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  • Kraig Roozeboom

    Kraig Roozeboom
August 24, 2010

Saturated soils and extreme heat cause corn production problems

by Doug Toburen CNHI

Parson, Kansas — An incredibly wet spring and unbearably hot summer have been enough to weigh heavily on area corn growers.

But corn growers aren’t the only thing the weather has taken its toll on—area corn fields have also been affected, according to Kraig Roozeboom, K-State cropping systems specialist.

“A lot of corn growers got corn in the ground, got it wet, replanted it, got it wet again and replanted it again this year,” he told producers at the recent K-State East Central Kansas Experiment Field Fall Field Day held near Ottawa, Kan.

According to him, with the weather and weather-related replantings, there are problems out there — and there’s not much that can be done about some of them.

“In order for seed to grow we need three things — water, suitable weather and oxygen,” he said.

The problem producers saw this year in corn fields, according to him, was too much of one, the water, and not enough of the other two things.

“Oxygen is required for germination and emergence. However, when the ground is saturated, or standing in water, no oxygen is getting to the seed,” Roozeboom explained.

As that seed continues to lie in the ground, completely saturated and not getting any oxygen, it rots — thus, the need to replant.

Seed rot, however is not the only issue that saturated soils and lack of oxygen cause.

“Wet soils are also very susceptible to nitrogen loss, through volatilization, leaching and denitrification,” he explained.

Volatilization occurs when urea on surface residues hydrolyze, releasing nitrogen as free ammonia.

“The problem with volatilization is that the fertilizer never got through the surface so the plant could use it,” Roozeboom explained. “This could be due to surface residue but, in most cases, the soil was so saturated the nitrogen couldn’t move through it.”

According to him, leaching is when nitrate, NO3, moves with water.

“Leaching has also been an issue this year,” he said.

As if volatilization and leaching weren’t enough to deal with, the very wet spring also had corn growers dealing with denitrification.

“This is the conversion of nitrate to nitric oxide, nitrous oxide, or elemental N2, which is lost to the atmosphere,” Roozeboom said.

In short, according to him, due to the saturated soil, a lot of nitrogen this year was converted to a gaseous form and lost.

“A lot of bad things happen to nitrogen when it stays wet,” he explained.

Unfortunately, as producers found out this year, bad things don’t only happen to nitrogen and to seed when soils stay wet.

Wet soils, according to Roozeboom, also inhibit root growth.

“Roots need oxygen to survive, therefore, roots don’t grow well in saturated soils,” he explained. “Inhibited root growth may cause transient nutrient deficiencies.”

Another way root growth is inhibited is related to compaction, according to Roozeboom.

Fortunately, not everyone had saturated fields, or, if they did, they were able to replant and get a decent stand.

Then the extremely hot temperatures of summer arrived.

“In most cases heat is not a problem for corn since it is a heat-driven plant,” Roozeboom said. “

This year, however, he said, excessive heat has definitely taken its toll on corn, especially, if it was replanted.

“A lot of corn was planted late,” he said. “When you plant corn in June you are going to take some yield hits, and weather plays a big role in that.”

His advice to producers: In years like this, if there are other crop options, he would strongly look into them.

This summer, according to Roozeboom, there were so many hot days that the increased heat units in corn plants pushed the plant to maturity and grain fill early.

“The hot temperatures moved the plant to maturity so fast that yields will likely take a hit,” he concluded.

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