i. Alfisols got their name from the chemical symbols al (aluminum) and fe (iron).
ii. They are transitional soils, with more organic matter than ultisols but less than spodosols or mollisols.
iii. Alfisols occupy regions with enough water percolating through the soil to carry small clay particles out of the surface layer.
iv. A subsurface layer of clay accumulation (the argillic horizon) is their necessary diagnostic feature.
v. The rest of the definition of an alfisol is by exclusion.
vi. The soil cannot be so wet, dry, or cold that organic matter accumulates in a histic, mollic, or spodic layer.
vii. The soil also cannot be too highly leached or weathered, so it does not occur in climates that are hot and wet.
viii. Alfisols are, therefore, found mainly in mid-latitude forests and some grass-and-tree savannas.
ix. Most alfisols are fertile and productive; on the average, only mollisols have more agricultural value.