Plant Nutrients Notes

Excerpted from Idaho Master Gardeners Program Handbook Chapter 5

Essential Nutrients

  1. Plants obtain from the soil 14 of the 17 elements essential to their growth.
  2. The other three elements — carbon, hydrogen, and oxygen — come from the water and from the air.

Macronutrients - large quantities are required

  1. Primary macronutrients
    • Nitrogen (N) generally is for leaf or vegetative growth
    • Phosphorus (P or in fertilizers, designated as phosphate, P2O5) for root and fruit production
    • Potassium (K or in fertilizers, designated as potash, K2O) general plant health, cold hardiness, disease resistance, and general durability.
  2. Secondary macronutrients: Calcium (Ca), Magnesium (Mg), Sulfur (S),

Micronutrients - small quantities are required

  1. Deficiencies in these nutrients are less common.
  2. Soil pH is a significant factor in micronutrient availability
  3. In low pH toxicity can be a problem for: Boron (B), Copper (Cu), Iron (Fe), Manganese (Mn), Molybdenum (Mo), Zinc (Zn), Chlorine (Cl), Nickel (Ni)

General Nutrient Deficiency Symptoms

  1. Symptoms are an indication of severe starvation.
  2. Plant production limited before symptoms show !
  3. Deficiency difficult to distinguish visually and may resemble disease or insect problems.
  4. Categorized whether or not the nutrient is translocated in the plant.
    1. Translocated Nutrients
      1. Symptoms in the lower, or older, leaves because the nutrients are mobile and move to new, growing parts of the plant.
      2. Nitrogen (N) - Plants are light green in color; older leaves yellow starting at the leaf tips.
      3. Phosphorus (P) - Plants are small and dark green with purple coloration.
      4. Potassium (K) - Yellow or brown discoloration appears along the outer margins of the older leaves.
      5. Magnesium (Mg) - Yellow discoloration occurs between the leaf veins. Reddish-purple discoloration extends from the outer edge of the leaf inward.
    2. Non-Translocated Nutrients
      1. Terminal bud dies
        1. Calcium (Ca) - Primary leaf emergence is delayed, and terminal buds deteriorate.
        2. Boron (B) - Leaves near the growing point (meristem) are yellow, and buds look like white or light brown dead tissue.
      2. Terminal bud remains alive
        1. Sulfur (S) - The whole leaf turns pale green to yellow starting with the younger leaves.
        2. Zinc (Zn) - Distinctive yellowing appears between the leaf veins; some plants show a broad band of discoloration on each side of the midrib. The plant is stunted and has short internodes.
        3. Iron (Fe) - Leaves are pale yellow or white between leaf veins.
        4. Manganese (Mn) - Leaves are yellowish gray or reddish gray with green veins.
        5. Copper (Cu) - Young leaves are pale yellow and/or are wilted or withered; seed heads may not form.
        6. Chlorine (Cl) - Upper leaves wilt then yellow.
        7. Molybdenum (Mo) - Young leaves wilt and die along the margins; older leaves yellow due to their inhibited ability to utilize N.