Well, the last time we had significant Falling Numbers (FN) in the spring wheat, was during the harvest of 2019. While the FN values for this year’s 2024 wheat
crop will be better on average, we should take the time again to review why FN numbers are important and how to accurately blend various lots of FN grain to enhance grain value for the seller as well as the buyer.
The FN measurement is actually an indirect analysis of the alpha-amylase activity. Wheat grain with high alpha-amylase activity (a low FN value), will have quicker starch degradation resulting in more of a clear and watery bread dough mixture that will not produce a quality loaf during the baking - see diagram picture below. The measurement is actually done in seconds - the time it takes a stirrer to fall through the bread dough mixture.
Blending low FN wheat is not a simple and straightforward calculation, but it's not rocket science either. The target for blending by a wheat producer should be a FN
value of 300 seconds (or slightly higher) to ensure a quality product and no discounts at the
terminal.
A simple three-part equation has been created and published
for determining blend volume by the USDA and Federal Grain Inspection Service
(see link below).
Equations and example:
The first step: calculate a LN (Liquefaction Number) from
each separate lot of grain.
LN = 6000 / (FN-50)
Second step: average the LN numbers from the two, three or
more different lots of grain that will be blended together.
Third step: use this equation to calculate the new FN number
of an equal blend of the various lots.
New blended FN = (6000 /LN avg) + 50
To confirm we are all on the same page, here is an example…
assume we have two bins (lots) of equal volume.
One with a very high FN number of 400 (LN = 17.1) and one with a poor FN
number of 220 (LN=35.3). The average LN
between the two lots would be 26.2, and thus the new FN from a 50:50 mix of the
two lots would only equate to 279 (not the simple average of 310). The lower the FN score from a single seed lot, the larger amount of good quality wheat will be required to bring the FN score into an acceptable range.
In this example, it’ll take a mix ratio of about 62:38 to
hit a blended FN number of 300, (target LN avg number of 24.0). Wheat grain moisture content is assumed at
14%. There is an equation in Sec. 11 of
USDA’s document (pg. 14) adjusting for moisture.
Good luck!
USDA: Section 11 “Averaging sublots” pg. 13-15. https://www.ams.usda.gov/sites/default/files/media/FGIS9180_38.pdf
NDSU Crop and Pest Report: https://www.ag.ndsu.edu/cpr/plant-science/low-falling-numbers-in-wheat-a-concern-08-29-19
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