Increase seeding rates, phosphorus application to maximize yield potential for later wheat planting

Posted October 1, 2020

With a big cool down in temperature and no rain in the forecast, wheat planting is off to the races. Over the last 20 years, roughly half of the Kansas wheat crop is planted before October 4, according to historical data from the U.S. Department of Agriculture's National Agricultural Statistics Service (USDA's NASS). Farmers planting wheat after this date can still maximize yield potential, however, by increasing seeding rates and applying in-row phosphorus. 

"If we consider what makes an optimal planting date, we think of how the planting date is going to affect the environment in which the crop is going to be exposed," said Dr. Romulo Lollato, wheat production specialist with K-State Research and Extension. "If you plant too early or too late, we put those critical development phases of the crop into different environmental conditions." 

Lollato and the team at K-State looked at roughly 20 years of variety trial data across Kansas and neighboring states to identify the perfect time periods to plant wheat. Depending on the geographic location, the optimum window for sowing wheat can range from September 10 to 30 in the northwest to October 5 to 20 in the southwest. This gradient in sowing dates is a function of temperature, with higher elevations in the northwest seeing cooler air and soil temperatures earlier in the year. 

Optimum planting dates for winter wheat according to geographical location within Kansas. Figure adapted from KSRE publication L-818, Kansas Crop Planting Guide.

Optimum planting dates for winter wheat according to geographical location within Kansas. Figure adapted from KSRE publication L-818, Kansas Crop Planting Guide.

Planting later than these optimum windows puts the wheat crop at a disadvantage from the very start. Colder temperatures in October and November do not provide the plant enough time to establish a good stand. Specifically, later planting dates negatively impact the number of tillers the wheat crop can put out in the fall and the yield potential for those tillers. 

"If we plant too late, we're going to delay every developmental stage of that crop, including grain fill, into later in the year, pushing into hotter temperatures," Lollato said. "Those hot temperatures can really decrease our grain yield."

For every day in planting delays past early October, Lollato reported a penalty of three to four bushels of lost yield potential in northwest Kansas. Southwest Kansas had a lower penalty, but still can see one to two bushels lost per day. 

All is not lost if farmers still have wheat to plant after the optimal window. By increasing seeding rates and applying phosphorus, producers can support the establishment of the good stand needed to maximize yield potential come next summer. 

"If we are planting late, we are giving the crop less time to tiller during the fall, so the yield of that crop is going to depend more on those primary tillers," Lollato said. "So we need more of those plants out there to ensure good yield potential." 

Lollato recommends producers should bump up seeding rates by 10 percent for every week that wheat planting is delayed. Putting down phosphorus fertilizer in-row will also help boost tillering. 

"Giving the crop greater chances to put enough tillers out there is usually money in the bank," Lollato said. "If you are delaying planting, that extra phosphorus is going to help that plant get off to a good start." 

For more information, read K-State's Agronomy eUpdate: Optimum sowing dates and seeding rates for wheat in Kansas.

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Written by Julia Debes for Kansas Wheat