Soils 102 – Chemical properties

1. Soils 102 – Chemical properties

2. Soils 102 – Chemical properties It’s more than just salt ...

3. Outline • Introduction • Topics: • Nutrients • pH • salinity/sodicity • Practical matters • Summary

4. Introduction • Chemical elements ...

5. Nitrogen nitrate ammonium Phosphorous Potassium Calcium Magnesium Aluminum Sodium Hydrogen N NO3- NH4+ P (PO43-) K (K+) Ca (Ca2+) Mg (Mg2+) Al (Al3+) Na (Na+) H (H+) Chemical elements

6. Introduction • Chemical elements ... • Where are the nutrients, salts, etc.?

7. - - - - - - - - Mineral particle (sand, silt, clay) - - - - - - - - - - - - - - - - -

8. K+ - - Ca2+ Al3+ - - Mg2+ K+ - - - - Mineral particle (sand, silt, clay) - - - - - Al3+ Ca2+ - - K+ Mg2+ - - Fe2+ K+ -

9. Mg2+ H+ H+ K+ Ca2+ Al3+ Na+ K+ Ca2+ Mg2+ H+ H+ K+ Ca2+ Al3+ Na+ K+ Ca2+ Mg2+ H+ Mg2+ H+ Ca2+ Na+ Ca2+ H+ K+ Al3+ K+ - - Ca2+ Al3+ - - Mg2+ K+ - - - - Mineral particle (sand, silt, clay) - - - - - Al3+ Ca2+ - - K+ Mg2+ - - Fe2+ K+ - - - - - - - - Adsorbed to particle surface

10. Mg2+ H+ Ca2+ Na+ Ca2+ H+ K+ Al3+ Mg2+ H+ H+ K+ Ca2+ Al3+ Na+ K+ Ca2+ Mg2+ H+ H+ K+ Ca2+ Al3+ Na+ K+ Ca2+ Mg2+ H+ Mg2+ H+ Ca2+ Na+ Ca2+ H+ K+ Al3+ K+ - - Ca2+ Al3+ - - Mg2+ K+ - - - - Mineral particle (sand, silt, clay) - - - - - Al3+ Ca2+ - - K+ Mg2+ - - Fe2+ K+ - Available in soil water Adsorbed to particle surface

11. Nutrients • How are nutrients held to the mineral soil?

12. Negative charges on particle surface Mg2+ H+ Ca2+ Na+ Ca2+ H+ K+ Al3+ Mg2+ H+ H+ K+ Ca2+ Al3+ Na+ K+ Ca2+ Mg2+ H+ H+ K+ Ca2+ Al3+ Na+ K+ Ca2+ Mg2+ H+ Mg2+ H+ Ca2+ Na+ Ca2+ H+ K+ Al3+ - - - - - - - - Mineral particle (sand, silt, clay) - - - - - - - - - - Available in soil water Adsorbed to particle surface

13. Nutrients • How are nutrients held to the mineral soil? • Organic matter – another source

14. Organic matter Mg2+ H+ Ca2+ Na+ Ca2+ PO4- K+ Al3+ Mg2+ H+ NO3- K+ Ca2+ Al3+ Na+ K+ Ca2+ Mg2+ H+ PO4- K+ Ca2+ Al3+ Na+ K+ Ca2+ NO3- H+ Mg2+ H+ Ca2+ Na+ Ca2+ PO4- K+ Al3+ - - - - - - - - - - - - - - - + + -

15. Mg2+ H+ Ca2+ Na+ Ca2+ PO4- K+ Al3+ Mg2+ H+ NO3- K+ Ca2+ Al3+ Na+ K+ Ca2+ Mg2+ H+ PO4- K+ Ca2+ Al3+ Na+ K+ Ca2+ NO3- H+ + Mg2+ H+ Ca2+ Na+ Ca2+ PO4- K+ Al3+ - - - - - - + + - - - - - - - - - - - - - + - - + + + - - -

