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Ohio State University Extension


C.O.R.N. Newsletter 2011-08

Dates Covered: 
April 11, 2011 - April 18, 2011
Steve Prochaska
Proven Production Practices for Increasing Corn Yields and Profits

Proven Production Practices for Increasing Corn Yields and Profits

The record high corn yields achieved by many Ohio farmers in recent years have generated considerable interest in what can be done to sustain and push yields even higher. Many Ohio growers are achieving 200 bu/A corn. According to some agronomists and crop specialists, we have entered a new era in corn production characterized by higher annual rates of yield improvement. These higher rates are attributed to several factors, including genetic technologies that allow for greater expression of corn genetic yield potential by withstanding various crop stresses.

In the quest for high yields, considerable attention has been given to increasing various inputs, including seeding rates and fertilizers, narrowing row spacing, and making preventative applications of foliar fungicides, growth regulators and biological stimulants. However, the additional costs of some of these practices and inputs may prohibit their use except perhaps for those growers interested in participating in corn yield contests on high yielding sites.

A more practical and economic approach to achieving high yields is to follow

proven cultural practices that enhance corn performance. Not only are these practices the foundation for successful corn production but they will also help exploit the yield potential offered by new technologies.

Eleven Proven Practices for Increasing Corn Yields and Profits

  1. Know the yield potential of your fields, their yield history, and the soil type and its productivity.
  2. Choose high yielding, adapted hybrids. Pick hybrids that have produced consistently high yields across a number of locations or years. Select hybrids with high ratings for foliar and stalk rot diseases when planting no-till or with reduced tillage, especially after corn. Select high yielding Bt rootworm resistant hybrids where is potential for the western corn rootworm damage.
  3. Follow pest management practices that will provide effective, timely pest control; especially weed control.
  4. Aim to complete planting by May 10. If soil conditions are dry, begin planting before the optimum date but avoid early planting or poorly drained soils. If planting late (after May 25 in central Ohio) plant corn borer resistant Bt hybrids.
  5. Follow practices that will enhance stand establishment. Adjust seeding depth according to soil conditions and monitor planting depth periodically during the planting operation and adjust for varying soil conditions. Make sure the planter is in good working order. Inspect and adjust the planter to improve stand establishment. Operate planters at speeds that will optimize seed placement. Uneven emergence affects crop performance because late emerging plants cannot compete with larger, early emerging plants.
  6. Adjust seeding rates on a field by field basis. On productive soils, which average 175 bu/A or more, final stands of 32,000 plants/acre or more may be required to maximize yields.
  7. Supply the most economical rate of nitrogen. Use an application method that will minimize the potential loss of N (incorporation/injection, consider stabilizers under high risk applications, etc.).
  8. Utilize soil testing to adjust pH and guide P and K fertilization. Avoid unnecessary P and K application.  High soil tests do not require additional inputs.
  9. Perform tillage operations only when necessary and under proper soil conditions. Deep tillage should only be performed when a compacted zone is detected and soil conditions are dry (usually late summer).
  10. Take advantage of crop rotation - corn grown after soybeans will typically yield 10-15% more than corn grown after corn.
  11. Monitor fields and troubleshoot yield limiting factors throughout the season

These are by no means the only management practices with which growers need to be concerned but they are keys to achieving high corn yields.

Nitrogen Inhibitors, What is What and Should You Consider Their Use?

Now that we finally have a hint of spring, producers start thinking about planting corn and planning on nitrogen fertilization applications.  In case you have not noticed, fertilizer prices are a little higher than they were this time last year.  This typically leads to questions like – “should I consider the use of an inhibitor?”  The goal of this article is to cover (very briefly) the inhibitors that are out there, what they do, and where their use should be considered.

Multiple universities conduct field research with inhibitors to determine effectiveness, but lab studies conducted to determine proof of mode of action are more critical to our understanding of their usefulness.  Several inhibitors have sound lab evidence that they do what they are promoted to do (and some do not), but we may struggle to find usefulness from field studies.  Thus we, as university researchers, attempt to identify nitrogen sources, application methods, and application timings that are more likely to benefit from the use of these inhibitors.

Urease Inhibitors

First we will discuss urease inhibitors.  Urea based nitrogen fertilizers are an organic commercial form that requires a biological enzyme to promote degradation to ammonia.  Ammonia exists as a gas at normal temperature and pressure, thus it may be lost by volatilization if not exposed to water.  Ammonia loss potential by volatilization for incorporated urea products is negligible because soil holds enough water to capture ammonia as ammonium that can be held on the soil’s cation exchange complex.  Surface applications of urea are at risk of loss because there is no opportunity to capture the ammonia as it is produced.

