State the amount of micronutrients in fertilizers

The amount of micronutrients in fertilizers must be much more carefully controlled than the macronutrients. The difference between the deficiency and toxicity levels of a given micronutrient is extremely small. Consequently, micronutrients should be added only when their need is certain and when the amount required is known. When a trace element deficiency is to be corrected, a salt of the lacking nutrient is usually added separately to the soil.