The Intelligent Gardener: Growing Nutrient Dense Food
by Steve Solomon (Author) , Erica Reinheimer (Author)
Publisher: New Society Publishers | Published: December 25, 2012 | ISBN-10: 0865717184 | ISBN-13: 978-0865717183

Reviews of “The Intelligent Gardener: Growing Nutrient Dense Food”
Permaculture Magazine
Good Reads
The Food Garden Group
Gary Kline at Black Lake Organic:

The Nature and Properties of Soils, 14th Edition 
Nyle C. Brady (Author), Ray R. Weil (Author)
Publication Date: September 16, 2007 | ISBN-10: 013227938X | ISBN-13: 978-0132279383 | Edition: 14

Soil Test Analysis Links

OrganiCalc WebApp Notes — “the algorithm”
Manual worksheets from The Intelligent Gardener

Soil survey links

UC Davis:
The USDA classifications are defined here: Soil Classification Definitions

Biochar Links

Biochar activation Delinat Institute Consulting — Vineyards in Biodiversity | Climate Farming biochar by David Yarrow