With adaptations perfect for the wild, dry prairies of the West, hard red winter wheat has been a clear choice for the majority of Kansas and Oklahoma, but in the wet conditions that permeate southeast Kansas, soft wheat is a rising star.
At the Crops and Coffee production meetings hosted by the Wildcat Extension District and Cherokee County Extension, Kansas State University wheat specialist Romulo Lollato spoke about the differences between soft and hard wheat production in this corner of the state.
Although difficult to distinguish with the naked eye, soft and hard wheat varieties have a few key differences that determine their production and end uses.
“Molecules of starch, gluten, protein and cell walls are bound very tight together to make a hard kernel texture in hard red winter wheat varieties,” Lollato said. “When the kernels go through a mill, because they are bound so tightly, it actually breaks those molecules and makes a coarse flour.”
Hard red winter wheat is typically broken down for use in coarse breads and hard rolls and contains a higher protein level. Soft wheat is broken down into a finer flour to be used in cookies, crackers and cakes.
“Soft wheat varieties have a softer kernel texture because the molecules are not bound as tightly,” Lollato said. “Whenever they go through the mill, the kernels will have a lot of intact starch granules that makes a finer flour.”
Across the United States, hard red winter wheat dominates soft winter wheat in acreage produced at 23 million acres for hard and 6 million acres for soft. On average, the hard winter wheat fields produced 40 bushels per acre in contrast to 63 bushels per acre for soft wheat.
“There is actually a much greater increasing grain yield for the soft winter wheat varieties in the United States as compared to the hard varieties,” Lollato said. “Yields for hard varieties have been increasing about 0.3 bushels per acre per year since 1940, and soft wheat varieties have increased about 0.7 over the same time.”
While soft wheat varieties produce impressive yield numbers compared to hard varieties, Lollato said a wide variety of factors contribute to the yield differences. Soft wheat is typically grown in areas with more rainfall, more intensive management and a longer history with breeding.
Lollato said some nationwide advantages for soft wheat varieties would include yield potential, genetic resistance to a different spectrum of insects and diseases, and tolerance to acidic soils. Lower protein percentages, lower test weight, reduced winter hardiness, and sensitivity to drought and heat would be some distinct disadvantages for soft wheat varieties, especially when grown in the West.
Southeast Kansas Specifics
The Southeast Experiment Station in Parsons has been conducting research on soft and hard wheat varieties for many years, with side-by-side trials for over 40 varieties with 3,000 scientific observations.
The trials determined excessive moisture to be a more common production problem than drought stress. Hard red winter wheat varieties in the trials average close to 50 bushels per acre where soft winter wheat varieties averaged around 58 bushels per acre, which increased significantly in years with a high-yield environment.
For both variety types, yields decreased in years with too much moisture, high temperatures at grain filling and a low amount of radiation just before anthesis.
Soft wheat varieties performed best in years with more precipitation in the 30 days leading up to grain fill. Hard wheat varieties performed best in years with a lower temperature prior to heading and needed more sunlight overall than soft wheat varieties.
“For both classes, the period just before flowering needed some more rainfall,” Lollato said. “We needed more than 1.5 inches of rainfall in that 30-day period before flowering to benefit both classes of wheat.”
A low grain filling temperature was beneficial for both classes of wheat, but a higher average temperature over the growing season saw the best yield results in both classes of wheat.
“One of the findings that was most interesting to me was that a high minimum growing season temperature benefited both soft and hard wheat,” Lollato said. “I think the average reflects a warmer winter temperature, which means the crop would go into green-up earlier and the entire cycle would be a few days ahead of schedule, helping grain filling avoid higher temperatures later on.”
The trials saw a consistent 5 to 8 bushel-per-acre yield advantage for soft wheat over hard wheat varieties with a 15 to 20 bushel-per-acre advantage in high yielding environments.
“There is a very consistent yield advantage for the soft wheat varieties compared to the hard wheat varieties,” Lollato said. “For high yielding environments above 60 bushels per acre, the difference in yield between hard and soft varieties was even greater.”
Hard wheat varieties found their advantage in the test weight and protein percentage arena, he said.
“For test weight, hard wheat varieties had an advantage of around 1 pound per bushel more than the soft wheat varieties,” Lollato said.
Soft wheat’s improved yield is proven both in southeast Kansas and throughout the United States, but understanding the reasons behind the increased yield can help producers with their decisions on which wheat is right for their operations.
“Soft wheat varieties yielded higher because they were able to capitalize when the conditions were good and they were stable in a very wet environment,” Lollato said. “Also, the lower protein content allows soft wheat varieties to yield higher.”
Protein is a high cost molecule for the wheat plant to produce where starch is a much cheaper molecule to manufacture. Overall, it costs wheat 1.6 bushels of sugar than it produces over the season to produce 1 bushel of protein.
“Soft wheat only spent 1.9 bushels of the sugar it produces to produce all of its yield — around 55 bushels per acre,” Lollato said. “Hard wheat spent about 11 bushels of sugars to produce a yield of around 48 bushels per acre.”
Hard wheat varieties have a significantly lower yield due to a much higher cost to the plant to produce because of protein percentage. The plants themselves are less efficient at converting resources into grain because of the focus on higher protein.
Some of the differences in yield can also be attributed to the history of wheat breeding programs and the genetic advancements soft wheat breeding programs have been able to produce.
“For hard wheat varieties, the yield gain due to breeding has been around 0.5 bushels per acre per year,” Lollato said. “For soft varieties, it has been almost double that.”
Soft wheat breeders can increase yields at a higher rate, partially because soft varieties are breeding in a higher yield environment. For hard wheat breeders focused on improving protein production, breeding for higher yields or incorporating soft varieties into a breeding program may not be viable options.
“If a breeder has an excellent variety with good yield potential and a good disease package but poor protein — if it’s a hard variety he can’t really release it,” Lollato said. “If it was a soft variety it could be released because protein percentage is not as big of a concern.”
Responsiveness is a factor indicating the yield’s response to the growing environment. High responsiveness can be both a good and bad factor depending on if yield is very responsive to a high yield environment or a low yield environment.
“Too wet environments are actually very detrimental to the hard varieties that we tested in this region,” Lollato said. “For the soft varieties we tested here, responsiveness was a very positive trait — in a good year, yields showed great increases but in a bad, very wet year, they remained stable.”
Hard varieties also showed increased responsiveness in good yield environments but ultimately, hard wheat varieties were not bred for high moisture environments and those varieties responded poorly in wet conditions.
Hard and soft wheat varieties are managed very similarly in Southeast Kansas. Lollato compared some of the recommendations from the University of Kentucky for soft wheat production to the recommendations Kansas State University typically gives for hard wheat production.
“They are recommending a slightly higher seeding rate than Kansas is — up to 1.6 million seeds per acre where we recommend up to 1.2 million seeds per acre for hard varieties,” Lollato said. “To me, I would be a little skeptical of going that high, with risks of lodging especially.”
The Kentucky recommendations also utilized a different nitrogen application approach, using a single rate approach based on stand, plant count and yield goals. Its recommendation focused on applying around 40 pounds of nitrogen in the fall and anywhere from 80 to 110 pounds in the spring.
Lollato said Kansas producers typically have a more precise approach to wheat nitrogen management based on soil testing and their projected protein percentage that he prefers over the Kentucky approach.
The final management factor difference between hard and soft wheat varieties was the application of foliar fungicides. Lollato encouraged producers to be more vigilant about head scab concerns in soft wheat varieties and to apply accordingly.