Destabilization of soil during the production of earthworm (Lumbricidae) and artificial casts

R. P. Hindell, B. M. McKenzie, J. M. Tisdall

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

The mechanisms by which soil is destabilized in the digestive tract of endogeic earthworms were investigated with artificial casts, which were moulded with a syringe from slurries of a silty loam with or without gypsum and organic matter treatments, and compared to casts produced by Aporrectodea rosea (Lumbricidae). Both types of casts generally had the same levels of mechanical dispersion, observations of slaking, and particle size distribution when the casts were fresh, aged-moist for 30 days, or air-dried. Fresh casts were significantly more dispersive than the uningested soil despite the addition of gypsum or organic matter to the soil. However, the dispersion from aged-moist or air-dried casts was not substantially greater than that of uningested soil. Air-drying was more effective than moist-ageing in increasing the stability of casts and uningested soil. The concentration of soluble carbohydrate was greater in artificial casts produced froth soil treated with sheep dung or xanthan gum, and in earthworm casts produced from soil treated with xanthan, than in the uningested soil of the same treatments. An increase in the concentration of soluble carbohydrate was related to an increase in dispersion. An attempt was made to simulate the addition of mucus to soil in the digestive tract of earthworms, by the addition of sucrose or xanthan gum to the slurry during the production of artificial casts. The addition of xanthan, but not sucrose, to the slurry increased mechanical dispersion relative to that of the uningested soil in the fresh treatment. Although the production of artificial casts destabilized soil to the same degree as earthworm casts, the artificial casts did not simulate all chemical, biochemical, and microbiological aspects of digestion.

Original languageEnglish
Pages (from-to)153-163
Number of pages11
JournalBiology and Fertility of Soils
Volume24
Issue number2
DOIs
Publication statusPublished - Feb 1997

Keywords

  • Aporrectodea rosea
  • Artificial cast
  • Carbohydrates
  • Dispersion
  • Earthworm cast

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