Production Blog

Kansas Research Puts Peas in Crop Rotation

Pamela Smith
By  Pamela Smith , Crops Technology Editor
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Peas are taking root in new regions, such as Kansas, as grower search for new rotations and ways to build nitrogen. (Photo courtesy of Kraig Roozeboom, Kansas State University)

Peas have found purpose in parts of Kansas. Trials by Kansas State University researchers are showing that adding a legume, such as field peas, may help fix nitrogen and possibly reduce synthetic nitrogen use in grass-heavy crop rotations.

Kraig Roozeboom, Kansas State University cropping systems agronomist, said typical rotations in western Kansas often do not contain broadleaf crops, such as soybeans. Instead, this region tends to lean on wheat-sorghum-fallow, wheat-corn-fallow or wheat-corn-sorghum-fallow rotations.

"Peas in this area can replace a portion of the fallow period between the last summer grain crop and the next wheat crop," Roozeboom told DTN via email.


Beau Anderson has experienced the rotational benefits of peas on his Williston, North Dakota, farm.

"A decent stand with good root nodulation will typically fix 35 to 50 lb. of N in a growing season. It varies a lot, depending on the year and is not a sure thing. But as growers continue to use pulses in rotation, they should see nitrogen fixation and organic matter slowly increase over time," said Anderson.

Anderson has been growing pulses for about 15 years and said wheat following a pulse crop is typically heavier in test weight and higher in protein because of that extra "free" nitrogen. "We've found that N is not made available in the soil until later in the next growing season," he added.

Analysis of NASS pulse acreage projections as of April can be found in this document from the USA Dry Pea & Lentil Council….


In a recent news release, Roozeboom discussed the trials he's been conducting with graduate researcher Sarah Zerger, in Colby, Hays, Scandia and Manhattan areas. Wheat after peas data looked better than wheat that followed soybeans at some eastern locations, Roozeboom noted.

The researchers picked up residual nitrogen two years after pea and soybean harvest ahead of the corn crop (that had followed the wheat crop that followed pea crop). "The same thing applies to soybeans, so peas aren't any different in that regard," he noted. What's different is that soybeans aren't typically an option in the western areas of the state, he explained.

Adding field peas to the rotation could possibly present new market opportunities for Kansans. Roozeboom said so far, most pea plantings have been in northwest Kansas, but researchers are continuing to push boundaries to see how far east the crop can be planted in the state.

Figuring out weed control could be another challenge. Roozeboom said there are several pre-and post-herbicides available -- similar to those labeled for non-GMO soybeans. Peas aren't always competitive early in the growth cycle, but he said the crop makes up for it later. "I would contend that a good stand of peas is very competitive once the canopy closes," he added.

Herbicide carryover is another potential issue. Residual activity of herbicides applied to the preceding crops needs to be considered carefully. Find a discussion about carryover here:….

Find the Kansas State University release here:….

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