The Micronutrients & Plant Growth - Copper's Role
Copper (Cu) is involved as an enzyme activator and is thought to be involved in chlorophyll formation although its specific role is still unclear. It is also considered to be involved in protein synthesis.
Small grains, particularly oats, are more sensitive to copper deficiency compared to other crops. Symptoms generally appear on young plants. The first symptoms are yellowing of the youngest leaves accompanied by slightly stunted growth. In cases of severe deficiency, the younger leaves turn pale yellow. Then the leaf tips curl downward, eventually turn brown, and die. This symptom is referred to as "leaf tip die back" and is most pronounced on small grains. In extreme cases, leaves become shriveled, twisted, broken, and ragged, and ultimately the plant dies. Copper deficiency can be corrected by adding a small amount of copper fertilizer to the soil.
Several materials are available for supplying copper and are available in both liquid and solid forms. Since the amount required is quite small compared to other fertilizers, blending dry micronutrient sources uniformly with regular fertilizer materials is difficult to achieve. Granular copper sulfate (25% Cu) and liquid copper (8% Cu) are the most common sources used for blending. Maximum benefit is achieved by uniform application and incorporation into the soil. A single application will generally be adequate for several years.