Epigeic earthworm species may feed directly on microorganisms or litter material and inhabit the organic layer of soil. They have been shown to strongly affect decomposition processes (Sampedro et al., 2008) and modify the fungal composition of forest soils (McLean et al., 2000). Generally, effects of earthworms on microbial biomass and activity depend on soil conditions (Shaw et al., 1986; Wolters et al., 1992).
Aira et al. (2006) showed that microbial biomass and activity in pig slurry were significantly decreased by transit through the gut of the epigeic species
Eudrilus eugeniae. It appears that
E. eugeniae is able to digest microorganisms present in pig slurry (Aira et al., 2006). The effects of earthworms on microorganisms depend on the kind of food source and availability and the species of earthworms involved (Flegel et al., 2000; Tiunov et al., 2000). McLean et al. (2006) found that invasive earthworms decreased microbial biomass in surface soils with a high organic carbon content and increased microbial biomass in the underlying mineral soils. Zhang et al. (2000) found that large numbers of the anecic earthworm
Metaphire guillelmi decreased microbial biomass C, N and P after 24 h, thereby concluding that earthworms used microorganisms as a secondary food source.
An attempt to distinguish between nutrient-enrichment processes associated with the OM incorporation and gut-associated processes associated with the passage of soil and OM through the gut of
Lumbricus terrestris was made by Devliegher et al. (1997). They concluded that nutrient-enrichment processes but not gut associated processes were responsible for the increased microbial biomass and activity reported in the presence of
L. terrestris. Meanwhile, endogeic earthworms can transport fresh organic detritus from the soil surface into burrows while mixing it with mineral soil. In the case of tropical endogeic species, it has been demonstrated that the addition of water and readily assimilable intestinal mucus to the ingested soil rapidly stimulates microbial activity. In the second half of the earthworm gut, the mucus will have been almost entirely metabolized and the microorganisms start to degrade the SOM into assimilable OM. This form of OM is then used by both the worms and the microorganisms. Furthermore, the interactions between earthworms and microorganisms occur at several spatial scales in the drilosphere (Brown et al., 2004). The drilosphere concept (
Figure 1) was developed by Bouché (1972), originally to describe the 2-mm-thick zone around the earthworm burrow walls. Lavelle (1997) completed the meaning of drilosphere by including earthworm communities, the digestive tract content, and all microbial and invertebrate populations. Up to 60% of the C losses from earthworms during their life span can be in the form of mucus secretion, and this soluble organic carbon is an important microbial stimulant in the drilosphere (Brown et al., 2004).
Just a small bit that I have been studying .
- mate, that BBAK is going to tip the scales nicely! And all chunky nugg's too - 
... root ball is amazing as expected!
nooooohhh not Mr. Leek! ...Flower that bugger out - 
On a happier note plant is doing just fine [ Day 45 ] If you have a close look you will see a twin branch growing , Like it when this happens 
