Fig. 1. A standard filling hopper and also stand for the exact filling of quart or pint cups for serial test weight determination. (Image: www.seedburo.com).
Fig. 2. Corn serial test weight versus grain yield because that 27 hybrids grown in ~ 3 Kansas places (Lingenfelser et al, 2011) . Click on image come view larger version.

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Fig. 3. Corn serial test weight versus grain yield for 22 hybrids grown in ~ Greenville, five in 2012 (drought) and 2013 (ample rainfall). Click image to view larger version.
update September 2021 URL: http://www.kingcorn.org/news/timeless/TestWeight.html grain Test load Considerations for Corn R.L. (Bob) Nielsen Agronomy Dept., gimpppa.org Univ. West Lafayette, IN 47907-2054 email address: rnielsen in ~ gimpppa.org.edu Twitter:

The official minimum allowable test load in the U.S. Because that No. 1 yellow corn is 56 lbs/bu and also for No. 2 yellow corn is 54 lbs/bu (USDA-AMS (FGIS), 1996). Corn serial in the U.S. Is marketed on the basis of a 56-lb "bushel" regardless of test weight. Even though grain moisture is not component of the U.S. Standards for corn, grain buyers salary on the basis of "dry" bushels (15 come 15.5% grain moisture content) or discount the industry price come account for the drying prices they expect to incur managing wetter corn grain.

Growers worry around low check weight due to the fact that local grain buyers frequently discount their market bids for short test weight grain. In addition, growers are naturally disappointed when they provide a 1000 bushel (volumetric bushels, the is) semi-load the grain that averages 52-lb check weight since they only acquire paid for 929 56-lb "market" bushels (52,000 lbs ÷ 56 lbs/bu) plus they obtain a discounted price because that the low test load grain. ~ above the various other hand, high test load grain provides growers feel great when they provide a 1000 bushel semi-load of grain the averages 60 lb check weight due to the fact that they will gain paid because that 1071 56-lb "market" bushels (60,000 lbs ÷ 56 lbs/bu).

These emotions encourage the belief that high test weight grain (lbs that dry issue per volumetric bushel) is associated with high grain yields (lbs. The dry issue per acre) and also vice versa. However, over there is tiny evidence in the research literary works that grain test load is strongly related to grain yield.

Hybrid variability exists because that grain check weight, yet does not instantly correspond to differences in genetic yield potential. Serial test weight for a offered hybrid frequently varies from field to ar or year come year, however does not immediately correspond come the in its entirety yield level of one environment.

Similarly, grain from high yielding areas does no necessarily have greater test weight 보다 that from lower yielding fields. In fact, test load of grain harvested from severely stressed areas is occasionally greater than the of grain from non-stressed fields, as shown in Fig. 2 for 27 corn hybrids grown at 3 locations with widely varying yield level in Kansas in 2011. One more example from Ohio through 22 hybrids get an impression in common in the dryness year the 2012 and the much far better yielding year the 2013 also indicated no relationship between yield level and also grain test load (Fig. 3).

Conventional dogma says that low test weight corn grain decreases the processing efficiency and quality of handle end-use assets like corn starch (U.S. Grains Council, 2020), return the research literary works does not repeatedly support this id (Yang et al., 2000). Similarly, short test corn grain is often thought come be inferior for pet feed quality, return again the research literary works does not assistance this id (Laborie, 2019; Rusche, 2020; Simpson, 2000; Wiechenthal Pas et al., 1998). Whether or not low test weight grain is worse to higher test weight grain may depend on the reason of the short test load in the very first place.

Common reasons of short Grain Test weight

The 2009 corn harvest season in Indiana (late chop maturation, late harvest) was an example of one where there were an ext reports of low test load corn serial than an excellent or above average check weights. Over there were mostly six determinants that accounting for many of the low test load grain in 2009 and four common a typical overarching effect.

