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Lecture #6 – Plant Nutrition and Soils

Lecture #6 – Plant Nutrition and Soils. Image – a soil profile. Key Concepts:. Resources Which are required How they are used Essential elements What they are What they do Soils and soil forming factors The rhizosphere Some alternate methods to acquire nutrients.

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Lecture #6 – Plant Nutrition and Soils

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  1. Lecture #6 – Plant Nutrition and Soils Image – a soil profile

  2. Key Concepts: • Resources • Which are required • How they are used • Essential elements • What they are • What they do • Soils and soil forming factors • The rhizosphere • Some alternate methods to acquire nutrients

  3. Resource requirements for plant growth??? ?

  4. Where do plants get these resources??? ?

  5. Where do plants get these resources???

  6. Image – root system of a grass Diagram – plant resource requirements and sources

  7. Plant tissue composition by weight: • Fresh herbaceous tissue is 80-85% water • Little water is incorporated into plant tissue • What does water contribute to tissue??? • Most water is in the cell solution, in the vacuoles, or passing through in the transpiration stream

  8. Critical Thinking • Does wood have such a high percentage of water???

  9. Critical Thinking • Does wood have such a high percentage of water??? • Typically not – wood is dead tissue and xylem often becomes plugged up by resins, etc in the interior of the tree • This is what we call “heartwood” and it is often very beautiful

  10. Plant tissue composition by weight: • Fresh herbaceous tissue is 80-85% water • Little water is incorporated into plant tissue • What does water contribute to tissue??? • Most water is in the cell solution, in the vacuoles, or passing through in the transpiration stream

  11. Plant tissue composition by weight: • Fresh herbaceous tissue is 80-85% water • Little water is incorporated into plant tissue • Water supplies all the H to carbohydrates; electrons and protons for photosynthesis • Most water is in the cell solution, in the vacuoles, or passing through in the transpiration stream

  12. Plant tissue composition by weight: • Fresh herbaceous tissue is 80-85% water • Little water is incorporated into plant tissue • Water contributes H to carbohydrates; electrons and protons for photosynthesis • Most water is in the cell solution, in the vacuoles, or passing through in the transpiration stream

  13. Each a tad under 45% DRY plant tissue composition by weight: • 45% carbon • 45% oxygen • 6% hydrogen • 5% inorganic mineral nutrients

  14. DRY plant tissue composition by weight: • 45% carbon – from ?? CO2 • 45% oxygen – from ?? CO2 • 6% hydrogen – from ?? water • 5% inorganic mineral nutrients – from ?? soil

  15. DRY plant tissue composition by weight: • 45% carbon – from CO2 • 45% oxygen – from • 6% hydrogen – from • 5% inorganic mineral nutrients – from

  16. DRY plant tissue composition by weight: • 45% carbon – from CO2 • 45% oxygen – from CO2 • 6% hydrogen – from water • 5% inorganic mineral nutrients – from

  17. C, H, O – source and fate in photosynthesis Diagram – what goes into photosynthesis and what comes out

  18. DRY plant tissue composition by weight: • 45% carbon – from CO2 • 45% oxygen – from CO2 • 6% hydrogen – from water • 5% inorganic mineral nutrients – from soil • 0.75-1% of wet weight, but many are essential to plant growth and function

  19. Critical Thinking • What is the difference between a chemical element, a molecule and a macromolecule???

  20. Critical Thinking • What is the difference between a chemical element, a molecule and a macromolecule??? • N vs. N2vs. chlorophyll Diagram – structure of chlorophyll molecule

  21. Essential Elements • Chemical elements • Not molecules, though some are delivered in that form – N vs. NO3- • Required for growth and function of the plant • Can’t be replaced by some other element • Some contribute to structural components • Some contribute to metabolic processes or the maintenance of homeostasis

  22. Essential elements in structural plant components: • What are some essential molecules used in structural components??? ?

  23. Essential elements in structural plant components: • Cellulose – ?? • Lignin – ?? • Pectin – ?? • Cell membranes – ?? • Proteins (cell membrane, cytoskeleton) – ??

