1. Rock Weathering and Soil Mineralogy

2. Physical Weathering……

3. I.Weathering A. Chemical Weathering 1.Water is critical (and heat serves as a catalyst) 2.Complex Process (involves several reactions) 3.Biological Activity (helps accelerate weathering processes)

4. 1.Complex Process Solution Hydrolysis Oxidation Hydration Chelation Dialysis Chemical Reconstitution

5. The negative log of hydrogen ion content “The negative log of hydrogen in concentration”

7. 6.02214129(27)×10 23 atoms Moles per liter

8. Concentration of H + * Concentration of OH - = 10 -14 [10 -7 ][10 -7 ] = 10 -14 “Always a constant”

9. Concentration of H + * Concentration of OH - = 10 -14 [10 -7 ][10 -7 ] = 10 -14 “Always a constant” pH of 0.1 M HCl = 10 -1 M = log 10 -1 = -1 = pH is 1 pH of 1 M HCl = 10 0 M = log 10 0 = 0 = pH is 0 pH: “The negative log of hydrogen in concentration”

10. “How much carbonic acid is there in rainwater?” pH: “The negative log of hydrogen in concentration”

11. pH: “The negative log of hydrogen in concentration”

12. Why does it matter?

13. Ca 2+ > Na + > Mg 2+ > K + > Si 4+ > Fe 3+ > Al 3+ Most Mobile Least Mobile

14. Molar BA Ratio

15. Uncle Festus Cuzzin Cletus

16. Molar BA Ratio Moles of Na 2 O + K 2 O + CaO + MgO Moles of Al 2 O 3

22. LiOH - lithium hydroxide NaOH - sodium hydroxidesodium hydroxide KOH - potassium hydroxidepotassium hydroxide HCl - hydrochloric acid HNO 3 - nitric acid H 2 SO 4 - sulfuric acidhydrochloric acidnitric acidsulfuric acid

30. Cation Exchange Capacity (CEC): The amount of exchangeable cations that a given weight of soil is capable of holding

32. CEC is measured in units of Cmol/kg, which replaces milliequivilents (meq)/100 g.

33. Wt. of 1 meq. = mole weight (g) charge of ion * 1000 Ex: the weight of 1 meq. of calcium is: 1 meq. Of Ca 2+ = 40.08 g= 0.02 g (2) * 1000

35. Ex: the weight of 1 meq. of calcium is: 1 meq. Of Ca 2+ = 40.08 g= 0.02 g (2) * 1000 So….the CEC of a soil containing 1.0316 g of exchangeable Ca 2+ per 100 g of soil is: 1.0316 g (wt. of exchangeable Ca 2+ ) 0.02 (wt. of 1 meq. of Ca 2+ )

36. Ex: the weight of 1 meq. of calcium is: 1 meq. Of Ca 2+ = 40.08 g= 0.02 g (2) * 1000 So….the CEC of a soil containing 1.0316 g of exchangeable Ca 2+ per 100 g of soil is: 1.0316 g (wt. of exchangeable Ca 2+ ) 0.02 (wt. of 1 meq. of Ca 2+ ) = 51.58 meq. =51.58 meq. Per 100 g, or 51.58 Cmol + /kg

37. C. CEC Capacities

38. Base Saturation

39. Base Saturation: the percentage of cation exchange capacity of a soil occupied by basic cations. In general, the higher the base saturation, the higher the pH of the soil. Why important? Plant growth Plant protection

40. Alfisols Ultisols Mollisol

41. Alfisols Ultisols Mollisol base saturation between 35% - 50% base saturation less than 35% base saturation greater than 50%