Grain Moisture

First and foremost, growers should understand that test weight and also grain moisture space inversely related. The higher the grain moisture, the lower the test weight AT THAT point IN TIME. Together grain dries in the ar or in the dryer, test weight naturally increases as long as kernel integrity continues to be intact. Check weight rises as grain dries partly due to the fact that kernel volume often tends to shrink with drying and also so more kernels pack right into a volume bushel and also partly due to the fact that drier serial is slicker which often tends to encourage kernels to pack much more tightly in a volume bushel. Thus in a year favor 2009 with many of the early stage harvest reports of serial moisture ranging from 25 to 30% instead of the usual starting moisture levels of about 20 come 23%, it should not it is in surprising the test weights were reduced than expected.

Hellevang (1995) available a straightforward formula because that estimating the increase in test weight with grain drying. In its simplest form, the equation is (A / B) x C; wherein A = 100 - dried moisture content, B = 100 - wet moisture content, and C = test weight at wet moisture content. The writer does no say, yet I doubt this simple formula is many applicable in ~ a "normal" variety of harvest moistures; approximately moistures in the mid- to high 20"s.

Example: dry moisture = 15%, Wet moisture = 25%, Test load at 25% = 52 lbs/bu.

Estimated test weight at 15% humidity = ((100 - 15) / (100 - 25)) x 52 = (85/75) x 52 = 58.9 lbs/bu

An older referral (Hall & Hill, 1974) provides an alternate suggestion because that adjusting test weight for harvest moisture that also accounts for the level that kernel damage in the harvested grain (Table 1). The table worths are based upon the premise that kernel damages itself lowers test weight to start with and also that more drying that damaged grain outcomes in less of boost in test weight that what occurs in undamaged grain. Compared to the outcomes from making use of Hellevang"s an easy formula, adjustments to test weight making use of these tabular values often tend to an outcome in smaller sized adjustments to test load for high humidity grain at harvest, yet larger adjustments for drier grain in ~ harvest.


Stress during Grain Fill

Secondly, thirdly, and also fourthly; drought stress, late-season foliar leaf diseases (primarily gray leaf spot and northern corn sheet blight), and below normal temperatures throughout September that 2009 all brought about a far-reaching deterioration of the crop"s photosynthesis machinery start in at an early stage to mid-September that "pulled the rug out from beneath" the successful completion the the serial filling period in part fields; leading to less 보다 optimum starch deposition in the kernels. Fifthly, early on October frost/freeze damage to late-developing, immature areas resulted in leaf or whole plant fatality that successfully put an finish to the grain-filling process with the same an unfavorable effect on check weight.

Ear Rots

Finally, ear rots (diplodia, gibberella, etc.) were widespread throughout many areas of Indiana in 2009. Kernel damage by this fungal pathogens results in light-weight, chaffy grain that likewise results in short test weight diseased grain, damaged kernels, and excessive levels of foreign material. This cause of low test load grain obviously outcomes in inferior (if not toxic) pet feed high quality grain, unacceptable end-use processing aftermath (ethanol yield, DDGS quality, starch yield and also quality, etc.), and difficulties in save the damaged grain without more deterioration.

Related reading

Bern, Carl and also Thomas Brumm. 2009. Grain Test weight Deception. Iowa State expansion Publication PMR-1005. Https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1035&context=abe_eng_pubs. .

Bradley, Carl. 2009. Diplodia Ear Rot Causing troubles in Corn throughout the State. The Bulletin, Univ of Illinois Extension. Http://ipm.illinois.edu/bulletin/article.php?id=1233. .

Hall, Glenn and Lowell Hill. 1974. Test weight Adjustment based on Moisture Content and Mechanical damage of Corn Kernels. Trans. ASAE 17:578-579.

Hellevang, Kenneth. 1995. Serial Moisture contents Effects and also Management. North Dakota State extension Publication AE-905. Http://www.ag.ndsu.edu/extension-aben/documents/ae905.pdf. .

Hellevang, Kenneth. 2012. Grain productivity Not related to Test Weight. Expansion & Ag research News, phibìc Dakota State Univ. Https://www.ag.ndsu.edu/news/newsreleases/2012/aug-20-2012/grain-yield-not-related-to-test-weight .

