GEOB 102 Lecture Notes - Lecture 21: Kaolinite, Soil Horizon, Allophane

• School: UBC
• Department: Geographical Biogeosciences
• Course: GEOB 102
• Professor: Nina Hewitt

Document Summary

Soil profile: could be categorized into sub horizons and major horizons. Silicate clays and humus under the microscope --> these are the minerals that make up silicate clays and usually as a result of chemical weathering (or other chemical processes) Kaolinite (1:1 ratio) --> a product of feldspars, white, secondary silicate clay material. Montmorillonite (2:1 ratio) --> also called smectite, the ration is like this because it is expanding due to it"s ability to absorb large amounts of water. Plant nutrition and soil fertility is completely dependent on weathering (this type of process is essentially what creates silicate clay) and how weathering releases nutrient ions to the solution. Feldspar weathering: creates kaolinite (see above), a secondary white silicate clay material, also releases potassium ions into the solution (this process is considered a great plant nutrient) as well as soluble silica. This type of chemical weathering is essential to creating silica clays and also the supply of fresh nutrient ions.