these book recommendations come from Tom Morris, Associate Professor, Soil Fertility;  Coordinator, Professional Development Program, Northeast Region, USDA Sustainable Agriculture Research and Education Program (SARE); Department of Plant Science at the University of Connecticut.
1.Building soils for better crops, Fred Magdoff and Harold van Es. 2nd edition, 2000, Sustainable Agriculture Network (SAN). Cost was $19.95 plus shipping. Book is being revised and is temporarily out of print. The 3rd edition should be available soon. Check this website for availability. This is an excellent guide to soils. The authors are from Vermont (Magdoff) and New York (van Es).
2. Nature and Properties of Soils, (14th Edition) (Hardcover) by Nyle C. Brady and Ray R. Weil. This is the “bible” for people interested in soils. It is expensive: $102.70 at Amazon. Used copies can sometimes be found at Amazon at a reduced price. This book has had numerous updates in past 10 years. If you can find the 12th or 13th edition at a discount, it would be worthwhile buying because there is not much difference between editions – some fancier graphics in later editions. Amazon link