Plant Nutrition 101

Essential Elements

There are 13 essential elements for plant growth:

  • 6 are considered Major Elements: 
  • 7 are considered Micronutrients:
  • These elements are primarily taken up through the roots
  • Root uptake is determined by the plant’s need for specific nutrients
  • element uptake is substantial during rapid vegetative growth and development, but as the plant approaches maturity, uptake declines
  • an element must be in its ionic form in the soil solution to be absorbed by the plant roots
  • the soil solution is the moisture that is in the soil, which has dissolved ions in it, ready to be taken up by roots as they need it
  • the availability of the elements in the soil solution is dependent on several factors:
    • moisture level of the soil
    • pH of the soil solution
      • low pH (acidic) increases Mn, Fe, and Al uptake, but decreases Mg and P uptake
      • high pH (basic) increases Mo, but decreases Fe, Al, Mn, Zn, and B uptake
    • temperature (N, P, K, S, Mg, B, Zn)
    • interactions between some elements:
      • Phosphorous & Zinc
      • Phosphorous & Manganese
      • Potassium vs. Calcium vs. Magnesium

Xylem & Phloem

  • Upward movement of water and ions is handled by the xylem
    • transpiration of water by the plant draws more water up, like sucking on a straw
    • the rate of transpiration is mostly what determines the rate of the upward movement
    • the rate of flow in the xylem ranges from 10 to 100 cm/hr
    • there’s also pressure from the roots, pushing water & ions up the straw
  • downward movement of sugars and other metabolic products are channeled by the phloem
    • but the movement can go both up & down, depending on the plant’s need to shuttle elements around based on need
    • the rate of flow in the phloem is way slower than in the xylem
    • the phloem is made up of living cells
  • there is some cross-transfer from the xylem into the phloem

Sources

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