Urease inhibitors can have different modes of action, and the first question we should ask is do they work?  The active ingredient in the inhibitor can act as a substrate for the urease enzyme, thereby protecting free urea by allowing it to stay in solution longer, or the inhibitor can inactivate the enzyme.  Agrotain® is the most common commercially available urease inhibitor.  The active ingredient in Agrotain® is N-(n-butyl) thiophosphoric triamide.  The mode of action is not clearly defined, but it is thought to act as a substrate for the urease enzyme.  Regardless of the mode of action, laboratory evidence has shown that it does allow urea to be retained in the soil longer.

Other urease inhibitors are marketed, some may have some activity, but it is your job as a producer/consultant to determine whether or not the proposed mode of action makes sense.  We would also encourage you to inquire about lab data indicating that the material being marketed does what it is supposed to do. 

Even if a urease inhibitor has been demonstrated in a laboratory to have some inhibition properties on the enzyme urease, the agronomic question still remains as to its usefulness in a field setting.  It really depends upon how nitrogen is to be applied (and the form) and the rate of nitrogen being applied.  Higher rates of urea nitrogen (under most conditions) likely do not require urease inhibitors.  Surface application of dry urea in high residue situations is a good place for the use of urease inhibitors.  Dribble applications of liquid UAN may benefit from a urease inhibitor in high residue situations, but clean till fields are less likely to benefit.  Injected liquid UAN (whether it is knifed or coultered) does not require stabilizers based upon current research.

Nitrification Inhibitors

Nitrification inhibitors are the other inhibitors marketed, but they have a completely different mode of action.  Any nitrogen supplied as a commercial fertilizer is ultimately transformed to a nitrate form of nitrogen (or at least a significant fraction of that supplied).  In the presence of adequate oxygen, warm temperatures (> 50 F), and some moisture, ammonium-N is converted to nitrate-N through a biochemical process (known as nitrification) that requires two forms of soil bacteria.  The first bacterium Nitrosomonas converts ammonium-N to nitrite-N.  The second bacterium Nitrobacter converts nitrite-N to nitrate-N.  And as you know, nitrate-N is the form we are most concerned about being lost (whether by leaching or denitrification).

Nitrification inhibitors have one primary way of delaying the nitrification process, and that is eliminating the bacteria Nitrosomonas in the area where ammonium is to be present.  There are three common nitrification inhibitors that are commercially available:  2-chloro-6-(trichloromethyl)-pyridine (nitrapyrin), dicyandiamide (DCD), and ammonium thiosulfate (ATS).

Nitrapyrin is the active ingredient found in the DOW® product N-Serve® and Instinct®.  The biochemical activity of nitrapyrin and its ability to suppress growth of Nitrosomonas has been known since the 70s and it was initially registered in 1974.  It is quite effective even at relatively low rates.  Dicyandiamide (DCD) is the active ingredient in nitrification inhibitors such as Agrotain Plus®, SuperU® , and Guardian®.  Dicyandiamide is required at a significantly larger concentration to be effective.

Since each of the products discussed above is highly sensitive to concentration, it is imperative that if they are used they are applied at labeled rates.  Cutting rates is not in your best interest as an end user because a lower concentration may not allow the product to perform its job in the soil.

Applying anhydrous with nitrapyrin in the fall (which is not our recommendation for summer crops in Ohio) may realize a benefit of the nitrapyrin (as it is out in the field for a long time), but for most of us who apply anhydrous ammonia in the spring soon before planting and as a sidedress treatment, the utility of a nitrification inhibitor is difficult to justify since the risk of N loss is low.  No-till situations are more likely to show positive yield results than conventional till systems for spring applied anhydrous. 

Nitrification inhibitors are less likely to show an economic benefit when high N rates are used in the field.  Nitrogen losses at high N application rates are not likely to affect yield as much if lower N rates are applied (fewer bushels per acre are gained with each additional level of N at the high levels).


Application timing, N source, application method, soil texture, and tillage are all factors that should be evaluated to determine where urease and nitrification inhibitors should be used.  Before buying an inhibitor make sure scientific evidence backs up its claim.  .A producer and/or consultant should be wary of any product that does not have solid scientific data demonstrating that the inhibitor activity matches the advertised benefit.

