HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by López-Ulloa, M. Articles by de Koning, G. H. J. Search for Related Content PubMed Articles by López-Ulloa, M. Articles by de Koning, G. H. J. GeoRef GeoRef Citation Agricola Articles by López-Ulloa, M. Articles by de Koning, G. H. J. Related Collections Tropical Soils Soil Organic Matter Soil Conservation Tropical Soil Management Soil Mineralogy

Soil & Water Management & Conservation

Soil Carbon Stabilization in Converted Tropical Pastures and Forests Depends on Soil Type

^a Georg-August Univ., Institute of Soil Science and Forest Nutrition, Buesgenweg 2, 37077 Goettingen, Germany
^b German Technical Cooperation (GTZ), Ecuador Casilla 17-07-8721, Quito, Ecuador

^* Corresponding author (bioteam1{at}uio.telconet.net)

The influence of soil C stabilization mechanisms is normally not considered in studies on the effects of land use changes. Instead, observed changes are typically explained by differences in litter input. As a result, it is not well known if and how quickly newly incorporated C is stabilized in soils. Our goals were to find out how much soil C was stabilized in two different soil orders (Andisols and Inceptisols) and which are the responsible mechanisms of C stabilization. Furthermore, we looked for evidence that newly incorporated soil C was stabilized in these contrasting soil orders. We selected 25 sites in northwestern Ecuador with two paired plots per site: one plot where pasture was converted to secondary forest and one plot where forest was converted to pasture. In all the plots, soil C content, stocks, and stable isotope (¹³C) signal were measured in the surface soil. The ¹³C values were used to estimate the stocks of soil C derived from forest (Cdf) and from pasture (Cdp) in all plots. We calculated correlations between these stocks and soil and environmental characteristics to identify mechanisms of soil C stabilization. Our results show that long-term stabilization in Andisols was through formation of metal–humus complexes and allophane, while in Inceptisols long-term stabilization was through sorption to clay minerals. We found evidence that recently incorporated C was not stabilized in Andisols, while in Inceptisols, poorly crystalline (hydr-) oxides seemed to have stabilized part of this soil C. We conclude that unless soil C stabilizing mechanisms are explicitly considered, we will not be able to predict the direction and magnitude of changes in soil C stocks following land use changes in the tropics.

Abbreviations: ¹³C, stable isotope • Al_o, aluminium extracted by acid oxalate • Al_p, aluminium extracted by pyrophosphate • Cdf, carbon derived from forest • Cdp, carbon derived from pasture • C_p, carbon extracted by pyrophosphate • Fe_o, iron extracted by acid oxalate • Fe_p, iron extracted by pyrophosphate • LF, light fraction • masl, meters above sea level • Si_o, silica extracted by acid oxalate

This article has been cited by other articles:

				E. A. Paul, S. J. Morris, R. T. Conant, and A. F. Plante Does the Acid Hydrolysis-Incubation Method Measure Meaningful Soil Organic Carbon Pools? Soil Sci. Soc. Am. J., April 19, 2006; 70(3): 1023 - 1035. [Abstract] [Full Text] [PDF]