  24. Essential elements in structural plant components: • Cellulose – C, H, O • Lignin – C, H, O, S • Pectin – C, H, O, Ca • Cell membranes – C, H, O, P • Proteins (cell membrane, cytoskeleton) – C, H, O, N, sometimes S Note – C H and O are in ALMOST ALL organic molecules

  25. Essential elements for metabolic processes: • What are some essential molecules used in metabolic processes??? ?

  26. Essential elements for metabolic processes: • Chlorophyll – ?? • Nucleic acids – ?? • ATP – ?? • Enzymes and other proteins – ?? • Enzyme cofactors – ?? • Elements that control water, charge and solute balance – ??

  27. Essential elements for metabolic processes: • Chlorophyll – C, H, O, N, Mg • Nucleic acids – C, H, O, N, P • ATP – C, H, O, N, P • Enzymes and other proteins – C, H, O, N..S • Enzyme cofactors – many micronutrients • Elements that control water, charge and solute balance – K, Cl, P, Ca, others Note – C H and O are in ALMOST ALL organic molecules

  28. Nitrogen Potassium Calcium Magnesium Phosphorous Sulfur Chlorine, Iron, Boron, Manganese, Zinc, Copper and Molybdenum Some plants also require Nickel, Sodium, Silicon, Selenium or others Macro Nutrients vs. Micro Nutrients mass All used in large quantities to support the structures and processes listed before Mostly used in enzymes, as enzyme cofactors or in electron transfers – often reused, less required

  29. Study table in book! Table – essential nutrients, both macro and micro

  30. Memory device in honor of my friend and mentor, Dr. Chuck Davey – celebrated in 2006 for 50 years of service to soil science!!! “C HOPKNS CaFe, Mg, Mn B CuZn Mo, Cl” C. Hopkin's cafe, mighty good, managed by cousin Mo, waitress Clara Nickel may also be essential

  31. Some minerals required, some by chance… Images – various plants that use additional elements Sulfur in mustards Silicon in horsetails Uranium in macadamia nuts

  32. Critical Thinking • How do you tell which are required???

  33. Critical Thinking • How do you tell which are required??? • Hydroponics! Diagram – a hydroponic experiment

  34. Critical Thinking • How do you tell which are required??? • Hydroponics! • How would elements NOT required enter the plant tissue???

  35. Critical Thinking • How do you tell which are required??? • Hydroponics! • How would elements NOT required enter the plant tissue??? • They are pulled toward the root in the transpiration stream, and enter through any membrane channel they can fit through

  36. All plants will exhibit signs of deficiencies….. Images – signs of deficiency

  37. Critical Thinking • If the deficiency appears first in the older leaves, is that nutrient mobile or immobile???

  38. Critical Thinking • If the deficiency appears first in the older leaves, is that nutrient mobile or immobile??? • Mobile – it’s being translocated from the older tissues to the new, growing tissues • How???

  39. Critical Thinking • If the deficiency appears first in the older leaves, is that nutrient mobile or immobile??? • Mobile – it’s being translocated from the older tissues to the new, growing tissues • How??? • In the phloem!!! • The older tissue acts as a source • The younger tissue is the sink

  40. Fe deficiency in younger leaves (immobile) Mg deficiency in older leaves (mobile)

  41. Critical Thinking • Why would some elements be mobile, and others not???

  42. Critical Thinking • Why would some elements be mobile, and others not??? • Must be soluble in water – phloem sap is water based… • Some get locked into membranes or other components that can’t be broken down

  43. Most plants get most of their nutrients from the soil – absorbed through the roots Image – roots

  44. Soil is not just Dirt! • Soil is the “skin” of the earth • Soil provides for virtually all our food • Soil supports the forests that maintain the hydrological cycle • Soil supports virtually all terrestrial ecosystems – from micro-organisms to charismatic macro-fauna

  45. The results of deforestation are ecological, economic and social disaster () Rosie Image – erosion after tropical deforestation

  46. Removing the plants removes the soil’s protective “blanket” and erosion is almost inevitable

  47. Erosion from deforestation in Madagascar More images – erosion

  48. Sedimentation from erosion – this represents a huge loss of soil “capital” Image – sediments from eroded land flooding out to sea

  49. Sediments eroding off Haiti Image – sediments eroding off Haiti into the sea

  50. Dominican Republic Image – the political boundary is clear from the deforestation Haiti

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