Every year as fall arrives farmers need to determine when their fields will be ready for harvest. Many factors go into making that determination such as standability, plant maturity, plant health and grain moisture content just to name a few. For the purposes of this post, lets talk about moisture content in field corn and how that plays into a farmers harvest plan.
First off, lets start with a little background information.
There are many types of corn grown throughout the United States, including Sweet Corn, which you buy at the store or farm stand in the summer, and #2 yellow dent field corn, which is most commonly grown by farmers throughout the Midwestern ares of the nation. Sweet Corn is most commonly harvested by farmers as a produce type product in mid summer at a very high moisture content, when the kernels are tender and full of sugars, which is what makes it one of my favorite summertime foods! #2 Yellow Dent Field Corn is quite the opposite. Field Corn is harvested by farmers as a grain product in the fall months when the kernels are dry, hard, and full of starches. While Sweet Corn goes directly into the food chain as canned corn or consumed directly off the cob, field corn has thousands of uses including Livestock Feed, Corn Flours, Corn Syrups, Ethanol to fuel your cars and much much more.
As you may already know, Sweet Corn has a short shelf life. Ears left in the refrigerator or left out on the counter do not last very long. However, Field Corn has a much longer shelf life if managed correctly. The shelf life of Field Corn is largely determined by how much moisture is in the kernels themselves. The higher the moisture content is there is a greater chance of the Corn spoiling in storage. The ideal moisture content for stored Field Corn is around 14-15%. Click here to view a chart on Field Corn’s Shelf Life
So How do farmers determine if their crop is dry enough to harvest, store, or sell?
The picture below shows 2 devices we use on our farm for determining the moisture content of our grain. They work for multiple crops but for this post we will concentrate on Field Corn. For reference the moisture tester on the left is around 4 years old while the tester on the right is around 25 years old. Both are very accurate but the newer tester has a few other useful features we can discuss later.
To determine if a field is ready to harvest, we first must determine the moisture content of the grain in the field. To do so, we walk out into the field, walk down a row of corn for a few hundred feet and pick a few ears at random. For example, if the field is 80 acres in size, we will walk into around 3-4 areas in the field and pick 1-2 representative ears from each area. In the picture above, we picked 5 ears to test.
Now that we have our ears picked and the husks are removed, we break the ears in half and begin to remove the kernels, by hand, into a bucket. While the entire ears kernels will be harvested, we normally test the kernels from the middle of the ear.
After the majority of the kernels have been removed from each ear, we blend them in the bucket and remove a measured sample for our older tester to test.
Next we slowly dump the corn into the tester. This has to be done slowly to be accurate.
After we dump the corn into the tester, we wait 15 seconds then press the button in the lower right hand corner of the tester, and it gives us an accurate reading of the kernels moisture content. This test reads 15.6%. This means the field is ready to be harvested and stored directly into one of our grain bins.
The newer tester operates on the same principles as the older one does, but is a little different.
With this tester, we fill the clear container with corn and place it atop the tester before we dump it in. This clear container has a special black slide gate on the bottom of it which helps slow the amount of kernels going into the tester when opened. Much like the older tester, it has to be filled slowly to provide accurate results.
When filled, we remove the clear container and run the test. The corn we tested here has a 29.2% moisture content which was too wet to harvest at the time of this test. As you may notice, this tester also provides us with other information including test weight (how much a bushel of this corn would weigh) and what the temperature of the grain is.
To store the grain in our grain bins, we need the moisture content to be at or under 15% as a rule of thumb. Some farmers like it a little higher and some lower, but 15% is our target. There are many times we harvest corn that is above 15% moisture and have to dry the corn artificially before we can store it in our bins. Check back for an upcoming post: Farming 101: How Farmers Dry Their Corn For Storage for more information on how we dry our corn.
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