alfisol

Alfisols are one of the twelve soil orders recognized by the World Reference Base for Soil Resources (WRB) and the United States Department of Agriculture’s (USDA) Soil Taxonomy system. These soils are characterized by the presence of an argillic horizon, which is a layer enriched with clay that has been translocated from above by the process of eluviation and illuviation. Alfisols typically form under forest vegetation in regions with moderate to high precipitation, though they can also develop under grasslands or savannas.

The name "Alfisol" is derived from the Latin word *albus*, meaning "white," referring to the lighter-colored eluvial (E) horizon often found above the argillic horizon. These soils generally have a higher base saturation (greater than 50%) in the argillic horizon, indicating a relatively high content of exchangeable calcium, magnesium, potassium, and sodium. This property makes Alfisols fertile and suitable for agriculture, particularly for growing crops like wheat, corn, and soybeans.

Alfisols are commonly found in temperate and subtropical regions, including parts of North America, Europe, Asia, and South America. They often develop on upland landscapes with well-drained conditions, though some may occur in lowland areas. The clay accumulation in the argillic horizon contributes to their structural stability, reducing erosion risk while retaining moisture for plant growth. However, their fertility can decline if subjected to intensive cultivation without proper management, such as the addition of organic matter or liming to maintain pH levels.

These soils play a crucial role in ecosystems by supporting diverse plant and animal life. Their moderate fertility and drainage make them valuable for both natural and agricultural systems, though their productivity can vary depending on climate, parent material, and land-use practices. Alfisols are classified into various subtypes based on specific characteristics, such as texture, depth of the argillic horizon, and presence of other diagnostic features.