Podzol

Podzol, one of the 30 soil groups in the classification system of the Food and Agriculture Organization (FAO). Podzols form under forested landscapes on coarse parent material that is high in quartz. They have a characteristic subsurface layer known as the spodic horizon made up of accumulated humus and metal oxides, usually iron and aluminum. Above the spodic horizon there is often a bleached-out layer from which clay and iron oxides have been leached, leaving a layer of coarse-textured material containing primary minerals and little organic matter. Podzols usually defy cultivation because of their acidity and climatic environment. Occupying almost 4 percent of the total continental land area on Earth, they range from Scandinavia to Russia and Canada in the Northern Hemisphere, to The Guianas near the Equator, to Australia and Indonesia in the Southern Hemisphere. Podzols are closely similar to the Spodosol order of the U.S. Soil Taxonomy. Albeluvisols are a related FAO soil group also exhibiting a bleached-out layer.