17 soil biodiversity and agriculture
Table 3. The expected impact of the three earthworm ecotypes on key biological processes in agricultural systems.18 Earthworm ecotype
Biological process
Epigeic
Endogeic
Anecic
Aggregation at the soil surface
high
low
high
Aggregation within the soil profile
low
high
low
Formation of biopores
low
high
high
Decomposition - surface residues
high
low
high
Decomposition - subsurface residues
low
high
low
Carbon sequestration
low
high
low
Nutrient mineralisation
high
high
high
Nutrient loss
low
low
high
Microbial activity
high
high
high
Primary production
low
high
high
100m
1 hectare 100m
10,000 m2
3000 kg
x60
Soil may contain a living biomass of earthworms in the order of 3000 kg per hectare - the equivalent of six cows or 60 sheep. It is possible for one square meter of soil to be home to up to 1000 earthworms.