Row By Row / February 2017

Hit the right harvest window to minimize yield loss

Fall harvest is when corn farmers reap the rewards of their hard work. It’s also when they face major variability in environmental conditions — and potential yield loss — as they race against the clock to get the crop in the bin.

Time is of the essence during harvest, with a crop at maturity and variability in weather conditions that can range from heat and humidity to wind and snow. Making sure your crop gets harvested in optimal time takes planning, accounting for potential roadblocks from Mother Nature, and employing the right equipment, says Fenton, Iowa, farmer and Dragotec USA president Dennis Bollig.

“You have to calculate all the risks when determining the optimal harvest timeframe,” Bollig says. “There’s risk to harvesting too early, just as there’s risk to leaving a crop in the field too long. You need to weigh all the weather variables that can degrade your crop quality. Heavy rain, high winds or even a snowstorm at harvest can knock your crop down almost immediately. You have to be able to react to a lot of variables at harvest.”

Crop Moisture Issues

Shelling loss and ear bounce are common ways to lose yield at harvest during moisture extremes. It’s important to find the “sweet spot” for crop moisture at harvest.

“Delaying harvest until corn dries to 15 to 20% will save considerable artificial drying costs,” according to a report from Iowa State University Extension agronomist Roger Elmore.

Elmore says the general weather conditions immediately preceding harvest can give you a good idea of how drydown is progressing. As a rule of thumb, corn at maturity is around 30% moisture, and depending on the weather conditions, it typically takes at least two weeks to dry down to 20% moisture.

“Grain usually dries at a linear rate that varies depending on weather and other factors. For example, wet and cool weather slows drying,” Elmore says. “We’ve seen drydown rates less than 0.3% per day. On the other hand, warm, dry weather speeds drying; kernels can lose up to 1.0% moisture per day with excellent drying weather.”

Crop Deterioration Concerns

Though modern corn genetics help the crop stand better in the field longer, once it’s reached maturity, deterioration begins. And, when stalks start to deteriorate, yield loss potential grows quickly.

“Standing in the field past maturity, the crop is getting weaker by the day, and the deterioration process accelerates quickly, especially when facing weather extremes,” Bollig says. “The stalk and shank holding the ear on the stalk can weaken and cause down corn and yield loss. And the later you move into the season, the greater the loss.”

Balancing the right crop moisture levels with potential deterioration can be difficult, but it can make all the difference in minimizing yield loss, Elmore adds.

“Harvest efficiency decreases rapidly and losses increase in fields with lodged corn. As grain dries in fields after reaching black layer, monitor individual fields and hybrids for grain moisture, stalk quality and ear retention,” he says. “Schedule harvest based on these variables.”

React With The Right Equipment

Though you can typically track drydown to the optimal point at harvest, Bollig says it’s important to stay vigilant and react to sudden changes in field moisture conditions that can lead to greater crop deterioration. The exact time to harvest each field should be based on production history, weather conditions and crop varieties. But, having the right equipment can help you react to the variability and challenges common at harvest time. “If you have a corn head that does a better job of picking up down corn, adjusts to stalk variability and handles drier corn more gently, you have a better chance of widening your optimal harvest timeframe,” Bollig says. “That crop really isn’t yours until you’ve got it in the combine tank. A Drago Series II or GT corn head can help go down and get any corn that Mother Nature has mistreated leading up to harvest. You can still go get it and minimize yield loss with a Drago.”