Winterkill may be a concern for Kansas wheat growers this year.
The biggest potential for winterkill to the wheat crop is in fields that emerged in late October or afterward, where snow cover was limited to less than 2 inches; and in regions which soil temperatures reached the low teens to single digits. Those regions of greatest concern are central Kansas because of its limited snow depth, and northwest Kansas due to its extremely cold temperatures.
According to Romulo Lollato, Kansas State University Extension wheat and forage specialist, the next four to six weeks will be crucial to determine the recovery potential of the crop. “Ideally, precipitation would alleviate the current dry conditions, and temperatures would warm up slowly so that the crop can start spring development,” he writes in a recent K-State Agronomy eUpdate newsletter. “Continuation of the dry conditions can further impair crop recovery.”
Unfortunately, Lollato warns there is nothing growers can do at the moment, other than wait until green-up to evaluate the crop. “As wheat green-up progresses, any winter injury will become more apparent,” he says. “Injured wheat may initially green up, then go backwards.”
Extreme weather impact
Like many areas around the country, Kansas saw extreme cold temperatures in mid-February.
The lowest air temperatures ranged from -11 degrees F in south central Kansas to -29 degrees in north-central Kansas, reports Mary Knapp, with K-State Weather Data Library. The majority of the temperatures in northwest Kansas ranged from -18 to -26 degrees.
“These temperatures would be low enough to cause leaf burn and winterkill,” Lollato says. If soil temperatures reached these levels, they could also damage the crop.
While average soil temperatures from Feb. 10 to Feb. 17 were usually above 20 degrees, the lowest soil temperatures dropped as low as 5 to 14 degrees. Soil temperatures in the low teens or single digits occurred mostly in northwest Kansas, but they were also present in parts of southwest and central Kansas.
Soil moisture and snow cover
Two environmental factors that affect the crop’s response to cold temperatures, due to their potential of buffering low air temperatures, are soil moisture content and snow cover.
The dry spell observed in central, north-central and western Kansas prior to the cold spell also resulted in very low topsoil moisture, which did not help in buffering the lower air temperatures.
Regarding snow cover, the majority of the wheat-growing region of Kansas received from 1 to 2 inches of snow, with the extreme north and southern borders receiving up to 4 inches. However, the central portion of the state saw virtually no snowfall.
Reports suggest it was a dry, lightweight snow, decreasing its buffering potential. This decreased its buffering potential, especially compared to the totals achieved in the neighboring states of Oklahoma, where farmers saw up to 10 inches; and Nebraska, with up to 20 inches. Regions receiving 1 to 2 inches of snow probably had some buffering of the low air temperatures and may have helped in the current spell.
For example, stations where snowfall was reported had at the lowest, minimum soil temperatures of 24 to 28 degrees, versus 15 degrees reported in a neighboring station without snowfall.
Still, the combination of extremely cold air temperatures and dry soils, with a limited amount of snow across the majority of the state, might have caused damage to some fields.