When the soil biology does not provide enough calcium during rapid vegetative growth stages, cell division continues imperfectly, resulting in the common leaf ‘zippers’ on corn and other grass crops.
The location of the zipper can also indicate whether boron is inadequate. Adequate levels of boron produces the effect of moving nutrients and water through the plant and leaf quickly to the outer edges. When the zippering effect occurs at the edge of the leaf, it may indicate there is not enough boron present to move calcium to the leaf edge. When zippering occurs in the middle of the leaf, boron may be adequate, but calcium remains low.
When enough calcium is present to remove the zippering effect, plants get significant growth energy from the abundant calcium, and nitrogen requirements drop. This is one reason some farms grow high yielding, high test weight corn with only .35 – .5 lb of N per bushel measured in the system.
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