Population density and biomass of earthworms in different types of Egyptian soils.
Earthworms were sampled by hand-sorting at 14 localities in and near the Beheira Province. Soil was analysed for water content, texture, pH, total soluble salts, Cl, HCl-soluble material and organic C. The worms found were Allolobophora caliginosa f. trapezoides and Eisenia rosea f. bimastoides in arable fields and orchards, Pheretima californica and P. elongata in heavy clay garden soil and Gordiodrilus sp in marshy ground. The numbers and average weights of adult A. caliginosa were associated with the water-content/gravel + sand ratio of the soil; this ratio is some measure of the availability of water to the worms. In soils where prevailing conditions were favourable, populations were quite dense. Earthworms were most abundant where soil was least disturbed. Soil pH was not a limiting factor. The scarcity of worms in Egypt results from the dry climate and the fact that most land is arable.