On-Farm Field Trials – How to Lay Them Out

More and more inputs are being pushed onto producers to raise yields. Some products have a substantial amount of data behind them and for others it is hard to find data. But producers can evaluate these treatments on their own farms. Plan now to leave non-treated strips in the field. This does not mean, the better half of the field gets the treatment and the other half doesn’t, which has been shown to be very biased.   To ensure a fair representation, plan to have the treatments cross the field in replicated strips. The direction of the strips should be such that parts of both the treated and nontreated strips are in both the light and dark ground. In other words, if the dark and light ground or woods at the edge of the field runs east-to-west, the treated and nontreated strips should run north-to-south.  Alternate the treatment strips across the field:

For example, if you have 2 comparisons, A and B, arrange them as follows:  A B, B A, A B, or A B, A B, B A

If you have 3 comparisons, A B and C, arrange them as follows:  A B C, B C A, B A C, C B A

As you set these comparisons up in the field, arrange them in widths wider than the combine. For aerial applications, plan for 3 widths to account for drift.  Since the fields are wet in many areas of the state, now is a good time to get out and put some flags in where these different treatments will go. A little prep work now before planting will make it easy when planting has to happen – and again when it is time to harvest to know which treatments are which and then monitor them through the summer.

If you need any assistance in monitoring, we would be glad to help. We expect to be short handed this summer, but if we have sites nearby, it would be nice to see what Ohio producers are looking at and what the challenges are.  Many factors (such as variety or hybrid, soil type, soil drainage, SCN population, soil pH, soil fertility, rainfall, temperature, etc)  can influence the response of plants to different treatments.  Keeping notes on the above and other relevant factors will be important to understanding yield response to treatment.

Soybean Aphid in Ohio in 2011

Soybean Aphid in Ohio in 2011

Normally during this time we offer an up-date article as to our thoughts for soybean aphid in Ohio for the coming summer.  We reported our initial thoughts last fall in the C.O.R.N. Newsletter, 2010-38 that we do expect to see some aphids this coming summer.   If you remember, we saw extremely few aphids during 2010 except for the last few weeks of summer which is normal during an “off” year.  While not seeding a lot of eggs on buckthorn, some were indeed found which suggests an “aphid” year coming up.  Thus, we feel that Ohio will continue its two year cycle of very few if any aphids being found followed by low to moderate to even high populations somewhere in the state.  But as we stated last fall and throughout the winter meetings, it is impossible to predict which regions of Ohio, if any, will experience outbreak conditions.  There are many factors that will determine this, including environmental weather conditions (temperatures, rainfall, etc.) to the presence and effectiveness of biological control agents such as predators, parasitoid, and pathogens. 

At this time, growers should just be aware that scouting for aphids will probably be more important this summer.   There is nothing to suggest that any additional measures should be taken at this time.  Another article in this newsletter offers a management tool, SoyPod DSS, that can assist with scouting for the soybean aphid that makes use of the Speed Scouting protocol along with a WEB-BASED program usable on smartphones and tablets.


SoyPod DSS: A Web-Based, E-Scouting Tool for Soybean Aphid Management

We all know of some of the difficulties of scouting for soybean aphid and determining management recommendations.  Extension entomologists throughout the Midwest are always working on more “user-friendly” tools, such as the Speed Scouting protocol created by the University of Minnesota (see in 2004.

This Speed Scouting protocol has now gone paperless.  Dr. Brian McCornack (Dept. of Entomology, Kansas State University) and John Tinetti (SwerveSoft, Inc.) has developed SoyPod DSS (Decision Support System,, which can be used with any device that can access the web, particularly smartphones and tablets (iPad, galaxyTab, etc.).  The tool is FREE, and users simply provide information for commercial soybean fields that will be sampled weekly during periods of soybean activity.  The weekly scouting allows SoyPod DSS to track resampling intervals (RSI), which is critical for decisions on soybean aphid management.  Remember, the economic threshold is a rising population of 250 aphids per plant—SoyPod DSS can monitor the progression of aphid reproduction based on the information you provide.  After entering the data for each sampling period, SoyPod DSS will provide a management recommendation for each field sampled.  Current features of the program include adding field information and data, Speed Scouting reports, and a viewable table of previous reports for your fields.  Future features will include scheduling a treatment, automated temperature downloads, field-specific economic injury levels and thresholds, and maps for integrating data throughout the Midwest.  More information on the new tool can be found at

Alfalfa Weevil Update

Alfalfa Weevil Update

At this time, the only stations reporting sufficient heat units to suggest sampling for alfalfa weevil continues to be those in southern Ohio, Piketon at 282 HU and Jackson at 318 HU.   South Charleston (OARDC Western Station) is only at 200 HU while the more northern locations are barely over 100 HU.  See last week’s newsletter for information on sampling for alfalfa weevil.

Corn Growth Classic Rewritten and Recommended for Reference

Dr. Peter Thomison, Ohio State University Extension Corn Specialist, recommends  this new publication as fine reference for people in production agriculture.

