As we well know, “moisture content” is an important factor when it comes time to pull the crop out of the field. Wetter grain at harvest increases the need for artificial drying, and in turn increases production costs. With low prices and a weak basis this is clearly an expense many producers are not wanting to think about. Black layer usually occurs at about 30% to 33% moisture content and depends on variety, weather, soil types, moisture, and production practices. Corn will shell with a combine at about 30% moisture content with somer kernel damage, so question becomes, when should you get ether corn out of the field? Several studies from the Midwest indicate combine losses are least when corn reaches 26% moisture (about 1 to 3 percent losses are typical). Combine losses increase as the grain moisture dries. Losses of 10% to 15% are fairly common with corn at 15 percent moisture. Midsouth growers’ believe that initial corn harvest should begin as the corn field dries to 18% to 20% moisture, where as Midwest data strongly suggest beginning harvest at 25% moisture content, based primarily on long-term weather and machine loss data. I remember hearing from a producer a couple of years back who went into his field and started harvesting corn at between 25% and 27% moisture, adjusted to dry bushels it was yielding north of +200 bushels per acre. He decided he didn’t want the huge expense of drying it all down, so he decided to jump over to harvest soybeans. There was also some early frost concerns that helped him make the decision to jump form corn to soybeans. Regardless, when he returned to finish the corn, it had dried down to about 16% just like he had hoped, but it only yielded about 185 to 190 bushels per acre. Here we are again this year. We’ve had some heavy rains and good moisture in many locations, and prices are extremely low. Our natural thoughts are to reduce expenses and let the corn sit in the field a bit longer to help dry itself down and reduce drying expenses. The question is will we be doing more harm than good? Will we lose more in yield than we save in drying expenses? There’s obviously a ton of debate about the subject, but I remember reading one study by Perdue that proved a yield loss of 0.6% to 1.6% per point of moisture can occur in corn drying in the field. From everything I hear “yield loss” can be even worse if corn dries down, then is hit again with more moisture in the field by rain and humid weather, as it can then then start sprouting which hurts overall quality, testweight and even overall yield. We could also start to see more stalk and root lodging at the combine which will create more losses. Also keep in mind it’s normally cheaper to dry corn down in late-september or early-October than mid to late-November, since you don’t have to heat up the outside air as much. the folks at SuccessfulFarming ran an interesting article a couple of years back, and estimated that If the elevator charges 3¢ per point of moisture per bushel (plus shrink), it would cost 21¢ per bushel to dry corn from 22 percent to 15 percent which is $42/acre at 200 bushel corn. At $3.25/bushel corn price it takes 13 bushels to pay for drying. It is very likely in this scenario that you could lose 10+ B.U./A. bushels per acre by letting the corn dry in the field. Further reasoning to justify harvest at 25-20 percent moisture can be made by considering adverse weather/wind/rain during this time along with the other benefits that come with a timely harvest. The University of Mississippi, says drying off 10% of grain moisture (25 to 15 percent) requires removing 7.47 pounds of water. And will require about 15,000 btu of heat in a drying system with the normal efficiencies in the Midsouth (about 2000 btu per pound of water removed). Understand, moisture content and the amount of drying required will also affect stress cracks, breakage, and germination. Extremely wet grain may be a precursor to high mold damage later in storage or transport. While the weather during the growing season affects yield, grain composition, and the development of the grain kernels, grain harvest moisture is influenced largely by crop maturation, the timing of harvest, and harvest weather conditions. General moisture storage guidelines suggest that 14% is the maximum moisture content for storage up to 6 to 12 months for good quality, clean corn under typical U.S. corn-belt conditions; and 13% or lower moisture content is recommended for storage of more than one year. I wanted to share with you the only national data I could find on average corn moisture levels over the past few harvest seasons in the U.S. This is good information that may give us an indication of the quality of this year’s crop in comparison. This data is gathered by the U.S. Grains Council and found in their post-harvest, annual Corn Harvest Quality Report 2016/17. I also included some other helpful tips. (Source: Perdue Corn Harvest Decision Tool; University of Mississippi)
Late-Maturing Fields Could Take Much Longer to Dry Down: The folks atChannel Seed report, “ideal harvest moisture content for corn is between 22 to 25 percent. Corn drydown is linked to growing degree units (GDUs). Under ideal weather conditions, corn may lose up to one point of moisture per day. As the days get cooler, GDU accumulation per day decreases and grain drying slows. As a rule of thumb, 30 GDUs per moisture content point are required to lower the grain moisture content from 30 to 25 percent and 45 GDUs per point are required from 25 to 20 percent. This means that late-maturing fields may take two to three times longer to dry in the field. Research from The Ohio State University indicated no additional in-field grain drydown occurred after early- to mid-November.
