Transformation of the soil structure through Pontoscolex corethrurus (Oligochaeta) intestinal tract

Interactive effects of functionally different earthworm species on aggregation and incorporation and decomposition of newly added residue carbon

“…In the present study, residue-derived C concentrations within microaggregates in large macroaggregates (or residue-derived intra-POM C) were higher in the presence of earthworms than when no earthworms were present when residue was incorporated in the soil. This has been reported before by several researchers (Shipitalo and Protz, 1988;Mulongoy and Bedoret, 1989;Daniel and Anderson, 1992;Barois et al, 1993;Buck et al, 1999;Bossuyt et al, 2004). On the other hand, residue-derived C concentrations between microaggregates in large macroaggregates (or residue-derived inter-POM C) were lower in the presence of earthworms than when no earthworms were present.…”

“…Barois et al (1993) found that the soil microstructure was completely destroyed in the earthworm's gut and that during gut transit old microaggregates were destroyed and new ones formed. Our results showed that most microaggregates were present in small macroaggregates when earthworms were absent while most microaggregates were located in large macroaggregates in the presence of earthworms and when residue was incorporated in the soil.…”

Chemical and physical properties of earthworm casts as compared to bulk soil under a range of different land-use systems in Vietnam

“…After the soil is ingested by earthworms, it undergoes many transformations in the gut. Interparticle bonds are initially disrupted by ingestion and afterwards strengthened due to thixotrophic hardening and bonding of clay with incorporated organic debris (Lee and Foster, 1991;Shipitalo and Protz, 1988;Barois et al, 1993. This modification of soil microstructure led to the decrease of soil porosity, as observed with bulk density and image analysis.…”

Formation Mechanisms of Humic Substances in the Environment

“…In general, litter that contains high amounts of carbohydrates and N -containing biomolecules is preferentially ingested, while litter containing large amounts of lignin polyphenols and tannins is avoided; thus, this can lead to an enrichment of recalcitrant biomolecules (Wolters, 2000 ). Ingested soil, organic residues, and stabilizing compounds are thoroughly mixed in invertebrate digestive tracts; this can lead to the exposure of lignocellulose to microfl ora in the gut (Hammel, 1997 ), as well as to the formation of stable organomineral complexes (Barois et al, 1993 ). In general, soil fauna are not able to digest lignin, cellulose, and other large highly aliphatic or aromatic compounds.…”