The purpose of this publication is to summarize the recent knowledge regarding the formation and significance of the great soil groups in the United States for the general reader. The treatment is in no sense complete or exhaustive. Attention is directed toward a discussion of those principles in broad implication. Should the reader require more specificity, the detailed reports of surveys and researches must be consulted.

This publication is the fourth in a series designed to aid in the recognition and identification of pathological conditions of economic importance affecting fruits and vegetables in the channels of marketing, to facilitate the market inspection of these food products, and to prevent losses from such conditions.

Soils are affected by human activities, such as industrial, municipal and agriculture, that often result in soil degradation and loss. In order to prevent soil degradation and to rehabilitate the potentials of degraded soils, reliable soil data are the most important prerequisites for the design of appropriate land-use systems and soil management practices as well as for a better understanding of the environment. The availability of reliable information on soil morphology and other characteristics obtained through examination and description of the soil in the field is essential, and the use of a common language is of prime importance. These guidelines, based on the latest internationally accepted systems and classifications, provide a complete procedure for soil description and for collecting field data. To help beginners, some explanatory notes are included as well as keys based on simple test and observations.--Publisher's description.