GLY-1103 Lecture Notes - Lecture 5: Clay Minerals, Weathering, Soil Fertility
Monday, October 26, 2015
Soils
DIRT
-Soils
•soils: unconsolidated material capable of supporting plant growth
•regolith: unconsolidated material incapable of supporting growth
-Soil formation
•importance of soil:
•1/4 tsp of a fertile soil contains: 50 nematodes, 62000 algae, 111000 fungi,
72000 protozoa, 25000000 bacteria and 3000000 actinomycetes
•help with nutrient/water absorption: fungi and bacteria attach to roots, nitrogen
fixation
•recycle organic matter
-Mechanical weathering
•the physical break-up of rock without changing the chemical composition
•abrasion - water burring holes
•frost-wedging
•mechanical weathering increases surface area and ultimately the amount of
chemical weathering
•chemical weathering is twice as fast/efficient as mechanical
-Chemical weathering
•minerals reacting with: water, acid, chemicals dissolved in water, gasses in air
•oxidation - rxn with o2 and iron
•dissolution rxn - calcite passing “acid test”
•hydrolysis - addition of water mineral + acid + water = clay mineral
!1
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Document Summary
Soils: soils: unconsolidated material capable of supporting plant growth, regolith: unconsolidated material incapable of supporting growth. Soil formation: importance of soil, 1/4 tsp of a fertile soil contains: 50 nematodes, 62000 algae, 111000 fungi, 72000 protozoa, 25000000 bacteria and 3000000 actinomycetes: help with nutrient/water absorption: fungi and bacteria attach to roots, nitrogen. Biochemical/biomechanical weathering: chelating lichens, root wedging. Horizions: o horizon - organic material, a horizon - mineral-rich horizon, e horizon - light-colored zone of leaching. Wetland soils (histosols: characteristics - rich in organics, soft, bene ts - nutrient rich soil = diverse plant life, habitat for water birds, etc, ood control, sediment trap, lters pollutants, threatened because they"re cleared for farming/development. Loss of soil fertility: top soil attributes, permeable, nutrient-rich, retains moisture, soft (can lose all these things, what causes it, repeated tilling, clearing of natural vegetation, failed crops, too much grazing. !3: lose fertile soil, clouds waters, toxic, reduces storage, capacity/navigation (millions.
