NRES 201 Lecture 9 Outline of Last Lecture I Rationale for classification II Soil taxonomy Outline of Current Lecture III The benefit of taxonomy IV Soil orders V Lower level taxonomic categories Current Lecture The benefit of taxonomy Soils are inherently heterogeneous but they can be grouped according to common properties Huge potential for simplification from 23 000 series to 12 orders Soil orders Entisols o Dominant soil forming factor time o Few if any profile features o No diagnostic B horizon o Diverse group that includes Floodplain soils sand dunes steeply sloping soils soils subject to human disturbance o 5 suborders Aquents wet Arents disturbed Fluvents alluvial Orthents typical Psaments sandy Inceptisols o Dominant soil forming factor time o Inception of profile development o Cambic B horizon o 6 suborders Anthrepts man made Aquepts wet Cryepts cold These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Udepts humid Ustepts semiarid Xerepts dry summer moist winter Mollisols o Dominant soil forming factor organisms vegetation o High in native fertility o 7 major suborders Albolls albic horizon Aquolls wet Cryolls cold Rendolls calcareous Udolls humid Ustolls moist dry Xerolls dry summer moist winter Alfisols o Dominant soil forming factor organisms vegetation o Deciduous forest soils Spodosols o Dominant soil forming factor organisms vegetation o Spodic B horizon o Low in native fertility acidic Ultisols o Dominant soil forming factor climate o Develop under warm to tropical forests o Low in native fertility Oxisols o Dominant soil forming factor climate o Highly weathered Histosols o Dominant soil forming factor topography Vertisols o Dominant soil forming factor parent material Aridisols o Dominant soil forming factor climate Andisols o Dominant soil forming factor parent material Gelisols o Dominant soil forming factor climate Lower level taxonomic categories Suborders o Total of 29 o Many indicate a moisture or temperature regime for soil formation Great groups o Total more than 400 Subgroups o Total more than 2500 Families o Total about 800 o Based on temperature regime texture mineralogy Series o Total about 23000 for USA o Defined by horizon characteristics
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