TY - JOUR
T1 - Organic carbon accumulation on soil mineral surfaces in paddy soils derived from tidal wetlands
AU - Wissing, Livia
AU - Kölbl, Angelika
AU - Schad, Peter
AU - Bräuer, Tino
AU - Cao, Zhi Hong
AU - Kögel-Knabner, Ingrid
N1 - Funding Information:
The authors thank Rui Yin and the Institute of Soil Science, Chinese Academy of Sciences, in Nanjing for support during sampling at the chronosequence site around Cixi and for logistic handling. We thank especially Reinhold Jahn and Vanessa Vogelsang for providing us with inorganic carbon data and Pieter Grootes for determination of the radiocarbon content. Markus Steffens is acknowledged for assisting with statistical analysis and Werner Häusler for the support concerning the soil mineralogy measurements. We thank Monika Heilmeier for technical assistance and Martina Bauer, Carolin Botond, Robert U. Hagemann, Tahereh Javaheri, Juliane Teichmann and Maria Vonach for student research assistance. We are grateful to the Deutsche Forschungsgemeinschaft (DFG) for their generous funding of Research Unit FOR 995 “Biogeochemistry of paddy soil evolution.” The authors also thank the two anonymous reviewers for their helpful comments which greatly improved the manuscript.
PY - 2014/9
Y1 - 2014/9
N2 - We studied organic carbon (OC) accumulation in organo-mineral associations during soil development on calcareous parent material. Two chronosequences in the Zhejiang Province, PR China, were investigated; one under paddy cultivation with a maximum soil age of 2000years, and the other under upland crops where the oldest soil was 700years old. Bulk soils and soil fractions of the uppermost A horizons were analyzed for OC concentrations, radiocarbon (14C) contents, total pedogenic iron oxide concentration and oxalate extractable proportions of iron (FeOX) oxides. The specific surface area of soil minerals was measured with the Brunauer-Emmett-Teller (BET-N2) method on four conditions: untreated, after organic matter removal, after iron oxide removal and after removal of both. Initial soil formation on calcareous marine sediments includes soil decalcification and OC accumulation. Paddy soils are characterized by an accelerated decalcification, higher contents of OC and FeOX oxides, and a pronounced accumulation of modern OC. The mineral constitution of the soil material indicated already a certain degree of weathering since the earliest stages of pedogenesis and remained unchanged in paddy and non-paddy soils. The study provides no evidence of formation of new clay-sized minerals during soil development, which could supply new surfaces for OC accumulation. However, the study revealed higher OC coverage on mineral surfaces in decalcified paddy soils. Therefore, we assume the specific surface area and the specific affinity of FeOX oxides for OC storage to play an important role for OC accumulation in organo-mineral associations. In contrast, the surface area of minerals in non-paddy soils, in which decalcification and the proportion of FeOX oxides were much lower, showed significantly lower OC coverage. Selective removal of SOM or iron oxides clearly showed that iron oxides and SOM protect each other in organo-mineral associations primarily in paddy fine clay-sized fraction. Thus, we explained the higher OC coverage on mineral surfaces by complex association between clay minerals, iron oxides and SOM in paddy soils.
AB - We studied organic carbon (OC) accumulation in organo-mineral associations during soil development on calcareous parent material. Two chronosequences in the Zhejiang Province, PR China, were investigated; one under paddy cultivation with a maximum soil age of 2000years, and the other under upland crops where the oldest soil was 700years old. Bulk soils and soil fractions of the uppermost A horizons were analyzed for OC concentrations, radiocarbon (14C) contents, total pedogenic iron oxide concentration and oxalate extractable proportions of iron (FeOX) oxides. The specific surface area of soil minerals was measured with the Brunauer-Emmett-Teller (BET-N2) method on four conditions: untreated, after organic matter removal, after iron oxide removal and after removal of both. Initial soil formation on calcareous marine sediments includes soil decalcification and OC accumulation. Paddy soils are characterized by an accelerated decalcification, higher contents of OC and FeOX oxides, and a pronounced accumulation of modern OC. The mineral constitution of the soil material indicated already a certain degree of weathering since the earliest stages of pedogenesis and remained unchanged in paddy and non-paddy soils. The study provides no evidence of formation of new clay-sized minerals during soil development, which could supply new surfaces for OC accumulation. However, the study revealed higher OC coverage on mineral surfaces in decalcified paddy soils. Therefore, we assume the specific surface area and the specific affinity of FeOX oxides for OC storage to play an important role for OC accumulation in organo-mineral associations. In contrast, the surface area of minerals in non-paddy soils, in which decalcification and the proportion of FeOX oxides were much lower, showed significantly lower OC coverage. Selective removal of SOM or iron oxides clearly showed that iron oxides and SOM protect each other in organo-mineral associations primarily in paddy fine clay-sized fraction. Thus, we explained the higher OC coverage on mineral surfaces by complex association between clay minerals, iron oxides and SOM in paddy soils.
KW - Chronosequence
KW - Decalcification
KW - Iron oxides
KW - Paddy rice cultivation
KW - Pedogenesis
KW - Specific surface area
UR - http://www.scopus.com/inward/record.url?scp=84899942873&partnerID=8YFLogxK
U2 - 10.1016/j.geoderma.2013.12.012
DO - 10.1016/j.geoderma.2013.12.012
M3 - Article
AN - SCOPUS:84899942873
SN - 0016-7061
VL - 228-229
SP - 90
EP - 103
JO - Geoderma
JF - Geoderma
ER -