The drilosphere is the part of the
soil
Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...
influenced by
earthworm
An earthworm is a soil-dwelling terrestrial invertebrate that belongs to the phylum Annelida. The term is the common name for the largest members of the class (or subclass, depending on the author) Oligochaeta. In classical systems, they we ...
secretions, burrowing and castings. Therefore, it is the fraction of soil which has gone through the digestive tract of earthworms, or the lining of an earthworm burrow. The average thickness of the drilosphere (lining of an earthworm burrow) is 2mm, but it can be much wider (about 8mm) around the burrows of litter-feeding earthworms.
Through the drilosphere, earthworms influence soil microbial communities, with effects on microbial processes related to
soil organic matter
Soil organic matter (SOM) is the organic matter component of soil, consisting of plant and animal detritus at various stages of decomposition, cells and tissues of soil microbes, and substances that soil microbes synthesize. SOM provides numerou ...
and nutrient dynamics.
[Earthworm Ecology
By Clive Arthur Edwards. 2nd Ed. 2004. CRC Press. ] A study of one soil type found that contained within the drilosphere was 40 per cent of the
aerobic (and 13 per cent of
anaerobic)
nitrogen-fixing bacteria and 16 per cent of the
denitrifiers.
[T. Bhatnagar, Lombriciens et humification: Un aspect nouveau de l'incorporation microbienne d'azote induite par les vers de terre.] The drilosphere is generally richer in nitrogen, phosphorus, and humified organic material than the surrounding soil. This is probably because earthworms preferentially ingest plant residue such as leaf and root litter, or occasionally fungi.
The term was coined by
M. B. Bouché.
References
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Soil