C.O.R.N. Newsletter : 2019 - 32

  1. Yield monitor calibration for fall harvest


    Harvest has not yet started here in Ohio, but it is good to remember to make sure your yield monitor is setup and calibrated properly. Geo-referenced yield data (i.e. yield maps) are being used to provide precision agriculture insights and recommendations at the field level. Yield maps not only help growers understand end-of-year performance within fields, but also can be used to characterize in-field variation. Information about this variation is often used by service providers to deliver prescriptions, recommendations, or other information back to the farmer. Because yield maps continue to be an important data layer to learn from and help drive changes or decisions at a field level, proper management of the yield monitor is critical to generate accurate and reliable yield data. Grain moisture and test weight, along with grain flow through the combine, will vary within passes and across fields. Therefore, the flow and moisture sensors on combines must be calibrated to these expected conditions in order to log accurate data.

    Why calibrate your yield monitor?

    • It helps collect accurate yield estimates so yield variability across the field is accurately represented by the yield map; especially this growing season considering the expected field variability.
    • It can be used to generate accurate prescriptions (Rx’s) and profit maps based on your yield maps. The generation of variable-rate fertility and seeding maps are frequently based on yield maps with few services creating profit maps to evaluate areas of profit and loss.
    • Yield maps have become a baseline data layer to assess management risks and the allocation of inputs. Precision agriculture practices have shown to provide feedback to improve profitability and helping confirm the best practices and input selections for a farm operation.

    Yield monitor best practices to use pre-harvest and during harvest

    • Be sure to update firmware and/or software for the yield monitoring systems. If necessary, contact your equipment or technology service provider about available firmware updates and where they can be downloaded.
    • Most yield monitors use a mass flow sensor at the top of the clean grain elevator. Due to the grain impact, the plate will wear to the point of developing a hole if it isn’t replaced soon enough. The wear that occurs changes the reading from the mass flow sensor. Be sure to replace the plate if wear is evident. Don’t neglect to recalibrate after replacing yield monitor components. This recalibration is necessary to ensure accuracy of the yield monitor. A more simple explanation is that a worn impact plate can result in an incorrect yield reading on your display. It is important to not overlook the yield mapping system as a worn component will throw off yield readings.
    • Update and/or configure DGPS. Software related to auto-steer, yield monitors and other GPS-based systems require separate attention. Licenses must be renewed. Calibrations and parameters must be updated or confirmed — especially if the display in the combine cab was used for planting or spraying earlier in the year. It’s necessary to meticulously switch every setting and value, from machine dimensions to type of crop and operation, so they are relevant to harvest operations.
    • Check auto-steer operations and that previously used AB/guidance lines are available within the display. Remember, you may have to adjust sensitivity settings.
    • It is also important to calibrate yield monitors for every crop, each season to ensure that all data being collected is as accurate as possible. The yield monitor needs to “be taught” how to convert the readings from the mass flow sensor into yield; therefore, it is necessary to show the yield monitor the range of yield conditions it will encounter throughout the season.
    • It is wise to periodically check the calibration throughout the season to be sure the data being collected is still accurate.
    • Grain moisture and density can vary between crop fields and, at times, vary significantly within a field. Accounting for changes in grain moisture and density improves the accuracy of yield estimates.
    • Remember to recalibrate if harvest conditions change. For example, if: yield monitor components are replaced or adjusted; grain moistures increase or decrease by over 6% to 8%; or after a rain shower but still dry enough to harvest.
    • The use of grain carts to calibrate yield monitors can be acceptable as long as it weighs accurately compared to certified scales. One should make sure the weigh wagon is on level ground (less than 2% slope) and stationary for a few seconds before documenting the weight.
    • Bring along your field notes so you can review them during harvest as crop conditions vary or issues are observed.
    • While harvest is a busy time, taking notes and images during harvest (especially if conducting on-farm research) can be valuable data when finally sitting down for post-harvest analysis and summary. We all forget, so notes and images can help document important information.

