Martin Leue (ZALF Müncheberg,
Germany), Ruth Ellerbrock & Horst Gerke
"Local-scale distribution of organic matter composition and wettability at surfaces of preferential flow paths"
Surfaces of preferential flow paths in
structured soils consist of clay-organic coatings on soil aggregates or
linings on biopores. The outermost layer of such surfaces is mostly covered
by organic matter which finally controls wettability and sorption properties
that are relevant for transport along the flow path. The objective of this
study is to compare the local 2D distribution of soil OM composition at
intact aggregate and biopore surfaces with that of the wettability. Intact
surfaces of aggregated soil samples were scanned using a DRIFT mapping
procedure. Wettability was observed by means of contact angle measurements.
In contrast to the uncoated surface areas, organic coatings on worm burrows
and root channels show relatively higher CH/CO-ratios that correspond with
longer water drop infiltration. Both, the OM composition of coatings along
preferential flow path surfaces and the water repellence are spatially
variable at this local scale.