16. Mg2+ H+ Ca2+ Na+ Ca2+ PO4- K+ Al3+ PO4- Mg2+ H+ NO3- K+ Ca2+ Al3+ Na+ K+ Ca2+ Mg2+ H+ PO4- K+ Ca2+ Al3+ Na+ K+ Ca2+ NO3- H+ Na+ + Ca2+ Mg2+ H+ Ca2+ Na+ Ca2+ PO4- K+ Al3+ - - - - H+ - - + K+ + - NO3- - - - - - - Mg2+ - K+ - NH4+ - - - NO3- - + - - + + + - NO3- - - NH4+

17. pH

18. pH • A measure of acidity/alkalinity

19. pH • A measure of acidity/alkalinity 1 7 14 Acid Neutral Base

20. pH • A measure of acidity/alkalinity • Which nutrients are basic, acid? 1 7 14 Acid Neutral Base

21. pH • A measure of acidity/alkalinity • Which nutrients are basic, acid? • Basic – Ca2+, Mg2+, K+ , (Na+) • Acid – H+, Al3+, Sulfur 1 7 14 Acid Neutral Base

22. pH • A measure of acidity/alkalinity • Which nutrients are basic, acid? • Which of these predominate in the Plains? 1 7 14 Acid Neutral Base

24. pH • A measure of acidity/alkalinity • Which nutrients are basic, acid? • Which of these predominate in the Plains? • Average pH of ND soils? 1 7 14 Acid Neutral Base

25. Soil pH levels, upland positions, non-manured sites, 1998. (Franzen, 1999)

26. pH • A measure of acidity/alkalinity • Which nutrients are basic, acid? • Which of these predominate in the Plains? • Average pH of ND soils? • How pH affects nutrient availability 1 7 14 Acid Neutral Base

31. pH • A measure of acidity/alkalinity • Which nutrients are basic, acid? • Which of these predominate in the Plains? • Average pH of ND soils? • How pH affects nutrient availability • How pH affects tree survival and growth 1 7 14 Acid Neutral Base

32. pH and trees • Deciduous more tolerant of high pH than conifers are (Michigan jack pine example)

33. pH and trees • Deciduous more tolerant of high pH than conifers are (Michigan jack pine example) • Conifer needle litter reduces the soil pH over time

34. pH and trees • Deciduous more tolerant of high pH than conifers are (Michigan jack pine example) • Conifer needle litter reduces the soil pH over time • pH < 4  aluminum toxicity

35. pH and trees • Deciduous more tolerant of high pH than conifers are (Michigan jack pine) • Conifer needle litter reduces the soil pH over time • pH < 4  aluminum toxicity • Which conifers appropriate to high pH?

36. pH and trees • Deciduous more tolerant of high pH than conifers are (Michigan jack pine) • Conifer needle litter reduces the soil pH over time • pH < 4  aluminum toxicity • Which conifers appropriate to high pH? • Ponderosa pine • Rocky Mountain juniper • Eastern redcedar

39. Salinity

40. Salinity • High soluble salt concentration

41. Salinity • High soluble salt concentration • Not necessarily high sodium salts

42. NaCl Na2SO4 NaHCO3 Na2CO3 MgCl2 MgSO4 CaCl2 Sodium chloride Sodium sulfate Sodium bicarbonate Sodium carbonate Magnesium chloride Magnesium sulfate Calcium chloride Soluble salts

43. How do saline soils (seeps) develop?

44. How do saline soils (seeps) develop? • Salts already present (esp. W of Mo. Riv.)

45. How do saline soils (seeps) develop? • Salts already present (esp. W of Mo. Riv.) • Salts dissolve in water and move

46. How do saline soils (seeps) develop? • Salts already present (esp. W of Mo. Riv.) • Salts dissolve in water and move • Water evaporates, leaving concentrated salts

47. Saline soils in Grand Forks County (Seelig, 2000)

48. Formation of saline seeps (Seelig, 2000)

49. Salinity • High soluble salt concentration • Not necessarily high sodium salts • Measured by electrical conductivity (EC) • Units are mmhos or dS/m

50. Salinity • High soluble salt concentration • Not necessarily high sodium salts • Measured by electrical conductivity (EC) • Units are mmhos or dS/m • NDSU soils lab recommendations: • 0-1 Non-saline • 1-2 Very slightly saline • 2-4 Slightly saline • 4-6 Saline • >6 Strongly saline