Soil genesis and classification

a r t i c l e i n f o Keywords: Pedology Soil genesis Soil history Soil taxonomy Soil science in the USA The formation and classification of soils have been a key area of research in the soil science discipline. Major breakthroughs have been brought about since the mid 1800s and it has evolved from conceptual frameworks, to descriptive studies to more quantitative approaches. Some 50 years ago the American soil scientists Stan Buol and Francis Hole hatched idea for the book Soil Genesis and Classification. Now six editions of the book have been published and it has become a standard text book in teaching soil science and pedology in the USA. Over 50,000 copies have been sold and this paper reviews how the book evolved over time, and relates the text to trends and developments in soil formation and soil classification. The formation and classification of soils have been a key area of research since the soil science discipline emerged in the 19th century. Most things beneath the feet of scientists in that time were largely unknown and there were wild speculations on the origin of many soil features. For example, there were theories that stones developed in soils by chemical precipitation and that peat was formed by algae. Initial soil studies in the 19th century focused on geology and parent material on one hand, and agricultural chemistry on the other hand. The chemical school of thought had several followers (Baxter, 1832; Lawes et al., 1883; Ruffin, 1832) but was led by J. von Liebig who was one of the most influential scientists of his time (Blume, 2002; Brock, 1997). An early example that viewed soils from a geological point of view was by J. Morton (1843). Morton discusses alluvial and diluvial soils — a distinction made between fine sediments deposited by water (alluvium), and coarse sediments deposited by floods (diluvium). That geological distinction had a religious origin, and for Morton soils and geology were one. Also Fallou (1862) distinguished between soils formed in-situ and " washed-in " or alluvial soils and as he was trained as a mineralogist he attributed variations in soils primarily to differences in soil forming rocks. Senft (1857) and Fallou (1862) prepared the way for V.V. Dokuchaev (Blume, 2002) who brought the study of soils out of the chaos and confusion of the geo-logic, chemical, and agronomic points of view and established …