• iron is one of the 13 essential elements for plant growth, and is considered a micronutrient based on the concentration required for plant growth
• principle form of uptake: ionic forms (Fe²⁺, Fe³⁺)
• amount required for healthy plant growth: 100 ppm, dry soil matter
• soil conditions related to iron deficiencies:
  • calcareous soils with low soluble iron
  • waterlogged soil
  • acid soil with excessive levels of manganese, zinc, copper and nitrogen
  • sandy soils low in total iron
  • peat & muck soils
• iron moves through soil primarily by diffusion
• soil factors that affect iron uptake by plants:
  • soil test levels (available iron in soil)
  • decomposition of organic matter
  • low pH (acidic) increases plant uptake of iron
  • high pH (basic) decreases plant uptake
• plant factors that affect iron uptake by plant:
  • hybrid or variety of plant
  • stage of growth
  • interactions with other elements
    • Zinc: excess zinc can induce an iron deficiency, particularly in those plants sensitive to iron

Roles of Iron in Plant Functions

• important component of many enzyme systems
• required component for NO₃ (nitrate) and SO₄ (sulfate) reduction
• required component for N₂ assimilation and energy (NADP) production
• functions as a catalyst for chlorophyll production
• thought to be involved in root-tip meristem growth
• the plant and soil chemistry that involves iron is very complex and is still under intensive study