The Iowa State University Extension's corn production team has completed a new publication. “Corn Growth and Development” (PMR 1009) that  replaces “How a Corn Plant Develops,” the previous Iowa State publication that served as the standard reference on corn growth and development for more than 40 years.

Authors of the 2011 publication “Corn Growth and Development”,  that provides an in-depth look at corn, from the moment the seed is planted all the way to maturity,   were Lori Abendroth, ISU associate corn agronomist; Roger Elmore, ISU Extension corn specialist; Matthew Boyer, former ISU agronomy graduate student; and Stephanie Marlay, ISU agronomy specialist.

In the development  of the new publication, the team conducted multiyear research trials, read piles of research papers, and grew hundreds of plants. Research on biomass and nutrient accumulation was conducted  along with other trials to fine-tune recommendations and facts in the book.

The new publication weaves the latest scientific facts regarding corn growth and development in a way that is concise and easily applicable for people in production agriculture.

Key features of the new publication include the following:

  • more than 90 images, including whole-plant images from emergence to maturity
  • detailed descriptions of vegetative and reproductive development
  • new dry matter and nutrient (N, P and K) accumulations figures clarification of corn development staging methods
  • an expansive list of end notes with agronomic research references

“Corn Growth and Development” can be ordered from the ISU Extension Online Store ( for $14 per copy. Publication images will soon be available to purchase and download from the same location.

New Corn, Soybean, Wheat, and Alfalfa Field Guide

As a reminder, a new version of Bulletin 827 Corn, Soybean, Wheat, and Alfalfa Field Guide is available at OSU’s e-store ( for purchase at $13/copy. A 10% discount is available if more than 50 copies are ordered.  The new version has a spiral binding to be able to flip through the pages more easily. 

Many of the sections have new pictures and updates. In additions, new sections were added to address issues related to application technology and sampling and testing for mycotoxins. This book is a must have for the pickup truck and sprayer as you scout alfalfa, corn, soybeans and wheat for weeds, insect, diseases and fertility issues. This guide puts many essential pieces of information at your finger tips in the field where you need it most. This publication has been awarded the Certificate of Excellence from the American Society of Agronomy for outstanding agronomic educational material.

Livestock Industry: May 2 Workshop in Columbus Tackles Ammonia Emissions and Connection to Nitrogen Fertilizer

This year’s Ohio State University agricultural air quality workshop will focus on the challenges and opportunities facing livestock and poultry producers when it comes to ammonia emissions and their connection with nitrogen fertilizer. It will take place Monday, May 2, at the Nationwide and Ohio Farm Bureau 4-H Center in Columbus.

Aimed at farmers, allied animal agriculture industries, agency professionals and regulators, the workshop will provide a fundamental understanding of ammonia emissions, air regulations, and the best management practices and innovative technologies available for the abatement and recovery of these emissions — both to protect the environment and to create an alternative solution for fertilizer needs in farming.

Registration for the event, which will run from 8:30 a.m. to 4:30 p.m., costs $35 before April 25 and includes lunch. Registration after April 25 costs $45. To register, download a form at, fill out and mail with payment to the address indicated on the form. You can also contact Amanda Meddles, OSU Extension, at 614-292-6625.

Ammonia emissions have become a significant concern as they impact public health, air quality and ecosystem acidity. Most ammonia emissions into the atmosphere in the United States (81 percent or 2.4 million tons) are generated by animal production, and air quality regulations make producers vulnerable to lawsuits enforcing emission rules.

Despite these environmental and regulatory challenges, ammonia — which contains nitrogen — can also become a source of fertilizer to enhance the profitability and sustainability of animal-feeding operations. Workshop participants will learn about a variety of research-based strategies to reduce ammonia emissions and capture nitrogen for fertilizer use.

Topics include ammonia reporting requirements and procedures in Ohio, tools to estimate ammonia emissions, an overview of ammonia mitigation best management practices, impacts of various diets on animal excretion of ammonia, field tests of bio-filters at swine facilities, manure covers and management of manure land application to reduce air emissions, and use of wet scrubbers to recover ammonia emissions. Check out for a complete list of topics.

Presenters at the workshop include air quality, livestock housing systems, animal nutrition and composting experts from Iowa State University, the University of Illinois, the University of Missouri, Ohio State and the Ohio Environmental Protection Agency (EPA).

Certified livestock managers can earn three continuing education credits at the event.

Workshop sponsors include Ohio EPA, the Ohio Livestock Coalition, the Ohio Department of Natural Resources, and the U.S. Department of Agriculture’s Natural Resources Conservation Service.

The 4-H Center is located at 2201 Fred Taylor Dr. on Ohio State’s Columbus campus. Directions are available at:

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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.