Corn has a high demand for zinc, and zinc is the most common micronutrient deficiency in corn production. In addition to low soil levels of available zinc, conditions favoring zinc deficiencies are cool, wet and cloudy weather during the early growing season; high soil pH levels in all types of soils; sandy, low organic matter soils; organic soils; and high soil phosphorus levels.
However, zinc deficiencies do not occur uniformly in an entire field, but rather in spots. Zinc deficiency symptoms may also vary from field to field, depending on timing and severity of the deficiency.
Following the 4Rs (right source, right rate, right time, right place), you can cost-effectively supplement your fertilizer management program or apply zinc exactly where it will make the most impact on your yield.
Soil tests for zinc are considered among the most reliable and can be used to target deficiency zones with prescriptive application. In addition to soil tests, you can use the following information to determine specific management zones:
- How much zinc is available is important, but keep in mind how much is being removed with the crop.
- The higher the yield, the more zinc is removed.
- Sandy soils are susceptible to zinc deficiency.
- If the phosphorus-to-zinc ratio is out of balance, deficiency can occur.
- With the SIMPAS® application system, zinc can be managed at a sub-field level, as trying to apply a fixed rate to entire field is difficult to support the different zinc needs that may exist within a field.
Real-world success with prescriptively applied zinc
With the SIMPAS application system, ZINC can be applied at the exact rate you need, precisely where you need it. Nate Eitzmann, agronomist with Asmus Farm Supply, has utilized zinc application in a couple of different ways, depending on the farm and the operation.
“In one case, the operation was already variable rating some dry zinc and had sufficient levels, based on their soil samples,” Eitzmann said. “In that operation, they had some really high phosphorus levels, and they wanted to add supplemental zinc in-furrow.”
Eitzmann worked with the farmer to make prescriptions based on high phosphorus levels and used the SIMPAS application system to apply zinc prescriptively.
“The whole goal was to provide immediate supplemental zinc until the plant could access some beyond what was tied up,” he said.
In another scenario, Eitzmann did a more traditional application of zinc, applying a flat rate with an added prescription of supplemental zinc.
“Some areas got some supplemental, some areas got none on top of a flat rate,” he said. “We didn’t have to put a high rate everywhere — we did a flat rate of liquid starter fertilizer in one pass with the variable rate zinc.”
When creating the zinc prescriptions for the variable rate application, Eitzmann and his team considered if areas were what they would call “sufficient,” and then utilized the yield maps to determine crop removal and addressed that with the ZINC SmartCartridge applied with SIMPAS to make sure they were putting back in at least as much as the previous crop took out.
“That’s the beauty of this system — the ability to prescriptively apply and tailor it to each individual operation and each individual field and by management zone,” he said. “The flexibility is certainly great to be able to apply prescriptively and flat rate in one pass. Do a flat rate to get to baseline, and then a prescriptive application on top of that for areas that are more deficient in zinc. It’s pretty neat when you can do that and check both things off the list in one pass.”
To learn more, visit www.SIMPAS.com.
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