Corn yield lower than 2018, but trending up

Union photo by Andy Hallman

The 2019 corn yield in Iowa was down 4 bushels per acre than 2018, but that year was an all-time high for many farmers in the area. The average yield in southeast Iowa during the past 10 years has been 164.2 bushels per acre.
Union photo by Andy Hallman The 2019 corn yield in Iowa was down 4 bushels per acre than 2018, but that year was an all-time high for many farmers in the area. The average yield in southeast Iowa during the past 10 years has been 164.2 bushels per acre.

Corn yield in Iowa appears to be a little lower this year than last year.

That was what the United States Department of Agriculture estimated in November when it reported an average corn yield of 192 bushels per acre for corn. That is 4 bushels per acre lower than the 2018 harvest. Soybean yield was estimated to be 3 bushels per acre lower than 2018 when it 56 bushels per acre.

Southeast Iowa’s estimated yields are below the state average for both corn and soybeans. The region’s corn yield was estimated at 165 bushels per acre, and for soybeans it was 51.5 bushels per acre.

Rebecca Vittetoe, a field agronomist for Iowa State University Extension & Outreach who works in the Washington office, remarked that there were many reasons for the lower yield this past year.

“Twenty-nineteen was a challenging growing season to say the last,” Vittetoe said.

Vittetoe said the wet spring delayed planting, but that wasn’t the only problem.

“We also had drier conditions in July that put some stress on the crops, especially when the earlier planted corn was starting to pollinate,” she said. “We saw some pest issues, like gray leaf spot, corn rootworms, Japanese beetles, common and southern ruts, stalk rots, and ear rots to name some. We cannot just pinpoint [the yield] to one factor.”

Though the 2019 harvest was not great, yields have been trending up for many years as farmers have been able to get more bang for their buck from their seeds and from their land. For example, the 165 bushels per acre estimated for corn yield in southeast Iowa is still above the 10-year average of 164.2 bushels per acre. In the 10-year span from 2009-2018, Washington County posted an average corn yield of 178 bushels per acre, the most productive in the region. Henry County was right at the district average of 164.1 bushels per acre, while Jefferson County reported a yield of 154 bushels per acre.

Vittetoe said improved genetic engineering has helped increase yields, but so too has improved farming practices such as nutrient management, such as timing fertilizer application to when the crop needs it the most. Farmers have gotten better at managing pests such as diseases, weeds and insects, managing the soil, planting at the right time, knowing how close together the seeds can be planted, etc.

“Lots of different factors that go into the yield,” Vittetoe said. “The one though that we cannot control is the weather!”

In November, The Union spoke with Iowa State University Extension and Outreach farm management specialist Charles Brown, who covers southeast Iowa including Jefferson and Henry counties. He remarked that corn yields were better than expected in 2019 given the planting difficulties.

Brown said prices for corn and soybeans are “not terrific” but a little better than last year’s. He said net farm income is probably 40-50 percent below its peak in 2013.

Joshua Michel, an ISU Extension field agronomist covering southeast Iowa, said the soggy planting season meant a late planting season, and that has resulted in late-maturing corn and soybeans. Some parts of southeast Iowa got some rain this fall, and that delayed the harvest even further as some farmers had to wait until their crops were dry to take them from the field.

Early frost

“Farmers have also had to deal with an early frost that came to much of the region, and that shut down those crops from finishing their maturation,” Michel said.

There is a temperature that kills plants and prevents them from maturing. Michel said a “killing frost” for corn is 28 degrees (for a few hours). Most of the state suffered this killing frost in mid- to-late-October even before the large snowfall on Oct. 29-30, though Michel said the very bottom tier of counties in Iowa were saved from it. The significance of a corn plant failing to reach full maturity is that its kernels will be lighter and therefore not nearly as lucrative for the farmer.

Vittetoe said farmers had two weeks of good weather in April in which to plant, but if they missed that window, they had to wait until June in many cases. That led to one problem — a late harvest — which was compounded by moisture problems in the fall.

Wet crops

“The crops coming out of the field are a lot wetter than normal,” Vittetoe said. “Before the corn can go into bins, it has to dry, so that’s slowing things down. Now that we’re into November, we won’t see much drying in the field. Drying is affected by the wind, relative humidity and temperature, and the colder it is, the less drying we see.”

The Union asked Vittetoe if it’s more common for corn or beans to be harvested first. She said it depends a lot on the weather. If farmers have to dry their corn with propane gas, they might start harvesting corn, fill the dryer, and while the dryer is working, harvest beans. This is because they can only harvest corn as quickly as the dryer can dry it. Plus, beans are not normally dried with propane. Farmers usually let them dry in the field.

Brown said that because farmers had to dry their corn more than normal this year, “this harvest will be a little costlier than in past years.”

Michel said the high moisture content of the fields has been affecting beans, too, as has low test weight.

Pests and diseases

A new disease beginning to make its mark on the region is one affecting corn called tar spot. It appears to be migrating from Wisconsin into eastern Iowa and now into southeast Iowa. The disease affects the corn’s leaves, preventing them from receiving energy from the sun and thereby blocking photosynthesis, the process of converting light energy into chemical energy. That, in turn, affects how much energy the plant can put into growing its ear.

“If you’re not able to rub it off with your fingernail, there’s a good chance it could be tar spot,” Michel said. “I would recommend checking with your local agronomist to be sure.”

Vittetoe said the biggest pest for soybeans this year was the thistle caterpillar, normally a minor problem. The caterpillars hurt the soybeans by eating their leaves.

“I know some farmers had to spray for them, and mentioned that the defoliation could hurt their yields,” Vittetoe said.

Corn plants, especially those planted early in the year, had to deal with gray leaf spot. Vittetoe concurred with Michel in describing tar spot as a major problem for corn.

“It’s definitely a disease we’re going to talk with farmers about,” Vittetoe said.

Federal aid

Brown said that a large share of farm income this year will come from sources other than the sale of crops. A report from the American Farm Bureau Federation projects that 40 percent of farm income — $33 billion of a projected $88 billion — will come from trade aid, disaster assistance, the farm bill and insurance indemnities.

Since the United States and China began a series of tariffs targeted at the other country in 2018, the U.S. government has made payments to farmers as a way of compensating them for the revenue they lost from the trade war. Formally, this money is known as a Market Facilitation Program payment.

“The government looked at every county in Iowa, and calculated how much that county lost in trade to China,” Brown said. “Farmers were paid a certain dollar amount for each acre they farmed in that county. The only catch was that they had to plant the crop, and if they couldn’t plant, they wouldn’t get the money unless they planted a cover crop by Aug 1. And if they planted a cover crop, they got $15 an acre.”

Another program that has supplemented farmers’ income is the Prevented Planting Insurance, a government-subsidized insurance sold by private companies.

“The premiums that farmers would typically have to pay are around 65-70 percent of what they would otherwise have to pay [absent the subsidies],” Brown said. “Government subsidizes those premiums so farmers can afford to buy insurance, and so that the government doesn’t have to step in with ad hoc payments after a disaster.”