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Test Weight as a downgrading factor in 2021 Crop

During the 2021 growing season, many parts of the Canadian prairies experienced drought-like conditions1 which impacted wheat development and reduced agronomic yield.  As a result of these extremely hot and dry conditions, test weight (TWT) was one of the primary downgrading factors across all wheat classes for the 2021 harvest.   

TWT is affected by environmental factors (drought, high temperatures) that hinder plant development, disease(s) and kernel shape. Wheat kernels that are well developed have a higher density and pack together better than those that are shriveled or wrinkled which may pack poorly, resulting in gaps between kernels.  

TWT, or bushel weight2, is a measure of grain density and is indicative of grain quality but not a measurement of agronomic yield.  Wheat with a high TWT has a high proportion of plump kernels with more starch-rich endosperm than bran.  Wheat kernels with a higher percentage of endosperm result in higher flour extraction for flour millers which increases profitability at the mill level.   

Canadian wheat customers are protected by Canada’s grading system which sets a minimum TWT requirement for each grade. In previous years, customers received shipments of Canadian wheat with TWT that were higher than the minimum requirement for the grade that they purchased. In a dry and hot growing season, such as 2021, there is a possibility that customers may receive shipments with TWT that are closer to the minimum requirement. To manage this, Cereals Canada’s milling expert Norbert Cabral recommends “Millers monitor their break releases to ensure they fall within an acceptable range to achieve good extraction while monitoring flour/semolina ash content. This ensures flour/semolina quality is maintained and end-product quality is not affected on account of low TWT.” 

To learn more about the quality crop produced in Canada in 2021, go to Canadian Cereals to watch the 2021 New Crop webinar.

Farmer holding whole wheat crops

Grading 

TWT is a grading factor for Canadian wheat with specific guidelines established by the Canadian Grain Commission as part of the Official Grain Grading Guide.  (add hyperlink https://www.grainscanada.gc.ca/en/grain-quality/official-grain-grading-guide/) The minimum TWT requirements, by grade, for the commonly grown wheat classes in Western Canada are shown in Table 1. 

TWT is a grading factor for Canadian wheat with specific guidelines established by the Canadian Grain Commission as part of the Official Grain Grading Guide.  (add hyperlink https://www.grainscanada.gc.ca/en/grain-quality/official-grain-grading-guide/) The minimum TWT requirements, by grade, for commonly grown wheat classes in Western Canada are shown in Table 1.  

In Canada, TWT is also referred to as bushel weight and expressed as lb/bu. It is based on the British imperial bushel (36.37 L) and accounts for grain compaction.

Canadian Wheat Classes and Grades  

CWRS CWAD CPSR CWRW 
No. 179 (385)No. 180 (392)No. 177 (375)No. 179 (386)
No. 277 (375)No. 279 (387)No. 2 75 (365)No. 276 (370)
No. 376 (370)No. 378 (382)    No. 374 (361)
CW Feed73 (355)cNo. 475 (367)    CW Feed73 (355)c
   No. 573 (357)        

a Adapted from the Official Grain Grading Guide (2021) – Export Grade Determinant Tables (Chapter 4).

b  TWT reported as kg/hL or g/0.5L if in brackets.