Micronutrients For Your Plant Growth
Micronutrients are essential for plant growth and play an important role in balanced crop nutrition. They include boron, copper, iron, manganese, molybdenum, zinc, nickel and chloride.
They are as important to plant nutrition as primary and secondary macronutrients, though plants don't require as much of them. A lack of any one of the micronutrients in the soil can limit growth, even when all other nutrients are present in adequate amounts.
Through soil testing and plant analyses, micronutrient deficiencies have been verified in many
soils. Some reasons limiting the incidental additions of micronutrients include:
• High-yield crop demands remove micronutrients from the soil
• Increased use of high-analysis NPK fertilizers containing lower quantities of micronutrient
• Advances in fertilizer technology reduce the residual addition of micronutrients.
These factors contribute to the significant increase in usage of and need for micronutrients in
order to achieve full balanced nutrition.
Boron (B), one of the most important micronutrients affecting membrane stability, supports
the structural and functional integrity of plant cell membranes. Boron-deficiency symptoms first
appear at the growing points, and certain soil types are more prone to boron deficiencies.
Copper (Cu) activates enzymes and catalyzes reactions in several plant-growth processes. The
presence of copper is closely linked to Vitamin A production, and it helps ensure successful
Iron (Fe) is essential for crop growth and food production. Iron is a component of many
enzymes associated with energy transfer, nitrogen reduction and fixation, and lignin formation.
Manganese (Mn) activates several important metabolic reactions and plays a direct role in
photosynthesis. Manganese accelerates germination and maturity while increasing the
availability of phosphorus (P) and calcium (Ca).
Molybdenum (Mo) is vital for the process of symbiotic nitrogen (N) fixation by Rhizobia
bacteria in legume root modules. Considering molybdenum’s importance in optimizing plant
growth, it's fortunate that Mo deficiencies are relatively rare in most agricultural cropping areas.
Zinc (Zn) was one of the first micronutrients recognized as essential for plants and the one
most commonly limiting yields. Although Zinc is required only in small amounts, high yields are
impossible without it.
Chlorine (Cl) is active in energy reactions in the plant. Most Chlorine in soils comes from salt
trapped in parent materials, marine aerosols and volcanic emissions.
Nickel (Ni) is important in plant nitrogen metabolism because it is a component of the urease
enzyme. Without the presence of Nickel, urea conversion is impossible. It is required in very
small amounts, with the critical level appearing to be about 0.1 ppm.
Application with Mixed Fertilizers
The most common method of micronutrient application for crops is soil application.
Recommended application rates usually are less than 10 lb/acre (on an elemental basis), so
uniform application of micronutrient sources separately in the field is difficult. Therefore, both
granular and fluid NPK fertilizers are commonly used as carriers of micronutrients. Including
micronutrients with mixed fertilizers is a convenient method of application, and allows more
uniform distribution with conventional application equipment. Costs are also reduced by
eliminating a separate application.