REN R210 Lecture Notes - Lecture 2: Pedogenesis, Aeration, Silt
27 Sep 2016
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Soils lecture 2 (see notebook for factors of soil formation) Moisture content: moisture increases, value decreases (gets darker) Drainage condition: imperfect draining will lead to gleying creating blue/grey colours due to fluctuating water tables. Redox conditions in gleyed areas: oxidized fe3+ is bright red, reduced fe2+ has a gleyed colour, patches of colour on a different background colour called mottles are created, usually red patches on gleyed background. Roots make channels and grow down and when they die, they leave behind pore space for oxygen and particles to travel through causing colour changes. Rooting depth/ volume (heavy clays lead to compaction or shrink/swell) Erosion control (wind and water can transport sand and silt) Surface areas: clay has the largest sa to volume ratio, then silt, then sand, because it s so big for clay, it has important physical and chemical properties.
