Black Layer

This corn has now reached "black layer." In this picture a few weeks ago which seems like a few days ago, it hadn't.

"When agronomists talk about black layer in corn what does it mean? Black layer refers to the point in time when dry matter accumulation in the kernel ceases. It is also occurs when the milk line has receded all the way to the base of the kernel. At this moment the kernel no longer get any heavier or bigger regardless of the weather.

In corn, black layer signifies physiological maturity. Physiological maturity occurs with the formation of a physical black layer located at the base of a kernel. Black layer normally occurs about 60 days after silking or 20 days after denting begins.

A dark abscission layer forms when the hard starch layer reaches the kernel base. This abscission layer cuts off water and dry matter movement into the kernel. Kernels will have a moisture content of about 30 to 35 percent at this stage. From that point on corn will dry down a half a point a day to acceptable harvest moisture. So if grain is at 30 to 32 % at black layer it requires another 30 days to drop to 15.5 percent.

The black layer can be seen by shelling kernels and scraping away the seed coat to expose the black abscission layer. The black layer formation occurs progressively from kernels at the tip of the ear to the base.When agronomists talk about black layer in corn what does it mean? Black layer refers to the point in time when dry matter accumulation in the kernel ceases. It is also occurs when the milk line has receded all the way to the base of the kernel. At this moment the kernel no longer get any heavier or bigger regardless of the weather.

In corn, black layer signifies physiological maturity. Physiological maturity occurs with the formation of a physical black layer located at the base of a kernel. Black layer normally occurs about 60 days after silking or 20 days after denting begins. A dark abscission layer forms when the hard starch layer reaches the kernel base. This abscission layer cuts off water and dry matter movement into the kernel. Kernels will have a moisture content of about 30 to 35 percent at this stage.

From that point on corn will dry down a half a point a day to acceptable harvest moisture. So if grain is at 30 to 32 % at black layer it requires another 30 days to drop to 15.5 percent The black layer can be seen by shelling kernels and scraping away the seed coat to expose the black abscission layer. The black layer formation occurs progressively from kernels at the tip of the ear to the base.' (Daniel Davidson, DTN)

You can see why this is so important for sileage corn or anyone who irrigates corn. If you are chopping sileage, the plant is going to die after black layer and the kernal starts drying down. If you are irrigating corn, all you are going to do is keep the plant green but not change the grain yield.

My corn is physilogically mature so it has begun dry down. My yield is there, what moisture do I want to harvest it? I could start shelling my corn and mechanically drying but I and most farmers will let Mother Nature dry it down for me and save the cost. My grain is still probably over 26% moisture and the market pays for 15%, not the water above that amount.

Corn shells well at 20-21% moisture or lower without much mechanical damage to the grain so we have a few weeks yet. Still some farmers are shelling from the south all the way up into Illinois. Steve Terpstra at Mark Seed sent me two results from Illinois yesterday, one was 130-140 but and the other lucky fellow reported 207 bu dry on a field of 107 day corn.

I don't know who came up with the term black layer but I have heard it and the term milk line in corn all my life. It sounds strange to anyone who doesn't deal with corn.

Ed