Imagine strolling through a cornfield in early to mid-September, filled with anticipation. You carefully peel back the husks of an ear, split it in half, and pluck out a kernel. With your pocketknife in hand, you examine the tip, searching for a remarkable phenomenon – the black layer.
For Dave Nanda, director of genetics for Seed Genetics Direct, finding the black layer is like discovering buried treasure. This thin layer signifies that the kernel is fully mature and safe from the threat of frost. It’s an incredible feat accomplished by the corn plant, unknowingly producing viable kernels that won’t be planted.
Reaching the black layer is not only significant for the corn plant but also for growers. While frost damage may not be a concern every year, it can make a difference, especially in late-planted fields. Just two years ago, in 2019, late-planted fields struggled to reach the black layer until early to mid-October, causing concern among many farmers.
The Intricacies of the Black Layer and Moisture
Although the black layer indicates maturity, it doesn’t necessarily mean the kernels are dry enough for harvest. The moisture content at the black layer stage can range from 25% to 40%, depending on when you prefer to begin harvesting. As per Dave Nanda’s observations, the moisture typically falls within the 30% to 35% range when the black layer forms.
According to the Purdue University Corn & Soybean Field Guide, physiological maturity occurs 55 to 65 days after the R1 stage commences. It is at this stage that the kernel dry weight reaches its maximum, and the milk line disappears. Finally, the black layer forms, as a layer of cells die, collapse, and seal the end of the kernel.
Once the black layer is formed, the kernel’s weight and starch content reach their peak. Interestingly, nothing can enter or exit the kernel after this point. Even if the plant faces severe stress, the yield won’t be affected. The only threat to yield at this stage would be insects, diseases, or a destructive windstorm compromising the stalk.
Nearing the End of the Season
Suppose you’re inspecting ears and haven’t yet come across the black layer. How long will it take for the black layer to form?
If your cornfield is in the dough stage (R4), Purdue University’s guide indicates that you would need approximately 37 calendar days or 602 growing degree days (GDDs) to reach the black layer. However, if the corn is in the dent stage (R5) with the milk line gradually moving down towards the tip, you should only require around 20 days or roughly 300 GDDs to reach the coveted black layer.
So, the next time you find yourself amidst a cornfield, keep your eyes peeled for the hidden magic of the black layer. It’s a secret shared by the corn plants and those fortunate enough to witness it. To learn more about the world of corn and experience the best of barbecue, check out Rowdy Hog Smokin BBQ. Happy corn hunting!