A zinc deficiency will delay edible bean maturity and decrease yield. Gray or brown irregular spots may appear on older leaves. Zinc sulfate is the most common dry fertilizer and zinc chelates are the most common liquid material. Soil application of zinc sulfate is the most common and most successful long-term strategy for eliminating zinc deficiencies. Zinc sulfate can be applied as a broadcast treatment and tilled into the soil or applied in a band near the seed.
Band application is most effective when placed to the side and below the seed.
Zinc chelates are generally used as a rescue treatment and do not result in any benefits to following crops. This requires more attention be paid to the zinc level in the soil. If a current soil test shows that zinc levels are low, zinc fertilizer is required. This can be accomplished by applying granular zinc sulfate or foliar zinc chelate. The major concern when rotations are changed is that producers may not know these crops are more sensitive to zinc than crops such as wheat and barley.