In 1987 foliar and soil applications of zinc sulphate and zinc chelate failed to increase yield of cotton which had a deficiency of zinc in leaf tissues. This was because none of the zinc amendments changed the zinc concentration detected in the leaves.

In 1988 additional treatments were tried to correct the zinc deficiency in the same field. In addition to the soil and foliar applications of sulphate and chelate, the effects of enhancement by ammonium sulphate was tested. Ammonium sulphate is presently listed on the label of several herbicides to enhance the effectiveness of the compounds.

The yield and zinc concentration in leaf tissues of this test is shown in Table 1. The zinc concentration was successfully improved when ammonium sulphate was included in the foliar spray. Unfortunately, an attack of beat armyworms fed selectively on these plots. Therefore the yield for the test does not reflect any improvement due to the increase in zinc concentration.