[Gasification] Forest Duff & Earthworms - Off Topic ?

[Jeff Davis]

Kind of off topic:


Aren't earthworms good for soil and gardens?

It depends. Earthworms create a soil of a certain consistency. For soils 
that are compacted due to heavy use by agriculture and urbanization, for 
example, earthworm tunnels can create "macro-pores" to aid the movement 
of water through the soil. They also help incorporate organic matter 
into the mineral soil to make more nutrients available to plants. 
However, in agricultural settings earthworms can also have harmful 
effects. For instance, their castings (worm excrement) can increase 
erosion along irrigation ditches. In the urban setting, earthworm 
burrows can cause lumpy lawns.

Relative to simplified ecosystems such as agricultural and 
urban/suburban soils, earthworm-free hardwood forests in Minnesota have 
a naturally loose soil with a thick duff layer. Most of our native 
hardwood forest tree seedlings, wildflowers, and ferns grow best in 
these conditions. However, when earthworms invade they actually increase 
the compaction of hardwood forest soils. Compaction decreases water 
infiltration. Less infiltration combined with the removal of the duff 
and fallen tree leaves results in increased surface runoff and erosion.

<http://www.dnr.state.mn.us/invasives/terrestrialanimals/earthworms/index.html>



Jeff