Hellevang, Kenneth. 2019. Plenty of Factors influence Corn check Weight. North Dakota State Univ. Extension. Https://www.ag.ndsu.edu/news/newsreleases/2019/nov-25-2019/many-factors-influence-corn-test-weight

Hicks, D.R. And H.A. Cloud. 1991. Calculating Grain weight Shrinkage in Corn as result of Mechanical Drying. gimpppa.org expansion Publication NCH-61 http://www.ces.gimpppa.org.edu/extmedia/nch/nch-61.html .

Hill, Lowell D. 1990. Serial Grades and Standards: Historical problems Shaping the Future. Univ. The Illinois Press, Champaign, IL.

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Hurburgh, Charles and Roger Elmore. 2008. Corn Quality issues in 2008 - Moisture and Test Weight. Integrated Crop monitoring News, Iowa State Univ. Extension. Https://crops.extension.iastate.edu/cropnews/2008/10/corn-quality-issues-2008-moisture-and-test-weight. .

Hurburgh, Charles and Roger Elmore. 2008. Corn Quality issues in 2008 – warehouse Management. Incorporated Crop management News, Iowa State Univ. Extension. Https://crops.extension.iastate.edu/cropnews/2008/10/corn-quality-issues-2008-�-storage-management. .

Laborie, Erin. 2019. Feeding irradiate Test weight Corn in Growing and Finishing Diets. Univ. The Nebraska Extension. Https://beef.unl.edu/beefwatch/feeding-light-test-weight-corn-growing-and-finishing-diets

Lingenfelser, woman (sr. Author). 2011. Kansas chop Performance Tests through Corn Hybrids (SRP1055). Kansas State University agricultural Experiment Station and also Cooperative extension Service, Kansas State Univ.

Nafziger, Emerson. 2003. Test Weight and Yield: A Connection? The Bulletin, Univ of Illinois Extension. Http://ipm.illinois.edu/bulletin/pastpest/articles/200323h.html. .

Rankin, Mike. 2009. Understanding Corn test Weight. Univ Wisconsin Extension. Https://fyi.uwex.edu/grain/files/2009/12/CornTW09.pdf.

Rusche, Warren. 2020. Feeding worth of Light-Test load Corn. IGrow, southern Dakota State Univ Extension. Https://extension.sdstate.edu/feeding-value-light-test-weight-corn

Simpson, Greg. 2000. An overview of study on Feeding low Test weight Corn to Pigs. Ontario to adjust of Ag, Food, and also Rural Affairs. Http://www.omafra.gov.on.ca/english/livestock/swine/facts/info_n_summary.htm

USDA-AMS (FGIS). Sep 1996. Subpart D that U.S. Criter for Corn. U.S. Standards. U.S. Room of agriculture - farming Marketing service (Federal Grain inspection Service). Https://www.ams.usda.gov/sites/default/files/media/CornStandards.pdf. .

USDA-AMS (FGIS). Oct 2020. Grain investigate Handbook, book II: grain Grading Procedures. United says Department of agriculture - farming Marketing service (Federal Grain investigate Service). Https://www.ams.usda.gov/sites/default/files/media/Book2.pdf

USDA-AMS (FGIS). . Test weight per Bushel. in Corn Grading Tutorial. United says Department of agriculture - farming Marketing service (Federal Grain inspection Service). Https://apps.ams.usda.gov/elearning/Grading/Grading_Corn/presentation_html5.html. .

U.S. Grains Council. 2020. Test Weight. in Corn violin Cargo top quality Report 2019/2020. U.S. Seed Council. Https://grains.org/corn_report/corn-harvest-quality-report-2019-2020/4/

Woloshuk, Charles and Kiersten Wise. 2009. Diplodia Ear Rot. gimpppa.org extension Publication #BP-75-W. Https://www.extension.gimpppa.org.edu/extmedia/BP/BP-75-W.pdf. .

Yang, P., R. J. Shunk, A. E. Haken, Y. X. Niu, S. H. Zou, P. Buriak, S. R. Eckhoff, M. E. Tumbleson. 2000. Yield, Protein Content, and Viscosity of strength from Wet-Milled Corn Hybrids as influenced by Environmentally Induced changes in test Weight. Grain Chemistry 77 (1):44-47. Https://onlinelibrary.wiley.com/doi/epdf/10.1094/CCHEM.2000.77.1.44 .