China was sorting its soils into nine classes by the 5th century BCE
The oldest known soil classification appears in the Chinese text Yu Gong from the 5th century BCE, sorting land into three categories and nine classes by colour, texture and water. Yet the idea that soil is a living body with its own history, rather than crumbled rock, only took hold in the 19th century.
Two contemporaries share credit for founding the modern discipline: Friedrich Albert Fallou in Germany and Vasily Dokuchaev in Russia. Fallou came first, studying soil origins before Dokuchaev was even born, but Dokuchaev's broader work proved more influential. Before them, soil was treated as a lifeless product of rock chemistry, essentially the same thing as bedrock. Dokuchaev argued instead that soil is a natural body with its own genesis, shaped by climate, vegetation, relief and age, and changed by water, air and organisms. In 1959 Nikiforoff captured the modern view by calling soil the excited skin of the Earth's crust.
The field has two classic branches. Pedology studies soil in its natural setting; edaphology studies it in relation to the uses that depend on it. Both draw on physics, chemistry and biology, and contributors range from engineers and archaeologists to microbiologists and planners. Many key concepts even came from outsiders such as biologists and philosophers.
Classification has gone global. In 1998 the World Reference Base for Soil Resources replaced the FAO scheme as the international standard, and its fourth edition dates from 2022. Unlike USDA soil taxonomy, it leaves climate out except where climate shows up in the soil profile. Folk systems persist too, most familiarly the split between heavy clay soils and light sandy ones. Light soils are easier to work and resist trampling cattle, but they erode more readily, and despite the names they need not weigh less.
Mapping remains a core task: almost every part of the United States has a published soil survey, and digital methods now use remote sensing. Newer research focuses on climate change and storing carbon in soil. Linking soil quality to farming has drawn critics, among them Norman Borlaug, father of the Green Revolution, and Pedro Sanchez, both advocates of biotechnology for tropical hunger. Paradoxically, the rise of offshoot disciplines contributed to falling investment in soil science teaching and research around 2000.
Source: Soil science
