Farmers have probably always realised that soil is alive. Good soil seems to have certain intangible qualities, over and above its physical structure and chemistry. There is something special about topsoil. What are these intangible qualities? We all know that microorganisms in the soil can cause disease. However, in the last 25 years scientists have started to recognise the importance of some very helpful soil inhabitants, especially the vesicular arbuscular mycorrhizal (VAM) fungi and beneficial bacteria.