The following important features are new to the eighth edition: over 60 full-color, captioned photos highlighting soil and plant features, including world rainfall and world evapotranspiration; a new introductory chapter providing historical perspective and a discussion of the use of computers by soil scientists; expanded coverage of environmental problems as related to agriculture; discussion of the technology of Geophysical Information Systems (GIS) and Global Positioning Systems (GPS); exploration of the concepts and methods of Precision (variable rate) Agriculture; a new chapter on Greenhouse Soils and Soilless Culture; vital information concerning wetlands; listing of the AASHTO (highway) and Unified engineering soil classification systems; and tabulation and comparison of the Food and Agriculture Division of the United Nations (FAO) with the U.S. map.