Soil and Additives

6 Functional Group Guide for Soil - Microbiological components of a soil bioassay.
http://www.bbclabs.com/english/sixfg_soil_guide.html

Gardening Information: Soil - Collection of articles from Oregon State University on various aspects of soil: use of amendments and cover crops, temperature, acidity, moisture, and testing.
http://extension.oregonstate.edu/news/category_search.php?searchCat=soil

The World of Soil - An introduction to soil components, acidity, fertility, and care, as well as a collection of links to other soil resources.
http://soil.hostweb.org.uk/

Do It Yourself.com: Fertilizer, Compost, and Soil - Series of projects, articles, and tips on fertilizing, composting, and nutrient management.
http://www.doityourself.com/scat/fertilizercompostsoi

Improving Soil - Oregon horticulturalist offers information on soil components, pH, testing methods, and nutrients, and means of improving it by using amendments and improving drainage and aeration.
http://www.rodsgarden.50megs.com/improvingsoil.htm

The Schundler Company - Collection of articles and resources about the horticultural uses of perlite and vermiculite.
http://www.schundler.com/hort.htm

Colorado PlanTalk: Iron Chlorosis - Explains how iron deficiency affects trees and plants, with links to more detailed information.
http://www.ext.colostate.edu/ptlk/2115.html

Vermiculite.com - One-page site giving suggestions on where to purchase vermiculite in the United States, along with some uses and properties of vermiculite.
http://www.vermiculite.com