Posted: Monday, March 18, 2013 10:24 AM
By MATTHEW WEAVER
Researchers are examining the relationship between protein levels in wheat and low scores in the falling number test.
The test measures wheat quality, particularly in the event of sprout damage.
The falling number test involves grinding a small sample of wheat and mixing it with water to create a paste. When placed in boiling water, the paste thickens. If the enzyme alpha amylase -- associated with sprout damage -- is present, it begins to consume the starch, reducing the thickness.
A small, weighted plunger is placed in the paste and timed as it "falls" through the paste. The test measures the time it takes for the plunger to fall, plus a 60-second initial stirring.
The industry standard for soft white wheat is 300, meaning it takes 300 seconds for the plunger to fall. Numbers below that generally indicate lower quality wheat that could present processing problems. Farmers are docked if the ratio of problem wheat to good quality wheat is too high.
State and federal grain grading laboratories managed by the USDA Federal Grain Inspection Service typically conduct the test. The grain is delivered to the elevator, then submitted to the lab.
"The lower the grain protein you have, typically the lower the falling number you have," Mike Flowers, cereals extension specialist at Oregon State University, said.
Fertility and yield potential impact protein. The higher the yield and the more starch in the kernels, the lower the protein, Flowers said. To counteract the effect, farmers apply more nitrogen fertilizer to increase protein.
Wheat with about 8 percent protein can have falling number problems, Flowers said.
In eastern Oregon and Washington, protein is likely to be in the 9-10 percent range, so it's less of a concern, Flowers said.
Flowers worries about protein levels in the Willamette Valley, where proteins are consistently 8-9 percent and at a higher risk for low falling numbers and pre-harvest sprout.
"Some of this data is going to be very useful to help us determine management changes we need to make," he said. "Maybe we need to adjust our nitrogen rates so we can get a little bit higher proteins."
There's only two years of data so far, and Flowers expects to continue to gather more information.
If the weather continues to be cold and wet and yields are higher than average, that could be a recipe for low falling numbers, Flowers said. It's too early in the season to tell how prevalent falling number problems will be, he said.
In the past, Washington and Idaho wheat industry members have called for a revisit of the test, questioning its accuracy since the test cannot always be replicated.
"Right now, that's the test we have to work with and that's the one we need to gear ourselves towards," Flowers said. "When (a new test) comes on board, we'll be looking at that as well."