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Searching the critical soil organic carbon threshold for satisfactory tilth conditions – test of the Dexter clay:carbon hypothesis

Schjønning, P.; de Jonge, L.W.; Moldrup, P.; Christensen, B.T. and Olesen, J.E. (2010) Searching the critical soil organic carbon threshold for satisfactory tilth conditions – test of the Dexter clay:carbon hypothesis. [På jagt efter et nedre, kritisk indhold af organisk stof i jord - test af Dexter's ler:kulstof hypotese.] In: de Jonge, L.W.; Moldrup, P. and Vendelboe, A.L. (Eds.) Proceedings of the 1st international conference and exploratory workshop on soil architecture and physico-chemical functions "Cesar", Aarhus University, Faculty of Agricultural Sciences, Research Centre Foulum, Tjele, Denmark, pp. 341-346.

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Summary

The concern for deteriorating soil structure at low soil organic matter (SOM) contents calls for better knowledge of SOM interaction with soil minerals as well as guidelines for soil conservation. We measured clay dispersibility in a field with a textural gradient. Our results support the concept of differentiating soil content of clay in a complexed and non-complexed part although our data did not point out an exact clay/OC ratio threshold. Our results also indicated that labile fractions of SOM may play an important role in soil physical behavior. We revisited literature data and found evidence that soil content of fines (<2 or <20 μm) is a major determinant of soil specific surface area (SA). We noted that soil SA coverage with SOM changed dramatically at a specific ratio of either clay (<2 μm) or clay+silt (<20 μm) with soil OC. This is an indirect support of the recently suggested quantification of the soil mineral ‘saturation’ hypothesis. More studies are needed on the causal relationships. We conclude that clay/OC~10 or (clay+silt20μm)/OC~20 are corresponding indices reflecting shift in soil physical behavior.


EPrint Type:Conference paper, poster, etc.
Type of presentation:Paper
Subjects:"Organics" in general
Crop husbandry > Production systems
Soil > Soil quality
Crop husbandry > Crop combinations and interactions
Farming Systems
Crop husbandry > Composting and manuring
Environmental aspects > Biodiversity and ecosystem services
Research affiliation: Denmark > DARCOF III (2005-2010) > CROPSYS - The effect of cropping systems on production and the environment
Denmark > AU - Aarhus University > AU, DJF - Faculty of Agricultural Sciences
ISBN:87-91949-59-9
Deposited By: Schjønning, Senior Soil Scientist Per
ID Code:18441
Deposited On:18 Mar 2011 11:51
Last Modified:18 Mar 2011 11:51
Document Language:English
Status:Published
Refereed:Not peer-reviewed

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