996a; Falloon and Smith, 2000). The slow turnover time of RSOM pools excludes direct verifi cation on the time scale of even the longest running fi eld experiment. More than 100,000 burial mounds have been identifi ed in southern Scandinavia and other parts of northern Europe (Kristiansen et al., 2003). Bronze Age mounds were typically constructed entirely from sods that were cut from the area surrounding the burial site and placed upside down (Holst et al., Ingrid K. Thomsen* Dep. of Agroecology and Environment Faculty of Agricultural Sciences Univ. of Aarhus P.O. Box 50 DK-8830 Tjele, Denmark