Grain Test Weight Considerations for Corn

R.L. (Bob) Nielsen
Agronomy Dept., Purdue Univ.
West Lafayette, IN 47907-2054
Email address: rnielsen at purdue.edu
Twitter: @PurdueCornGuy

Among the top 10 most discussed (and cussed) topics at the Chat ‘n Chew Cafe during corn harvest season is the grain test weight being reported from cornfields in the neighborhood. Test weight is measured in the U.S. in terms of pounds of grain per volumetric “Winchester” bushel. In practice, test weight measurements are based on the weight of grain that fills a quart container (37.24 qts. to a bushel) that meets the specifications of the USDA-AMS (FGIS) for official inspection (Fig. 1). Certain electronic moisture meters, like the Dickey-John GAC, estimate test weight based on a smaller-volume cup. These test weight estimates are reasonably accurate but are not accepted for official grain trading purposes.

The official minimum allowable test weight in the U.S. for No. 1 yellow corn is 56 lbs/bu and for No. 2 yellow corn is 54 lbs/bu (USDA-AMS (FGIS), 1996). Corn grain in the U.S. is marketed on the basis of a 56-lb “bushel” regardless of test weight. Even though grain moisture is not part of the U.S. standards for corn, grain buyers pay on the basis of “dry” bushels (15 to 15.5% grain moisture content) or discount the market price to account for the drying expenses they expect to incur handling wetter corn grain.

Growers worry about low test weight because local grain buyers often discount their market bids for low test weight grain. In addition, growers are naturally disappointed when they deliver a 1000 bushel (volumetric bushels, that is) semi-load of grain that averages 52-lb test weight because they only get paid for 929 56-lb “market” bushels (52,000 lbs ÷ 56 lbs/bu) PLUS they receive a discounted price for the low test weight grain. On the other hand, high test weight grain makes growers feel good when they deliver a 1000 bushel semi-load of grain that averages 60 lb test weight because they will get paid for 1071 56-lb “market” bushels (60,000 lbs ÷ 56 lbs/bu). Continue reading

Do your Ears Hang Low? – Premature Ear Declination in Corn

Collapsed ear shank of droopy ear

Collapsed ear shank of droopy ear

Taken from Purdue Extension, Chat and Chew Cafe – September 11, 2020 – Issue 2020.24 – By Bob Nielson

Droopy ears are cute on certain breeds of dogs, but droopy ears on corn plants prior to physiological maturity are a signal that grain fill has slowed or halted. Ears of corn normally remain erect until some time after physiological maturity (black layer development) has occurred, after which the ear shanks eventually collapse and the ears decline or “droop” down. The normal declination of the ears AFTER maturity is desirable from the perspective of shedding rainfall prior to harvest and avoiding the re-wetting of the kernels. PREMATURE ear declination, however, results in premature black layer formation, lightweight grain, and ultimately lower grain yield per acre.

What Causes Premature Droopy Ears? The most common contributing factor is severe drought stress that extends late into the grain-filling period. I have seen droopy ears in quite a few fields around Indiana these past few weeks in areas afflicted with severe drought stress. Even though Indiana has not experienced a lot of excessively hot (≥ 95o F) days in 2020, drought conditions coupled with sunny days and unusually low humidity (i.e., low dew point temperatures) result in significant evapotranspiration demands on the crop during grain filling. In most of the affected fields, the severity of leaf rolling and premature leaf death (senescence) due to drought stress was also high. Continue reading

Tar Spot – What is it?

Figure 2. Tar spot symptoms on leaves both on the lower and the upper canopy. (Photo Credit: Darcy Telenko)

While I have been out in Paulding county scouting in the last week, I have not noticed any tar spot in our cornfields as of yet.  It could be there though as I am not walking in every field. I wanted producers to take note of what Tar Spot looks like and some monitoring from our neighbors in Indiana and information from a previous CORN New Article.  Continue reading

New Crop Staging Videos

A new suite of crop staging videos has been built by faculty at The Ohio State University that highlight corn, soybean, and alfalfa. The videos highlight some common staging methods for each crop and connect the staging guidelines to practice using live plants in the field. The videos can be found in the “Crop Growth Stages” playlist on the AgCrops YouTube Channel: https://www.youtube.com/channel/UCbqpb60QXN3UJIBa5is6kHw/playlists. These compliment some of the wheat staging videos previously posted on the AgCrops YouTube channel as well. As the crops progress through the reproductive stages, expect some more videos to be posted! Continue reading

Revisiting Corn Use for Ethanol

By: Todd Hubbs, Department of Agricultural and Consumer Economics, University of Illinois.  farmdoc daily (10):133

Stronger export numbers and lower acreage boosted corn prices since the end of June.  Concerns about demand weakness in ethanol production emerged recently.  A recovery in economic activity helped ethanol plants ramp up production as gasoline demand increased.  A resurgence in virus incidences threatens ethanol production over the short run and injects uncertainty into long-run prospects.

Gasoline demand recovered to almost 89 percent of pre-coronavirus lockdown levels in early July.  Despite this positive development, the recovery in demand flattened out over the last few weeks.  Gasoline stocks began to recede but still sit substantially above levels seen at this time of the year.  Attempts to reopen the economy hit a snag as the virus spread rapidly around the country after initial hopes saw a rapid opening in many areas.  At 8.648 million barrels per day, demand recovered substantially from the low point of 5.311 million barrels per day seen in early April.  The path back to normal gasoline demand levels appears stalled.  Ethanol production followed this recovery and will feel the implications of flattening gasoline use. Continue reading