March, 1998                                          SCSB#391

Juventic - Monosiallitic soil material (<2mm fine earth fraction) with low content of Fe and Al oxyhydroxides, usually < 7% and have more than 10% weatherable minerals in the coarse fraction (>20um).
 

Sesquijuventic - Monosiallitic soil material (<2mm fine earth fraction) with moderate to high content of Fe and Al oxyhydroxides, usually > 7% and have more than 10% weatherable minerals in the coarse fraction (>20um).
 

Sesquimonorthic - Monosiallitic soil material (<2mm fine earth fraction) with moderate to high content of Fe and Al oxyhydroxides, usually > 7% and/or accumulations of more than 5% iron-rich and/or iron cemented bodies such as plinthite. Sesquimonorthic soil materials have less than 10% weatherable minerals in the coarse fraction (>20um).
 

Monorthic -Kaolinite, halloysite and or fully hydroxy interlayered vermiculite (HIV) dominate the clay fraction. If smectite is present it should be at low concentrations such that it is not identifiable by appropriate mineralogical analyses (usually less than 10%). Usually the clay fraction CEC at pH 7 is < 30 meq/100g. Coarse fractions are typically siliceous (>90% quartz+resistant minerals).
 

Calcaric - Strongly calcareous bisiallitic soil material with more than 2% free carbonates in the surface horizon and throughout most of the solum.
 

Smectic - Biasiallitic soil material in which smectite is the dominant mineral in the clay fraction. Typically smectite content is more than 50 percent of the clay fraction.
 

Parasmectic - Biasiallitic soil material in which smectite is identified, but is not the dominant mineral, smectite content ranges from 10 to 50 percent of the clay fraction. Quartz is not the dominant mineral in the clay fraction.
 

Quartzismectic - Biasiallitic soil material in which quartz is the dominant mineral in the clay fraction. The smectite content is more than 10 percent of the clay fraction. This assemblage is typically found in northern Arkansas.
 

Biorthic - Typical bisiallitic soil material that consists of clay fractions containing appreciable amounts of vermiculite, mica and/or chlorite or identifiable amounts of smectite (usually > 10%). Various amounts of interstratified mica-vermiculite-chlorite, partially hydroxy-Al-interlayered vermiculite or smectite, and interstratified mica-smectite have been identified in the Southern Region. Cation exchange capacities are generally greater than 30 meq/100g of clay. Typically, coarse fractions contain greater than 10% weatherable minerals.