It annually recycles a million tonnes of sludge from English and Welsh human sewage, it takes thousands of years to develop, but can be destroyed in minutes, and one gram of it contains a billion bacteria, 95 per cent of which have yet to be identified. Soil, the Hidden Resource is a poster for secondary schools that’s full of facts about what it describes as “the fragile living skin of our planet”. A coloured map shows the distribution of 30 soil types, while issues relating to pollution, biodiversity and intensive agriculture are clearly explained. The poster can be ordered from Helen Taylor, The Environment Agency, Rio House, Waterside Drive, Aztec West, Bristol BS324UD, or downloaded from www.mistral-pr.co.ukNSRIImages

TOM DEVESON