Agriculture Reference
In-Depth Information
3
CHAPTER
Soil Classification: Past and Present
Robert J. Ahrens, Thomas J. Rice, Jr., and Hari Eswaran
CONTENTS
Background and History ..................................................................................................................19
Modern Soil ClassiÝcation...............................................................................................................20
Improvements Needed .....................................................................................................................24
Summary ..........................................................................................................................................24
References ........................................................................................................................................25
BACKGROUND AND HISTORY
Although not recognized as disciplines until the nineteenth century, pedology and soil science
in general have their rudimentary beginnings in attempts to group or classify soils based on
productivity. Early agrarian civilizations must have had some way to communicate differences and
similarities among soils. The earliest documented attempt at a formal classiÝcation of soils seems
to have occurred in China about 40 centuries ago (Lee, 1921). The Chinese system included nine
classes based on productivity. The yellow, soft soils (soils derived from loess) were considered the
best, followed by the rich, red soils. The evidence suggests that the Chinese soil classiÝcation
system was used to levy taxes based on soil productivity (Simonson, 1962).
Cato (234Ï149
), a Roman scientist, contrived a classiÝcation of soils based on farming
utility. His system employed 9 classes and 21 subclasses, and it guided decisions about use and
care of the land for production of food and Ýber (Stremski, 1975). The decline of the Roman Empire
coincided with a general stagnation in the Ýeld of soil science, as noted by the low number of
major contributions in the discipline until the nineteenth century.
The nineteenth century saw renewed interest in studying soil characteristics, in order to relate
tax assessment to soil productivity. In Russia, this effort helped establish the discipline of pedology.
The Russian government in 1882 hired V. V. Dokuchaiev to guide a program that would map and
classify soils as a basis for tax assessment (Simonson, 1962).
Dokuchaiev and his students launched a new era in pedology that promoted the description and
characterization of soils as natural bodies with a degree of natural organization, rather than viewing
soils simply as mantles of weathered rock. This important notion fostered the concept of the pedon,
from which data could be collected and compared. Even after the concept of the pedon took hold
among pedologists to facilitate data collection, soil science still lacked standards to classify soils
BC
19
