NRES 201 Lecture 9 Outline of Last Lecture I. Rationale for classificationII. Soil taxonomy Outline of Current Lecture III. The benefit of taxonomyIV. Soil ordersV. Lower - level taxonomic categoriesCurrent LectureThe 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 ordersSoil orders - - Entisols - o Dominant soil forming factor: timeo Few, if any profile featureso 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: timeo Inception of profile developmento Cambic B horizono 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 horizono Low in native fertility (acidic)- Ultisols - o Dominant soil forming factor: climateo Develop under warm to tropical forestso Low in native fertility - Oxisols - o Dominant soil forming factor: climateo 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: climateLower level taxonomic categories - - Suborderso Total of 29o Many indicate a moisture or temperature regime for soil formation - Great groups o Total more than 400- Subgroupso Total more than 2500- Familieso Total about 800o Based on temperature regime, texture, mineralogy - Serieso Total about 23000 for USAo Defined by horizon
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