Moisture Variation With Each Ear: Within ears of corn, it’s very common for the kernels to vary in moisture content due to the amount of exposure the kernels have had to sunlight. Typically the top kernels have lower moisture, while kernels at the bottom of the ear have high moisture. The research team at IntelliFarms University found that there is approximately a 5-8% moisture variation between top and bottom kernels in ears of corn.
Be Careful Not To Lose Yield: The folks at Pioneer report, “a bushel of corn is traded on the basis of 56 lbs. per bushel. A bushel of corn at 15.5% moisture contains 47.32 lbs. of dry matter and 8.68 lbs. of water. This is an important concept to remember because as corn becomes drier you are actually delivering more dry matter to the market and less water weight. While delivering bushels to the market at optimum moisture is important, it is only one of the factors determining moisture levels of corn going into storage. Overdrying corn can lead to significant dollars lost due to added expense and less bushels to sell in the market. At 15.5% moisture and a market price of $3, a bushel of corn is worth 6.34 cents per lb. of dry matter. This same corn at $5 per bushel is worth 10.57 cents per lb. of dry matter. If your goal is to store and market corn at 14.5% moisture and it is inadvertently dried 1 point less (13.5%) you have given up 3.8 cents/bu in today’s market (corn at $3.25 /bu). The drying cost for the extra point would be 0.02 gallons of propane. In other words, it takes about 0.02 gallons of propane to remove 1 point of moisture per bushel of corn.”
Field Drying vs. Bin Drying: Our friends at Wyffels Hybrids report, “Grain drydown on wet, cool days will be 0 to 0.3 percent moisture loss per day. On the other hand, moisture loss can be as high as 1 percent on hot, dry days. Grain drydown rates this year should range from 0.4 to 0.6 percent per day. However, corn that doesn’t reach black layer until late September or early October will have slower dry down. They include a few things to consider when deciding to harvest or leave in the field to dry down: Harvest loss of lodged corn can be high, and will increase the longer the corn is left in the field. Plan to harvest these fields as soon as possible; Each ¾ pound ear in 1/100th of an acre represents a loss of 1 bu/Ac. Consider the high number of unharvestable ears in a lodged field; Two lost kernels per square foot equals a loss of 1 bu/Ac. Properly adjusted combines can pay big dividend; An Iowa State survey indicated that the average mechanical harvest loss was 5.8%; Mechanical harvest loss increases as corn dries below 25%. One study demonstrated harvest losses increasing from 3.6% for 25% moisture corn to 12.3% for 17% moisture corn. Fields with poor stalk quality are at a higher risk of harvest loss. And the risk increases the longer harvest is delayed. Plan to harvest these fields as soon as possible.
Average U.S. aggregate moisture content recorded at the elevator in 2016 samples was 16.1%, which was higher than 2015 (15.7%), lower than 2014 (16.6%), and the same as 5YA (16.1%).
Gulf corn moisture was reported to average 16.2%, which was slightly higher than corn leaving the Pacific Northwest at 15.9%, and the Southern Rail at 15.7%. Average moisture levels for the Gulf ECA were highest or tied for highest among all ECAs for 2016, 2015, 2014, and 5YA. Samples from the Gulf usually contain higher moisture content values as a result of weather and harvest conditions.
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