Pedology and Soil Geomorpholgy

Pedology and Soil Geomorpholgy: 

Pedology and Soil Geomorpholgy Pedology: the science devoted to understanding how soils developed, relationships to environment, and their geography Soils: why are they unique? -Hans Jenny: soils unique because they represent the “meeting ground” between the atmosphere, lithosphere, biosphere, and hydrosphere Soils are dynamic,especially under conditions of changing climate and vegetation

Soil Terms: 

Soil Terms Pedon: a soil individual whose size is about 1 m2, but whose boundaries are often hard to define Soil Profile: sequence of layers, or horizons, from the land surface which are distinct in physical and chemical characteristics Horizons: unique layers: the eluvial horizon, the illuvial horizon Parent Material: the earth materials in which the soil develops. At beginning, soils tend to be little altered parent material Eluviation: removal of materials chemically, with changes chemical changes in movement. Illuviation: deposition of chemically altered materials in lower horizon Translocation: movement without chemical alteration

Soil Characteristics: 

Soil Characteristics Physical Characteristics -color: red = iron oxide; black = organic matter; green-gray = reducing -structure: how peds are arranged. Subangular characteristic of brown forest soils, prairie soils -Particle Size/grain size = amount of sand, silt, clay in soil. Determines reactivity, permeability, bearing strength, etc. -types of horizons present, their thickness, total depth of soil profile

Soil Chemical Characteristics: 

Soil Chemical Characteristics pH: soil reaction: whether acidic, neutral, or alkaline CEC: cation exchange capacity Components of soil organic matter -what type of organic acids -influence on CEC -influence on soil permeability and structure -inlfuence on soil fertility

Major Soil Orders: 

Major Soil Orders Spodosols: coniferous or heath soils Alfisols: brown forest soils Mollisols: grassland soils Ultisols: weathered southern forest soils Aridisols: desert soils Oxisols: soils of the tropical rainforest and savanna

Unique Soil Orders: 

Unique Soil Orders Inceptisols: river floodplain soils Entisols: soils too young to have mature characteristics Histosols: organic soils Andosols: immature volcanic soils

Soil Geomorphology: 

Soil Geomorphology Topographic relationships -changes in soils texture across slope -toposequence Temporal relationships -chronosequence: changes in soil characteristics over time on same type of parent material Much of the work done in eastern Iowa on loessal landscapes