Micronutrient

Quick definition

Trace elements (iron, zinc, manganese, magnesium, boron, molybdenum) needed in small quantities for plant health, enzyme function, and photosynthesis.

In plain terms

Plants need micronutrients in tiny amounts, but they're essential. Iron produces chlorophyll (green color). Magnesium is the center of chlorophyll molecules. Zinc, manganese, and boron are enzyme cofactors. Deficiency in any micronutrient causes specific visible symptoms: iron deficiency causes yellowing (chlorosis); magnesium deficiency causes yellow leaves with green veins. Most soils have adequate micronutrients; deficiency is usually pH-related (nutrients are locked away) or very sandy soil (leached away).

Why this matters

Micronutrient deficiency causes yellowing and stunting despite adequate macro-nutrition. Recognizing micronutrient deficiency symptoms helps diagnose problems.

In practice

Examples

Iron-deficiency chlorosis: yellow leaves with green veins; fix with iron fertilizer or lower soil pH to release locked iron.
Magnesium deficiency: yellow leaves with green veins (similar to iron but slightly different pattern); fix with Epsom salt spray.
Boron deficiency: deformed new growth; uncommon but possible in sandy, heavily leached soils.
Zinc deficiency causes stunted growth; foliar spray with zinc sulfate corrects deficiency quickly.

Practical applications

If leaves yellow while plant grows, suspect micronutrient deficiency or disease.
Foliar spray with fish emulsion or seaweed provides trace elements; good maintenance practice.
Micronutrient deficiency is usually pH-related; raising or lowering pH releases locked nutrients.
Compost additions provide micronutrients; complete fertilizers include micronutrients.
Soil test can diagnose micronutrient deficiency; apply targeted micronutrient fertilizer if needed.

Connected terms

Learn these first

Nutrient Chlorophyll Photosynthesis