Seed Suppliers
Garden Organic - the national charity for organic growing: (http://www.gardenorganic.org.uk) More than just seeds. Quite expensive for some things though. Member's discount helps.
http://www.tamarorganics.co.uk UK supplier specialising in organic vegetable, flower and herb seeds, fruit, onion sets, seed potatoes and garden products.
Biochar
Video from Dr. Johannes Lehmann of Cornell University, USA, one of the most vocal scientific proponents of biochar's potential.
For balance a sceptical view from Woods End Soil Laboratory, New England, USA
No-Dig
http://www.charlesdowding.co.uk/Homepage Excellent site with no-digging as core philosophy.
http://www.charlesdowding.co.uk/node/66 The dig/no-dig experiment.
Composting
Steve Solomon's wonderful essay Organic Gardener's Composting. All you ever need to know about composting.
Mineralisation
Michael Astera's meandering review of organic theories with a particular focus on his belief that many soils are deficient in minerals.
