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Soils 102 – Chemical properties

Soils 102 – Chemical properties. Soils 102 – Chemical properties. It’s more than just salt. Outline. Introduction Topics: Nutrients pH salinity/sodicity Practical matters Summary. Introduction. Chemical elements. Nitrogen nitrate ammonium Phosphorous Potassium Calcium Magnesium

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Soils 102 – Chemical properties

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  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

  23. 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

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

  25. 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

  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 • How pH affects tree survival and growth 1 7 14 Acid Neutral Base

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

  28. 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

  29. 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

  30. 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?

  31. 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

  32. Salinity

  33. Salinity • High soluble salt concentration

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

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

  36. How do saline soils (seeps) develop?

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

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

  39. 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

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

  41. Formation of saline seeps (Seelig, 2000)

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

  43. 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

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