| Building Fertile Soil | | Guide to creating and maintaining good quality soil, emphasizing organic materials and composting, from the Center for Agroecology and Sustainable Food Systems. |
| 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. |
| Improve Your Garden Soil | | Covers a wide range of garden soil topics, including soil types, pH, nutrients, testing, composting and fertilizers. |
| 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. |
| Iron Chlorosis | | Explains how iron deficiency affects trees and plants, and how to correct it. Ohio State University fact sheet. |
| Lead Contamination In The Garden | | Covers causes and effects of elevated lead levels, recommends both health and soil screening procedures, and provides guidelines for gardening in areas with lead contamination. |
| The Schundler Company | | Collection of articles and resources about the horticultural uses of perlite and vermiculite. |
| The World of Soil | | An introduction to soil components, acidity, fertility, and care, as well as an extensive collection of links to other soil resources. |
| Vermiculite.com | | One-page site giving suggestions on where to purchase vermiculite in the United States, along with some uses and properties of vermiculite. |
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