COLUMBIA, Mo. — At the 2019 University of Missouri Crop Management Conference in Columbia, MU agronomist Peter Scharf talked about nitrogen applications in corn and some of the decisions weather challenges present for farmers.
Scharf analyzed rainfall data for the central U.S. going back to 1900, looking at the area that received more than or equal to 40 centimeters (about 15.7 inches) of rain from April through June. His research showed an increase in wet areas in the central U.S. starting around 1980.
“Just in the 25 years that I’ve been here, I’d say the frequency of wet years with yellow corn has gone up,” he said. “And the statistics are pretty strong that it’s gone up.”
The average wet area is defined by a rainfall total that is twice as big as 40 years ago, Scharf said.
The trend of wetter springs can mean losing more nitrogen, or just having more limited options for nitrogen application and timing.
Looking at data going back to 1977, Scharf said it is taking longer for farmers to get from 25% complete planting corn to 75%. There is about a 2% average increase in time statewide, but the northern three crop reporting districts in Missouri are seeing increases of 5, 6 and 4% in the time it takes them to get from 25% to 75% finished with corn planting. Scharf said farming operations are bigger, but equipment is also bigger and more efficient, so weather is probably a big part of the delay.
“The answer is there’s more days that they can’t plant,” he said.
With more acres to cover and the challenges of rain in the spring, Scharf said more producers are opting for fall anhydrous applications.
“It’s been a response to farms getting bigger,” he said. “It’s something you can do in the fall, and it makes your logistics in the spring better.”
However, a farming operation’s logistics can become dependent on applying in the fall, and some years the weather doesn’t cooperate with that. The fall of 2018 and the spring of 2019 did not make it easy to apply anhydrous.
This spring, it was hard to balance trying to get nitrogen on and get corn planted.
“They couldn’t do it all,” Scharf said.
Overall, he said farmers should work as fast as they can to get nitrogen applied, but when a field is ready to plant, that should be the top priority.
“On average, delaying planting six weeks will hurt more than delaying nitrogen six weeks,” he said.
This April was a decent month for corn planting progress in parts of the state, but then May through early June saw unusually wet conditions.
“We lost about 10 days (in the field) in May and early June,” Scharf said.
That was during about a 30-day period. On average, that part of the year has about 18 days suitable for field work, but in 2019 there were only eight days during that time.
Scharf estimated that about 50% of Missouri’s corn was planted in April, 10% in May and 40% in June. He said spring anhydrous applications worked great, but they made sense only if producers had enough operators to be applying anhydrous and planting at the same time.
This year’s weather led to more post-emergence applications of urea than normal, which Scharf said was a “good response to what we faced this year.”
Nitrogen loss this year was a lot less than in 2015, another wet year with a lot of unplanted fields. Scharf said this was in part due to later applications of nitrogen and less rain going into the soil and more running off into creeks. From April 29 through June 30, Scharf says most of the rain came from 2-inch or more rain events. Most was runoff rather than soaking into the soil, meaning less impact on nitrogen.
He also reminded those in attendance that even sidedress applications of nitrogen can be lost in certain conditions.
“Even at knee-high, which is a pretty late sidedress, it can be lost,” he said.
Scharf said later “rescue” applications of nitrogen can be a benefit in wet years with a lot of nitrogen loss.
“Getting more nitrogen on is a paying proposition if the corn needs it,” he said.