Unformatted text preview: c 0.06 kg oxide clay x 2 cmol c /kg = 0.12 cmol c 0.69 kg kaolinite x 10 cmol c /kg = 6.9 cmol c 1.25 pts (0.25, 0.25, 0.75) 3. The soil in problem 1 contains 38 % clay. The soil in problem 2 contains 75 % clay. Explain why the soil with the most clay has the lower CEC. Lower cation exchange capacity of the oxide clay and kaolinite 4. Define CEC. What are the two major sources of charges on soil colloids that result in CEC? 0.75 pts The amount of exchangeable cations per unit weight of dry soil 0.75 pts Ionizable H ions (pH dependent) 0.75 pts Isomorphous substitution (substitution of one ion for another of similar size and often lower positive valence)...
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- Fall '07
- Ion, cation exchange capacity, CEC, kg humus, Kaolinite Sesquioxides, Component Humus Vermiculite