    For more information on calibrating yield monitors, check out the Ohio State Precision Ag website at https://digitalag.osu.edu/precision-ag plus read the Extension Publication “Tips for Calibrating Grain Yield Monitors — Maximizing Value of Your Yield Data” at https://ohioline.osu.edu/factsheet/anr-8.

    This article was re-printed from the August 28, 2019 edition of the Ohio Country Journal.

  2. Corn Silage, Too Wet or Too Dry?

    Cows Eating Silage
    Author(s): Bill Weiss, Mark Sulc

    Too Wet?

    For corn silage ideal moisture concentrations are between about 62 and 70%. They can be harvested a little wetter (maybe up to 72%) if it goes into a bunker. The wetter it gets the more seepage you get (loss of nutrients and potential environmental issues if seepage gets into a water source, example; Fish kill). Wet corn silage also produces an acetic acid-based fermentation which means a loss of energy (1 mole of glucose is fermented to lactic acid and acetic and 1 mole of carbon dioxide is lost, which is energy). Clostridia is not a major risk for corn silage because pH drops quickly but it can be a major concern for wet grass or alfalfa silage.

    Too Dry?

    Fires are caused when silage is chopped too dry. The silage doesn’t pack well, trapping oxygen which allows aerobic metabolism which produces a lot of heat. Wet hay is also a major risk factor for fire for the same reason, the wet hay allows aerobic metabolism (molds and yeast) which produce heat.  For more details please refer to the Penn State Factsheet, https://extension.psu.edu/silo-fires.

  3. Pricing Standing Forage Crops in the Field

    Hay Bale
    Author(s): Mark Sulc

    How to value a standing hay or haylage crop for sale directly from the field prior to harvest can be challenging.  Assigning an appropriate value includes the buyer and seller first agreeing on the market value for the hay and then adjusting for harvest costs and other factors that contribute to the price of hay sold in the open market, some of which are challenging to quantify.

    Two new factsheets and accompanying Excel worksheets tools are available to help you arrive at a fair price. These resources consider just a single crop of forage that is ready to harvest as hay or haylage.

    The grower’s base price equals the price they could receive for the crop from the hay market less harvesting/storage/marketing costs.  Hopefully, this covers production costs and generates a profit.  During price negotiations, it must be recognized that harvest risk is being shifted from the grower to the buyer, which should be applied as a further discount against the price paid by the buyer.

    Determining the market price of the harvested forage type that is growing in the field is perhaps the hardest part of the process. The adjustments to that price are a little more straightforward.

    For full details, click on the following links to learn how to calculate the value of forages in the field, considering the seller and buyer perspectives:

    1. Pricing perennial cool-season hay and annual warm-season grasses standing in the field – go.osu.edu/standinghayprice
    2. Worksheet tool to calculate the maximum price the buyer should pay for standing perennial cool-season hay and annual warm-season grasses in the field– go.osu.edu/standinghayprice-tool
    3. Pricing oat or spring triticale haylage standing in the field - https://go.osu.edu/standingoatforageprice
    4. Worksheet tool to calculate price of oat or spring triticale haylage standing in the field - https://go.osu.edu/standingoatforageprice-tool

    These are also available at https://forages.osu.edu, click on “Forage Management”, then “Forage Economics”.

  4. Drydown In Corn – What To Expect?

    Corn Stalk
    Author(s): Peter Thomison

    Many corn growers may encounter slower than normal drydown this fall due to late crop development associated with June planting dates. Much of Ohio’s late-planted corn may not achieve black layer until mid-October or later when drying conditions are less favorable for drydown.  Once corn achieves physiological maturity (when kernels have obtained maximum dry weight and black layer has formed), it will normally dry approximately 3/4 to 1% per day during favorable drying weather (sunny and breezy) during the early warmer part of the harvest season from mid‑September through late September. By early to mid‑October, dry-down rates will usually drop to ½ to 3/4% per day. By late October to early November, field dry‑down rates will usually drop to 1/4 to 1/2% per day and by mid-November, probably zero to 1/4% per day. By late November, drying rates will be negligible.

