Soil structure and characteristics of organic matter in two orchards differing in earthworm activity

摘要: Abstract By consuming plant remains and soil, earthworms incorporate organic matter (OM) into the soil form biogenic structures, which can affect OM dynamics. We carried out a (micro)morphological study of structure development distribution in two orchards (45 year) Dutch calcareous marine loam: RI− without, KR+ with high earthworm activity, result different levels heavy metal contamination from fungicides. In both soils, sedimentary–stratification was absent to 60 cm depth equal amounts calcite spheroids were counted, suggesting similar activity past. current vol.% worm-worked groundmass thin sections 6% Ah 7% Bw horizon compared 51% 16% KR+. Disappearance time gave rise compacted physicogenic angular prismatic aggregates absence biopores. Due restricted fragmentation incorporation fragments casts, litter layer formed at surface. coatings present fissures root pores horizon, indicating mixing mineral materials. relatively coarse (>50 μm) heterogeneously distributed through groundmass. Stronger decalcification than could be ascribed higher production acids homogenisation by earthworms. high, has resulted granular subangular blocky many worm casts Particulate fine (