ABSTRACT
A number of elements that are required by plants in very small quantities are known as micronutrients or trace elements. The micronutrients that are essential for plant growth are zinc, copper, iron, manganese, boron, molybdenum, and chlorine. Boron and molybdenum are unique micronutrients because they exist in the soil as either anions or uncharged molecules. Copper and Zinc occur in the earth's crust primarily as sulfide minerals. Igneous rocks contain larger amounts of Cu and Zn than do sedimentary rocks, and both elements concentrate more in basalt than in granite. Manganese sulfate has been the most satisfactory material for most situations. Iron is the least mobile of the micronutrients in plants. When the deficiency appears, it is on the new growth and may be very severe. Certain trace elements are essential for animal growth and generally are furnished to the animals by the plant material consumed.
