Lecture 13 Review and Soil Acidity

Lecture 13 Review and Soil Acidity - Soil Acidity and...

Info iconThis preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Soil Acidity and Review of Colloid Charge Mineral Charge Positive charge Al 3+ Si 4+ Negative charge OH-O 2- Perfect Mineral = Si Al Tetrahedral Substitution Al 3+ for Si 4+ Positive charge Al 3+ Si 4+ Negative charge OH-O 2-= Al Aluminum contributes less (+) charge than silicon Octahedral Substitution Mg 2+ for Al 3+ Positive charge Al 3+ Si 4+ Negative charge OH-O 2-= Magnesium contributes less (+) charge than Aluminum Na + Na + Na + Na + Na + Na + Na + Charge K H O H H O + Hydrated Cations Smectites Significant substitution in the octahedra Ca 2+ Mg 2+ Na + Cations satisfying charge CEC = 80-120 cmol c kg Layers weakly held together by cations Highly expansible Mg 2+ Mg 2+ Source of negative charge Is very close to the adsorbed cations Layers tightly bound Moderately expansible Vermiculite Significant substitution in tetrahedra CEC = 100-180 cmol c kg Soil Organic Matter and Reactivity The functional groups on organic colloids are weak acids. Acids give up hydrogen ions (H+) to water. HCl H + + Cl-Strong acids give up all their H + ions Weak acids give up some of their H + ions COOH COO-+ H + OH O + H + Soil Solution COOH COO-+ H + Dissociation of weak acid functional groups results in the development of negative charge The amount of negative charge depends on how much dissociation takes place Low pH = lots of H + = less dissociation = low charge High pH = little H + = more dissociation = high charge The dissociation is inhibited by H + in soil solution COOH...
View Full Document

This note was uploaded on 07/31/2011 for the course SOS 3022 taught by Professor Staff during the Fall '08 term at University of Florida.

Page1 / 42

Lecture 13 Review and Soil Acidity - Soil Acidity and...

This preview shows document pages 1 - 13. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online