ENVS 2060 Lecture Notes - Lecture 19: Cation-Exchange Capacity, Soil Ph, Loam
31 Mar 2016
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Document Summary
Equilibrium between cations on exchange sites and in soil water. When offset: more hydrogens in soil water, more hydrogens in cation exchange site. Good relationship between ph and base saturation: ph decrease more hydrogen in soil water, more hydrogens on exchange site, decrease in base saturation, if ph is 6. 8 base saturation = approx. Soil 1: cec 30 cmol kg, ph = 5. 0, b. s. Use molecular masses of the ca, c, and o3. The bigger the particle size, the less reactive it is, which would mean some will not react and be left behind. Sandy loam: cec 10 cmol kg, ph = 5. 0, b. s. Ie: 60% of q0 cmol kg = 6 mol of h+ replaced, 6 cmol (1/2 caco3) required. Needs less because of lower cec and fewer hydrogens had to be reacted off to change the ph. Base saturation drops faster = ph drops faster.
