High Moisture Corn Tips From Chad Hermelbracht
We just wrapped up two great combine clinics here in Nebraska. One of the main concerns going into harvest is high moisture corn. Now feedlots deal with high moisture corn every year and it has its challenges, but why are normal grain farmers concerned as also? Well, every corn hybrid that is planted has a set maturity. Most of you will call this “x” number day corn. 115 day, 110, 95 day corn. This isn’t exactly accurate. 95 day corn isn’t absolutely ready in 95 days. It all goes back to Growing Degree Days and Heat Units. Heat Units for corn is a range in how much heat a plant absorbs during a day. This range is from 50 to 86 degrees. Anything over 86 does not help the plant any more. It is wasted heat. Likewise, under 50, we gain nothing. Last night we dipped just up the 50 degree mark and have a high of 78. Yes this feels amazing, but it is slowing the progression of the corn development. Cool days along with a late planting is what has pushed the corn so far behind. A 110 day corn is a relative number but most seed corn companies will tell you the exact heat units needed to reach black layer. For example a 110 day corn needs 2650 heat unites to reach black layer.
What is black layer? Black layer is the sign of physical maturity for the kernel of corn. A corn kernel develops as follows:
R1 Silking – this is where the ear shoots silks to capture pollen.
R2 Blister – kernels are pollinated and contain a clear fluid. Silks are drying and turning brown.
R3 Milk – kernels are starting to swell and have a white milky fluid in them.
R4 Dough – the milky fluid is starting to solidify as starch. At the end of R4 you will begin to see dents in the kernels
* We are just entering the R5 stage with this ear.
R5 Dent – Kernels are dented on the top. This is usually a sign of maturity, but note the ear is only 50% matured and still has another 30ish days before maturity. The kernel moisture is around 60% at this point.
R6 Black Layer – Black layer is when the kernel has severed the connection to the cob. There is no more movement of nutrients or water between plant and kernel. This is final maturity. Grain will average around 30% moisture at this time.
We can physically watch the grain mature between R5 and R6. This is called the milk line. At the corn shifts from the dough to final hardened starch, it works from the top down. We can see this as we observe an ear broken in half.
The left side is the tip, the right is the base.
We are not able to see a milk line yet, but as there are two sides to a coin, there are 2 sides to a kernel of corn. As we look down at the ear, the right half, the base half, shows us the embryo of the kernel. This won’t look too much different as we mature. The tip half is the one we need to concentrate on. We will see a line form and begin to work its way down to the cob itself. This is the milk line. Once that line reaches the cob, we have black layer and physical maturity.
We need to reach black layer before frost to get the highest test weights and have the best dry down. This is why farmers are concerned about high moisture corn. We are behind on heat and behind on the maturity process. Not much we can do but wait and be ready to help growers adjust their combines to best handle corn moistures higher than they normal harvest at.