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A look back, a look ahead

While controlling costs in corn production is always a concern, there’s a renewed focus for 2015. With low market prices, profit margins are thin at best, and negative in some cases. If you are looking for places to reduce your cost of production, here are some thoughts based on conversations I’ve had with growers regarding various inputs.

A look back, a look ahead

While controlling costs in corn production is always a concern, there’s a renewed focus for 2015. With low market prices, profit margins are thin at best, and negative in some cases. If you are looking for places to reduce your cost of production, here are some thoughts based on conversations I’ve had with growers regarding various inputs.

Looking back at 2014, my first thought is something we saw in the spring. Tillage should be held at a minimum to help keep costs down. Be careful with secondary tillage. Some farmers worked ground too soon before planting in some areas of fields. That tillage was done with soil at less- than-ideal conditions, resulting in compaction. Also, some corn was planted in less-than-ideal soil conditions. Soils were unusually cool and roots didn’t grow normally.

The growing season overall in Iowa in 2014 was below normal in growing degree day accumulation each month. Hot spells let the crop catch up some on GDDs. And cool spells at critical times allowed good pollination and good grain fill.

Seed cost considerations

Some farmers are wondering if they really need to plant a hybrid that has a corn rootworm trait. They figure they can save perhaps $100 a bag by planting nontraited corn. My advice is not to cut out all traits, but the Bt corn borer trait is probably a pretty safe one to eliminate. If you are planting corn following soybeans in rotation, the rootworm trait is safe to eliminate.

Overall, don’t plant any traits you don’t need. For example, maybe you do or don’t need herbicide-tolerant traits. You can save substantially on seed cost by dropping the rootworm trait for corn following soybeans in a crop rotation and perhaps it may also make sense in your situation to drop the herbicide-resistant trait.

If you had northern corn leaf blight in 2014, consider putting that field into something other than corn in 2015. If you are going back to corn in that field, plant a hybrid with a good resistance rating for northern corn leaf blight. Likewise, if you had sudden death syndrome in soybeans, consider putting that field into something other than soybeans in 2015. If going back to soybeans in that field any time in the next several years, plant a bean variety with a good SDS rating.

Any other places to cut?

Run the N-rate calculator, an online tool, to see if you can cut your nitrogen application rate some from what you used when corn prices were high. With lower corn prices, the key is to lower the N rate just enough to keep the return on investment in N at its optimum, while not going so low as to limit economic return. At the same time, as the cost of applied N changes, the payback in increased yield changes. You want to apply N at the rate where the value of extra yield produced by the last pound of N applied equals the cost of that last pound of N.

Finding that sweet spot is complicated using pencil and paper, but quite simple using the N-Rate Calculator. Researchers have hundreds of site years of research data. Using this data, they have constructed the calculator, allowing you to input the price of N and the price of a bushel of corn. It is simple to learn to use and is user-friendly. See

While lower crop prices don’t pay for as much nitrogen, the same goes for pesticides. Fungicides should be used only when actual disease is present at the treatment threshold. Or when environmental conditions favor disease development — for instance, lots of cloudy, overcast days with high humidity and when dew is staying on the leaves for extended periods of time.

Insecticides should be used for treatment of insects that have actually reached the economic threshold. The threshold will be higher with cheaper corn prices because it takes a bigger yield loss to pay for the product and application.

Use soil test results for P and K application decisions. If soil is at optimum level for P and K, apply maintenance rates of fertilizer; apply just the amount of P and K you hauled off in crop yield in 2014. In fact, this is something farmers should be doing all the time. You can find removal rates in ISU publication PM 1688, “General Guide for Crop Nutrient Recommendations in Iowa.”

Can you skip applying P and K if your soils test optimum for P and K? You could skip one or two years if the soil test results are in the optimum category. You should skip all the time when soils test high or very high for P and K.

What about weed control?

Be careful trying to shave weed control costs. Use a preemergence herbicide that provides residual control and use a post-emergence herbicide. Residual control can be provided by both a preemergence and some postemergence herbicides.

To help avoid problems with herbicide-resistant weeds developing, use a herbicide program that has more than one site of action in the products you apply. In other words, the preemergence herbicide has a different site of action than the postemergence herbicide. It is good to use more than one site of action with each application. Each site of action has a herbicide group number. Most herbicide labels show the group number or numbers (in the case of premixes) near the top of the label.

Consider downloading ISU publication WF 94, the “2015 Herbicide Guide for Iowa Corn and Soybean Production” at The free download is helpful in planning your 2015 herbicide program. You can also pick up a free copy at your ISU county Extension office.

Another good resource is, where you can enter the name of any pesticide, herbicide, insecticide or fungicide, and it will give you the label. This tool lets you enter a herbicide name and then read the label to see which weeds it controls.

Choose your 2015 herbicide program based on weeds you had in 2014. In fields where weeds weren’t controlled by your herbicide, don’t apply the same herbicide in 2015. Find one in a different herbicide group, one with a different site of action.

Going back to soybeans?

Looking at the corn-bean price ratio the market is offering, some farmers say they’ll plant more soybeans and less continuous corn in 2015. There are a couple of considerations when switching continuous cornfields back to beans.

If a field has been in corn five years or more, there’s a very good chance you’ll get higher-than-normal bean yields. If the field has been in continuous corn that long, there’s a very good chance it will have low numbers of soybean cyst nematode. This should be a favorable yield environment, so look for a high-yielding soybean variety to plant in such fields.

Also, be sure to check out the planting interval for 2014’s herbicide application on that field. If the 2014 corn herbicide you applied went on late in the spring with a full rate applied, there may be some carryover issues for soybeans if you plant beans in that same field in 2015.

Johnson is the ISU Extension field agronomist for central Iowa. He can be contacted at

Pesticide ed program gets new name

The Pest Management and the Environment program at Iowa State University Extension recently changed its name to the Pesticide Safety Education Program. The new name better describes the program and how it provides information on safe and effective use of pesticides.

PSEP is responsible for providing pesticide safety education to various audiences in Iowa, including certified commercial, public and private applicators, and pesticide safety awareness for the general public. In addition to applicator certification, PSEP is involved in other areas of education including integrated pest management, worker protection, environmental quality and agricultural health. To keep current on pesticide issues, PSEP staff are active on national boards, including the American Association of Pesticide Safety Educators, Certification and Training Assessment Group, and Pesticide Stewardship Alliance.

For information about PSEP programs, go to To access PSEP publications, visit

During 2013, PSEP and other ISU Extension staff provided Continuing Instructional Course training to nearly 26,000 certified applicators who control weeds, insects, disease-causing organisms, rodents and other pests in agricultural cropping systems, forests, structures, turf, ornamentals, rights-of-way, aquatic areas and other sites.

This article published in the January, 2015 edition of WALLACES FARMER.

All rights reserved. Copyright Farm Progress Cos. 2015.

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