By JAMES BELL
Hays Post
The 2019 winter wheat harvest was one for the books.
Heavy moisture during the spring and continuing wet conditions kept the wheat growing and maturing late, pushing harvest back more than two weeks from normal in some areas of Kansas. Those wet and cool conditions created heavier than average yields and generally happy producers.
According to the National Agricultural Statistics Service, winter wheat production is forecasted to be up 19 percent from last year, with 330 million bushels expected to be produced.
Across the state, the average yield 50 bushels per acre, up 12 bushels from last year, and some local producers are well above that average.
That production is also coming from less with a drop of 6.6 million harvested acres since last year, according to the service.
But those wet conditions have also created potentially long-term negative effects to the soil and future winter wheat crops.
The problems of soil compaction
When the silty loam in the Hays area is dry, soil compaction is unlikely — but this year was different. Across Kansas, producers have dealt with copious amounts of rain and, in western Kansas, the water that remains in the soil could create deep compaction up to 18 inches below the surface, the effects of which might not be fully realized until next year.
In short, compaction happens when the soil is compressed and the structure of the soil is disturbed.
Topsoil compaction is easier to see but much less of a problem for producers.
“You can obviously see some of this by driving through the fields,” said Augustine Obour, assistant professor of soil science at Kansas State University Agricultural Research Center.
But the deep compaction that occurs when heavy pressure is applied to wet soil is more problematic and a serious concern for long-term crop production.
“There is probability (there is) more compaction out there than a lot of farmers realize,” said Stacy Campbell, K-State Research and Extension agriculture agent. “It definitely is real, and probably some of that was happening this year.”
Sometimes it is not visible when the soil is at its maximum water-holding capacity, according to Obour.
“When it is near its full capacity, it is prone to compaction issues,” he said.
Soil moisture around Hays has been decreasing over the last 30 days, but still remains higher than normal up to a depth of almost 20 inches, while the soil in other areas of the state remains almost completely saturated.
That waterlogged soil compacts when heavy loads are applied to it and generally there is little that can be done to prevent compaction outside of staying off of the fields.
“If it is deeper than 6 inches, it can be a big issue,” Obour said. “The problem is that it affects a lot of things, particularly water movement.”
With the no-till crop production that is commonly used in the area, soil compaction may be compounded as no-till fields hold more water because of increased biological matter in the soil that retains more moisture.
Generally, Obour said, those no-till practices are good, but in years with heavy rain, it means producers have to wait longer to avoid compaction risks.
“In my experience, it takes about one more week for our no-tills to dry compared to our traditional till plots,” he said.
It also makes compaction harder to remedy.
“If you get compaction in the no-till field, then it is more difficult to correct because you do not want to till those fields,” Obour said.
Tilling a field that has been developed as no-till will damage the soil structure, he said.
Outside of water flow concerns, once soil is compacted the inability of water to flow properly can impact soil nutrient rates.
Producers will commonly use seed treated with nitrogen fertilizer, but once the soil structure is disturbed through compaction, the nitrogen might not go where it needs to for ideal crop growth.
“With all of the rain that we have gotten, nitrogen does not hold in the soil, it moves, so there will be some leaching of nitrogen fertilizer,” Obour said.
To combat nitrogen loss, he recommends producers sample up to 24 inches to get a good nitrogen profile.
“This year, if you do that with all the rain, I’m afraid it may not be there,” he said.
In order to combat nitrogen loss, producers will often spray fertilizer on the crop, but with heavy rains, this could cause another problem — runoff that spreads the fertilizer into other areas, including waterways.
“It’s very unusual in this environment, but it’s possible this year you may have some of those issues,” Obour said.
Soil compaction can also impact the root system of crops.
“About any of the crops that we produce here, they can get rooted down several feet,” Campbell said. “So if you have compaction at 18 inches, those roots if they hit that compaction layer may not be able to get through that.”
“It can take more than five years to have this corrected,” Obour said.
Producers have options for prevention
Avoiding putting significant pressure on damp soil is the best remedy for issues associated with deep soil compaction, meaning for producers sometimes a difficult choice has to be made; harvest a damp field and risk compaction, or push harvest past the ideal time.
“The bottom line is you have to consider the implications of soil compaction to justify field operations,” Obour said.
It the equipment is light, it may only create surface compaction in the top few inches, but if it is heavy equipment, such as trucks in a loading area, then the high pressure can create deep compaction.
“Iowa State did some work on this and they found that regardless of (design) … once you have about 10 tons per axle of weight and if the soil is wet enough or fairly moist, it can cause deep compaction,” Campbell said.
A report in 2017 by DeAnn Presley, K-State soil management specialist, found a full grain cart can carry more than 17 tons per axle.
An empty combine can weigh over 15 tons as well, pushing into the danger zone of per axle weight when fully loaded.
“The machinery just keeps getting bigger,” Campbell said.
Before producers move equipment into fields they have options to help determine if they are at risk of deep soil compaction.
Obour said pressing soil into a ribbon can help determine the moisture content. If the ribbon does not break apart at a length of 3 inches compaction is a risk, if it is under 2 inches when breaking apart it the risk is lower.
He said producers can also use the K-State mesonet to check soil moisture levels.
Producers can also take steps if they must enter a field that has high moisture to reduce the risk.
“Two key points for minimizing compaction from heavy axle loads are to limit traffic when fields are wet, and to confine the majority of traffic to end rows when possible,” Presley said in the report. “Keep in mind that the first wheel pass causes 70 to 90 percent of the total soil compaction, so preventing random, unnecessary traffic routes on the field is very beneficial.”
While the risk of compaction this year is high, Obour said he believes most producers around Ellis County know of the risk and he has not heard of any issues so far this year.
A government program is also working with producers that could not work fields due to high moisture content.
The Natural Resources Conservation Service has offered an Environmental Quality Incentives Program that helps producers plant cover crops that will help retain nutrient loads in the soil and prevent soil erosion.
“Cover crops help farmers to manage soil erosion, weeds and pests and to improve soil health,” said Karen Woodrich, NRCS state conservationist in Kansas in a news release for the program. “They can also help your soil health recover after a flood or a long period of remaining wet.”
The application deadline is July 26. Producers interested in the program can call the local NRCS office at 785-625-3081.