    Estimating dry‑down rates can also be considered in terms of Growing Degree Days (GDDs). Generally, it takes about 30 GDDs to lower grain moisture each point from 30% down to 25%. Drying from 25 to 20 percent requires about 45 GDDs per point of moisture. In October, we typically accumulate about 5 to 10 GDDs per day. However, note that the above estimates are based on generalizations, and it is likely that some hybrids may vary from this pattern of drydown. Some seed companies indicate considerably lower GDDs for grain moisture loss, i.e. 15 to 20 GDDs to lower grain moisture each point from 30% down to 25% and 20 to 30 GDDs per point from 25% to 20%.

    Past Ohio research evaluating corn drydown provides insight on effects of weather conditions on grain drying. During a warm, dry fall, grain moisture loss per day ranged from 0.76 to 0.92%. During a cool, wet fall, grain moisture loss per day ranged from 0.32 to 0.35%. Grain moisture losses based on GDDs ranged from 24 to 29 GDDs per percentage point of moisture (i.e., a loss of one percentage point of grain moisture per 24 to 29 GDDs) under warm dry fall conditions, whereas under cool wet fall conditions, moisture loss ranged from 20 to 22 GDDs. The number of GDDs associated with grain moisture loss was lower under cool, wet conditions than under warm, dry conditions.

    Weather related crop stress may affect drydown this year. Dr. Bob Nielsen at Purdue University notes, “When areas of fields die prematurely due to stresses like drought, spatial variability for grain moisture at harvest can be dramatic and often creates challenges with the management of the grain dryer operation. This is especially true early in the harvest season when grain moistures of healthier areas of the field are in the low 20's. The spatial variability for grain moisture decreases later in the harvest season as grain moistures throughout the field settle to an equilibrium level (15% or less).”

    Agronomists generally recommend that harvesting corn for dry grain storage should begin at about 24 to 25% grain moisture. Allowing corn to field dry below 20% risks yield losses from stalk lodging, ear drop, ear rots, insect feeding damage and wildlife damage.

    For more on grain drydown, check out the following article by Dr. Nielsen.

    Nielsen, R.L. 2018. Field Drydown of Mature Corn Grain. Corny News Network, Purdue Univ.
    URL: http://www.kingcorn.org/news/timeless/GrainDrying.html [URL accessed Sept. 23, 2019].

  5. Will Late Planted Corn Reach Black Layer Before a Killing Frost?

    Ohio saw record late corn planting in 2019.  According to the Agricultural Statistics Service, only 33% of Ohio's corn was planted by June 2.  The question being asked now is will the June planted corn reach physiological maturity (black layer) before a killing frost?  Corn is killed when temperatures are near 32°F for a few hours and when temperatures are near 28°F for a few minutes.

    A useful tool is available from the Midwestern Regional Climate Center (the U2U tool, available at:  https://mrcc.illinois.edu/U2U/gdd/) that uses current and historical weather data to predict when corn will reach black layer.  The user selects the geographic location that they are interested in, actual planting date and the adjusted relative maturity of the planted hybrid. 

    Previous studies have indicated that the GDD requirement of late planted corn to reach black layer from planting is less than the requirement of corn planted on a “normal” date.  Keeping this in mind, Dr. Bob Nielsen from Purdue University has developed an adjustment to the GDD requirements for late planted corn.  This calculator can be found at:  https://www.agry.purdue.edu/ext/corn/news/timeless/hybridmaturitydelayedplant.html  Using this calculator, enter the adjusted GDD value in the U2U tool in the “Black Layer GDDs” line.

    We have used the U2U tool to predict whether our corn research will accumulate enough GDDs before a killing frost.  Table 1 shows the results of using these tools for the 2019 Ohio Corn Performance Test sites (OCPT) as well as a late planted demo plot that was planted at Hoytville.  These results are based on a 109-day (2618 GDD) hybrid.  The table indicates the planting date, adjusted GDD requirement for the 109 day hybrid, whether physiological maturity (black layer) will be achieved before frost, the predicted black layer date and the average 32° and 28° frost dates.  Because of the adjusted GDD requirements with later planting dates, the predicted GDD accumulations will exceed or just meet the required GDDs before the average frost date for all 10 OCPT sites, including the 5 sites that were planted in June.  We hope that these predictions come true!  Note that the demo plots at Hoytville that were planted on June 27 will not reach black layer before a killing frost based on the U2U tool.

