hen reading up on what soil your plants need, you have probably come across the impossible phrase ‘moist but well-drained’ and puzzled over what that could possibly mean. The soil all gardeners want is loam, which has a mineral fraction of about 10-20 per cent clay, with the rest consisting of roughly equal amounts of sand and silt. The other major component of soil is organic matter, some of which is added to soils directly by plants, both from chemical exudates from roots and from the death of roots themselves. Dead organic matter also arrives at the
