There are many soil and environmental factors that affect the availability of micronutrients to plants. The major factors include: pH, organic matter content, nutrient interactions, soil water content, temperature, and light. For example:
Availability of boron, copper, iron, manganese, and zinc decreases dramatically with increasing soil pH.
Poorly drained soils may lead to manganese or zinc deficiencies.
Cold, wet soils may induce a zinc deficiency.
Soils low in organic matter, especially sandy soils, may be low in all micronutrients, especially zinc and copper.

Soils high in organic matter may tie up manganese and copper into unavailable complexes.
Excessive levels of other plant nutrients, especially phosphorus or calcium may induce micronutrient deficiencies.

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