Soil Orders

develop under forest in humid regions of cool to warm temperatures. They have a thin gray to brown A₁ horizon and a clay-rich A₂ horizon. Alfisols have medium to high base saturation and have an adequate moisture supply most of the year. They are generally fertile agricultural soils.

form from weathering processes that generate minerals with little orderly crystalline structure. The minerals can result in an unusually high water- and nutrient holding ability making them good argricultural soils. They are associated with rocks having volcanic origin.

Soils of arid regions that have one or more diagnostic horizons. They have low organic-matter content and a light-colored surface layer. Salts may accumulate at or near the surface. They are made productive for agriculture by irrigation

soils lacking horizon development. They are found in many parts of the world.

soils that have permafrost near the soil surface and have evidence of freeze-thaw activity

wet, organic soils in which production of plant material exceeds mineralization. Mucks, peats, marls shrink when drained. In warm climates, they are good agricultural soils after drainage.

humid-region soils having at least one distinguishable horizon. They are young in age.

deep-profile soils with high base status and a seasonal moisture deficit. They are associated with grasslands. They have solft, dark-brown to black upper layer. They may have a B horizon of calcium carbonate accumulation. THey are very productive for grain crops.

deeply weathered tropical and subtropical soils low natural fertility. They have low base saturation and limited capacity to hold nutrients against leaching. Hard laterite (plinthit) layers are common. They are generally unsuited for crop agriculture

range from subtropical to very cold conditions. They have a ____ A₂ horizion incorporating active organic matter beneath a light-colored, leached, sandy A₁ horizon. They are generally marginal for agriculutre.

Include a variety of tropical and subtropical soils with a variety of soil-moisture regimes. They have low base status, a subsurface clay horizon and low nutrient-holding ablility. They are very old soils characterized by long weathering of their clay minerals. They are generally marginal for agriculture.

dark tropical and subtropical soils developed on heavy clays. They have shrinkage cracks when dry which become filled with loose surface materails that absorb moisture and swell during wet seasons. They are generally fertile and suited for agriculture

Koeppen climates of Alfisols

Koeppen climates of Spodosols

Koeppen climates of Mollisols

Koeppen climates of Oxisols

Koeppen climates of Ultisols

associated with permafrost, layer beneath surface doesnt't thaw

volcanic parent material, basaltic lavas

refering to plant tissue
***Organic Soils
BW climates often

refers to recent- a youthful soil time, haven't been around long enough to develop distinct horizons

youthful soils, were once andisols, but have 1 distinct layer

Can be found in subtropical to cold regions
soil is deflocculated by hydrogen
generally on sandy parent material
often lack CO₂