@article{LeueGerkeGodow2015,
  author    = {Leue, Martin and Gerke, Horst H. and Godow, Sophie C.},
  title     = {Droplet infiltration and organic matter composition of intact crack and biopore surfaces from clay-illuvial horizons},
  series = {Journal of plant nutrition and soil science = Zeitschrift f{\"u}r Pflanzenern{\"a}hrung und Bodenkunde},
  volume    = {178},
  journal   = {Journal of plant nutrition and soil science = Zeitschrift f{\"u}r Pflanzenern{\"a}hrung und Bodenkunde},
  number    = {2},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1436-8730},
  doi       = {10.1002/jpln.201400209},
  pages     = {250 -- 260},
  year      = {2015},
  abstract  = {The organic matter (OM) in biopore walls and aggregate coatings may be important for sorption of reactive solutes and water as well as for solute mass exchange between the soil matrix and the preferential flow (PF) domains in structured soil. Structural surfaces are coated by illuvial clay-organic material and by OM of different origin, e.g., earthworm casts and root residues. The objectives were to verify the effect of OM on wettability and infiltration of intact structural surfaces in clay-illuvial horizons (Bt) of Luvisols and to investigate the relevance of the mm-scale distribution of OM composition on the water and solute transfer. Intact aggregate surfaces and biopore walls were prepared from Bt horizons of Luvisols developed from Loess and glacial till. The mm-scale spatial distribution of OM composition was scanned using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The ratio between alkyl and carboxyl functional groups in OM was used as potential wettability index (PWI) of the OM. The infiltration dynamics of water and ethanol droplets were determined measuring contact angles (CA) and water drop penetration times (WDPT). At intact surfaces of earthworm burrows and coated cracks of the Loess-Bt, the potential wettability of the OM was significantly reduced compared to the uncoated matrix. These data corresponded to increased WDPT, indicating a mm-scaled sub-critical water repellency. The relation was highly linear for earthworm burrows and crack coatings from the Loess-Bt with WDPT >2.5 s. Other surfaces of the Loess-Bt and most surfaces of the till-derived Bt were not found to be repellent. At these surfaces, no relations between the potential wettability of the OM and the actual wettability of the surface were found. The results suggest that water absorption at intact surface structures, i.e., mass exchange between PF paths and soil matrix, can be locally affected by a mm-scale OM distribution if OM is of increased content and is enriched in alkyl functional groups. For such surfaces, the relation between potential and actual wettability provides the possibility to evaluate the mm-scale spatial distribution of wettability and sorption and mass exchange from DRIFT spectroscopic scanning.},
  language  = {en}
}
@article{vanSchaikPalmKlausetal.2014,
  author    = {van Schaik, Loes and Palm, Juliane and Klaus, Julian and Zehe, Erwin and Schroeder, Boris},
  title     = {Linking spatial earthworm distribution to macropore numbers and hydrological effectiveness},
  series = {Ecohydrology : ecosystems, land and water process interactions, ecohydrogeomorphology},
  volume    = {7},
  journal   = {Ecohydrology : ecosystems, land and water process interactions, ecohydrogeomorphology},
  number    = {2},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {1936-0584},
  doi       = {10.1002/eco.1358},
  pages     = {401 -- 408},
  year      = {2014},
  abstract  = {Due to its high spatial and temporal variability, preferential flow is difficult to measure and quantify. Earthworms create macropores that provide common pathways for preferential flow. Therefore in this article, we link earthworm abundance to macropore numbers and hydrological effectiveness, with the future aim to use species distribution models of earthworms for the spatial parameterization of preferential flow. Earthworms are generally categorized into three ecological types with varying burrowing behaviour, resulting in a different impact on soil hydrological processes. Therefore, we studied the relationships between the abundance of the earthworm ecological types and macropores of different size classes and in different soil depths. The abundance and biomass of earthworms were well correlated to different sizes of macropores in different soil depths. This is mainly the case for the larger, vertically oriented macropores (>6mm diameter), which are generally connected to the soil surface and hydrologically most effective. The correlation of total earthworm biomass and macropores ranges from 072 to 089 for different soil depths. Although there is quite some variation in infiltration patterns, infiltration from macropores into the matrix is profile-specific, as it varies strongly between profiles, but not within one profile. Macropore coating seems to have a larger effect on this macropore matrix interaction than the soil physical properties of the matrix. Although the amount of macropores and their effectiveness are clearly related to the earthworm distribution, the variation in infiltration from macropores to soil matrix should be further studied.},
  language  = {en}
}