Look

When we ask you to look for the soil animals, the obvious difficulty is they are hard to see. Look at DIY on how to extract them from the soil

There are in the UK an estimated 12 quadriilion (estimated as couldn't be counted!) small soil animals, according to Countryside Survey (2007) p167. While lots of people are looking into space and asking whether life exists out there, most people haven't a clue just how many specs of life exist under our feet. A quadrillion is a thousand trillions, and most people couldn't name one of them. Let's have an overview of the key soil characters

We are going to look at them from the Top to Bottom, on the way looking at the small soil creatures and how they interact with each other and other parts of the soil.

Then we'll have a look at the state of UK soils, in relation to these mesofauna see UK Soil Survey.  There is a lot of talk nowadays about 'Soil Health' and what is meant by that. We're going to try and determine soil animal indicators of good soil health - look at Soil Health Indicators


Smell

I am often asked 'What is that lovely smell of soil following rain after long dry period?'  The answer is that it is a chemical called
'geosmin'. This chemical - Dimethyl-9-decalol, is produced by filamentous bacteria called Streptomyces common in the soil. They look like fungi and produce spores. When under stress, (eg drought) they produce the spores which are much more resistant to adverse conditions. When the rain hits the ground the spores are thrown up to become a soil water aerosol. So we breath the spores containing the chemical for that lovely smell. I have yet to hear of a perfume manufacturer recreating the smell. The bacteria revert to being filamentous when the soil is damp - so no smell. These bacteria are saprophytic - meaning they eat dead stuff.

"Researchers discovered geosmin specifically attracts springtails. Studying the antennae of the springtails the researchers discovered the organisms can directly sense geosmin...The springtails eat the Streptomyces, so the geosmin is attracting them to a valuable food source. And, the springtails distribute the spores, both stuck on their bodies and in their faeces, which are full of viable spores, so the Streptomyces get dispersed. This is analogous to birds eating the fruits of plants. They get food but they also distribute the seeds, which benefits the plants.”