    Table 1.  Planting date, Adjusted Hybrid GDD Requirement, Reach BL Before Frost, Predicted Black Layer (BL) Date, and Average Frost Dates for 2019 Ohio Corn Performance Test sites.



    OCPT Test Site


    Plant Date


    Adjusted GDD1


    Reach BL Before Frost 2



    BL Date2


    Avg Frost Date (32°)


    Avg Frost Date (28°)















    Washington CH




























    Van Wert







    S. Charleston














    U. Sandusky







    Hoytville Demo







    1Based on a 109 day (2618 GDD) relative maturity hybrid.                                    

    2Based on the U2U GDD decision support tool.


    Nielsen, R.L.  2019.  Hybrid Maturity Decisions for Delayed Planting. Available at:  https://www.agry.purdue.edu/ext/corn/news/timeless/hybridmaturitydelayedplant.html

    Corn Growing Degree Day (GDD) decision support tool.  Available at:  https://mrcc.illinois.edu/U2U/gdd/

  6. The 57th Farm Science Review

    Combining Soybeans

    According to Nick Zachrich, the 57th Annual Farm Science Review saw attendance numbers with Tuesday 40,200, Wednesday 50,790 and Thursday 23,600 with a total attendance of 114,590.  The weather for the event was sunny, dry with above normal temperatures. 

    A summary of the field crop demonstrations at the Farm Science Review are summarized by Nate Dourdias, from a crop’s perspective, we had below average yields due to drought conditions that persisted in July and August. Soybean yields from 42-54 in 2.8 maturity group beans planted 4/18. Corn yields from a 95-day hybrid planted May 8 were 135-151 bu/ac. Corn moisture was 14-18%. NOTE, these maturities are not normally the recommended groups for the region. There are 500 acres dedicated to field demonstrations including demos and setup for all types of equipment.

    The eFields team made up of Ohio State University Extension Specialist and Educators passed out free water and eField cozies during the field demonstrations with water totals of Tuesday 1,500, Wednesday 2,200 and Thursday 1,000 with a total of 4,700.  

Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.


Allen Geyer (Research Associate, Corn Production)
Anne Dorrance (State Specialist, Soybean Diseases)
Chris Zoller (Educator, Agriculture and Natural Resources)
Clint Schroeder (Educator, Agriculture and Natural Resources)
Dean Kreager (Educator, Agriculture and Natural Resources)
Dennis Riethman (Educator, Agriculture and Natural Resources)
Elizabeth Hawkins (Field Specialist, Agronomic Systems)
Eric Richer, CCA (Educator, Agriculture and Natural Resources)
Garth Ruff (Educator, Agriculture and Natural Resources)
Glen Arnold, CCA (Field Specialist, Manure Nutrient Management )
Greg LaBarge, CPAg/CCA (Field Specialist, Agronomic Systems)
Harold Watters, CPAg/CCA (Field Specialist, Agronomic Systems)
Jason Hartschuh, CCA (Educator, Agriculture and Natural Resources)
Jeff Stachler (Educator, Agriculture and Natural Resources)
John Fulton (State Specialist, Precision Agriculture)
Lee Beers, CCA (Educator, Agriculture and Natural Resources)
Mark Badertscher (Educator, Agriculture and Natural Resources)
Mark Sulc (State Specialist, Forage Production)
Mike Gastier, CCA (Educator, Agriculture and Natural Resources)
Peter Thomison (State Specialist, Corn Production)
Pierce Paul (State Specialist, Corn and Wheat Diseases)
Rich Minyo (Research Specialist)
Sam Custer (Educator, Agriculture and Natural Resources)
Sarah Noggle (Educator, Agriculture and Natural Resources)
Stephanie Karhoff (Educator, Agriculture and Natural Resources)
Tony Nye (Educator, Agriculture and Natural Resources)


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