ZINC
DEFICIENCY

Zinc in the soil appears to be related to organic matter accumulation. Many soils show higher zinc content near the soil surface. Zinc deficiencies occur principally in sandy soils formed from siliceous rocks such as gneiss, quartz or sandstone. Zinc exists in the soil as the Zn++ cation, exchangeable Zn and as organically complex Zn. Zinc is brought into contact with the plant roots by mass flow and diffusion, with diffusion being the primary delivery mechanism.
Research has shown that a relationship exists between phosphorus (P) and zinc (Zn). High phosphorus can interfere with zinc metabolism as well as affect the uptake of zinc through the roots. High soil pH also decreases the availability of soil phosphorus. High levels of soil zinc can induce an iron (Fe) deficiency.
Zinc deficiency in the plant has such an impact that terms like "little leaf" and "rosetting" are used to describe the symptoms. Rosetting is the failure of the internodes to elongate, causing the leaves of several nodes to grow close together. Zinc deficiency in corn and beans shows a dark green coloration along the midrib and a light yellow to white area between the veins. Seed formation may be reduced when zinc deficiency occurs.
Zinc sufficiency levels in the leaf range from 15-50 ppm in mature leaves. For the majority of crops, 15 ppm zinc is considered the critical value. Zinc deficiencies can be corrected by adding zinc to the soil or a foliar spray on the plants. Applied to the soil, 20-25 lbs. of zinc per acre as zinc sulfate can correct deficiencies. Mix 20-25 lbs. of basic zinc sulfate in 100 gals of water can and apply as a foliar spray at the rate of 20-25 gals/acre to get a more rapid plant response.