Simulating Field-Scale Soil Organic Carbon Dynamics Using EPIC

SSSAJ: Volume 71: Number 4 • July–August 2007 Soil Sci. Soc. Am. J. 71:1174-1185 doi:10.2136/sssaj2006.0356 Received 16 Oct. 2006. *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 balance between primary production, decomposition, and lateral transfers of soil organic matter (SOM) determines the amount of organic C sequestered in soils. The evaluation of complex mechanisms and interactions, by which soil use and management affect the nature and concentration of SOC, is best approached by fi eld experimentation coupled with simulation models. Recent developments in SOC simulation models have led to an integrated understanding of SOC dynamics in the context of SOC sequestration and climate change (Rosenberg et al., 1999). Soil organic matter, containing 50 to 58% C, is a complex mixture of organic compounds with different turnover times (Nelson and Sommers, 1982). There is no simple analytical technique for qualifying and quantifying SOM fractions. In fact, the distinction between some fractions is largely conceptual, and convenient for modeling SOC dynamics. Soil organic C is subdivided into several pools with unique characteristics and decomposition rates. Carbon decay in a compartment is assumed to follow fi rst-order kinetics: