Zinc (Zn)

Zinc Micronutrients is included in the Standard Soil Test. The level of soil zinc is “insufficient” or “low” when extractable it is less than 2.0 pounds per acre and the soil pH is less than 6.1, and when extractable Micronutrients is less than 2.5 pounds per acre and the soil pH greater than 6.0. Zinc deficiency has been observed on early-planted corn during cool, wet periods, but plants usually recover as the soil dries and warms.it is routinely recommended for corn grown on  sandy soils (Soil Groups 1 and 2) when the soil pH is above 6.5. A zinc application is normally recommended for pecan unless a plant analysis indicates that zinc is not required. A zinc recommendation for peach and apple is not generally made unless a deficiency is verified by means of a leaf analysis. Both soil and plant analyses are to be used to determine if a zinc deficiency exists. When soil it is “insufficient”, it is recommended for certain crops, the treatment rate being between 3 to 5 pounds per acre.

To correct a zinc deficiency in peach, plum or nectarine trees, foliar apply either chelated zinc, following label directions, or apply at three-week intervals a solution containing 3 ounces zinc  sulfate (ZnSO4.7H2O) dissolved in 100 gallons of water. If a zinc-containing fungicide is being applied to the foliage, additional zinc as either soil or foliar applied will not be required.

In old peach orchards, zinc soil toxicity can occur following years of applying zinc-containing fungicides. Repeated use of sludge, slag, or poultry litter, all of which can contain high concentrations of zinc, may result in soil zinc toxicity. The potential for a zinc toxicity can be reduced or eliminated by liming the soil to raise the water pH above 6.0 or 6.5, the pH level normally recommended for the crop growing or to be grown.