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| Titel |
Carbon sequestration in maize and grass dominant cropping systems in Flanders |
| VerfasserIn |
Philippe Van De Vreken, Anne Gobin, Roel Merckx |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250093391
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| Publikation (Nr.) |
 EGU/EGU2014-8065.pdf |
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| Zusammenfassung |
| Sources of soil organic matter (SOM) input to the soil in agro-ecosystems are typically crop
residues. The question arises how removing crop residues from a field influences soil
carbon sequestration. We investigated four long-term maize and grass dominant
cropping systems each with a different residue management. Under silage maize (SM)
all stover is removed from the field and only a stubble remains, whereas under
grain maize (GM) only the grains are harvested and all stover is returned to the
soil. Fields with a history of at least 15 consecutive years of either SM (with or
without a second annual crop of Italian ryegrass) or GM, and fields under permanent
grass were selected from a geodatabase that covers 15 years of crop rotation for all
of the ca. 500,000 agricultural fields in Flanders. For each cropping system 10
fields were sampled (40 in total) following the area-frame randomized soil sampling
(AFRSS) protocol (Stolbovoy et al., 2007). For 6 out of 10 fields only the topsoil was
sampled (0-30 cm), whereas for the 4 other fields both topsoil and subsoil (30-60 cm
and 60-90 cm) were sampled. The total soil organic carbon (SOC) and nitrogen
content and the stable carbon isotope ratio (13C/12C) were determined for each soil
sample. From each field 1 topsoil sample was fractionated by the Zimmermann
fractionation procedure (Zimmermann et al., 2007) which distinguishes between 5
different SOC fractions (POM, DOC, silt and clay associated SOC, chemically
resistant SOC, SOC associated with sand fraction). Besides analysis of the SOC and
nitrogen content of each fraction, the origin of the carbon was determined through
isotope-ratio mass spectrometry. Although there was no significant difference between
SM and GM regarding the total SOC stock for the upper 30 cm (ca. 75 à 80 Mg
C.ha-1), fields under continuous GM contained in the 0-30 cm layer 60% more
maize-derived C4-SOC as compared to fields under continuous SM (ca. 14 and 9
Mg C.ha-1 respectively). Significant differences could also be demonstrated for
the carbon fractions of soils with different cropping histories. Each fraction of a
GM-topsoil contained significantly more C4-SOC as compared to a SM-topsoil (with or
without a second annual crop) with the sizes of the fractions being equal. The more
labile POM- en DOC-fractions accounted for the biggest part of the maize C4-SOC
detected in the bulk sample, whereas the silt and clay associated SOC and chemically
resistant SOC consisted mainly out of old grass C3-SOC. For the deeper soil layers no
significant differences could be demonstrated between GM and SM, neither for the total
SOC stock nor for the C4-SOC stock. Our results suggest that the soils with maize
cropping systems in Flanders are near carbon saturation, such that crop residue
management does not influence the total amount, but rather the quality of the carbon
sequestered.
Stolbovoy, V., Montanarella, L., Filippi, N., Jones, A., Gallego, J., and Grassi, G. (2007).
Soil sampling protocol to certify the changes of organic carbon stock in mineral soil of the
European Union. Version 2. EUR 21576 EN/2. Office for Official Publications of the
European Communities, Luxembourg. 56p.
Zimmermann, M., Leifeld, J., Schmidt, M.W.I., Smith, P., and Fuhrer, J. (2007).
Measured soil organic matter fractions can be related to pools in the RothC model. European
Journal of Soil Science, 58: 658-667. |
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