Living in this very top layer of fluffy, crumbly, moist soil mixed with leaf material and humus, are the animals that begin the process of humification.  Many of these primary decomposers are larger, insect-like animals commonly known to gardeners, including the wood lice that we call pill bugs because they roll up defensively into hard armadillo-like shells, and the highly intrusive earwigs my daughter calls pinch bugs.  There are also numerous types of insect larvae busily at work.

A person could spend their entire life trying to understand the ecology of a single handful of humus-rich topsoil.  For a century now, numerous soil biologists have been doing just that and still the job is not finished.  Since gardeners, much less ordinary people, are rarely interested in observing and naming the tiny animals of the soil, especially are we disinterested in those who do no damage to our crops, soil animals are usually delineated only by Latin scientific names.  The variations with which soil animals live, eat, digest, reproduce, attack, and defend themselves fills whole sections of academic science libraries.

During the writing of this book I became quite immersed in this subject and read far more deeply into soil biology and microbiology than I thought I ever would.  Even though this area of knowledge has amused me, I doubt it will entertain most of you.  If it does, I recommend that you first consult specialist source materials listed in the bibliography for an introduction to a huge universe of literature.

I will not make you yawn by mentioning long, unfamiliar Latin names.  I will not astonish you with descriptions of complex reproductive methods and beautiful survival strategies.  Gardeners do not really need this information.  But managing the earth so that soil animals are helped and not destroyed is essential to good gardening.  And there are a few qualities of soil animals that are found in almost all of them.  If we are aware of the general characteristics of soil animals we can evaluate our composting and gardening practices by their effect on these minuscule creatures.

Compared to the atmosphere, soil is a place where temperature fluctuations are small and slow.  Consequently, soil animals are generally intolerant to sudden temperature changes and may not function well over a very wide range.  That’s why leaving bare earth exposed to the hot summer sun often retards plant growth and why many thoughtful gardeners either put down a thin mulch in summer or try to rapidly establish a cooling leaf canopy to shade raised beds.  Except for a few microorganisms, soil animals breathe oxygen just like other living things and so are dependent on an adequate air supply.  Where soil is airless due to compaction, poor drainage, or large proportions of very fine clay, soil animals are few in number.