Swiss Federal Research Station for Agroecology and Agriculture, Zurich-Reckenholz

The earthworm populations in two soils

The relation between earthworm populations and site properties was studied in a gleyic and in a calcaric cambisol. In the wet gleyic cambisol the earthworm biomass was 54 % higher than in the drier calcaric cambisol. By increasing the aeration of the soil and a more intense mixing of organic and mineral soil constituents, earthworms generally enhance the activity of soil micro-organisms. On the other hand both groups of organisms are feeding on dead soil organic matter, thereby competing with each other. A strong reproductive and intensive nutrient mineralizing activity of earthworm populations may therefore – depending on the site conditions – reduce the development of microbial biomass in soil. In order to understand nutrient cycling in soil, population dynamics and metabolic activity of earthworms have to be considered.

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