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Ohio State University Extension


C.O.R.N. Newsletter 2007-03

Dates Covered: 
February 6, 2007 - February 20, 2007
Harold Watters

Key Steps for Managing the Risks of Continuous Corn

Authors: Peter Thomison

Given the potential for greater economic returns, many grain farmers are planning to increase their corn acreage in 2007. Although much of this additional corn will be produced in fields following soybean or wheat, some will be produced in fields following corn. Continuous corn is not recommended by most agronomists. In Ohio, corn grown following soybeans typically yields about 10% more than continuous corn. Benefits to growing corn in rotation with soybean include less disease and insect buildup, less crop residue, and less nitrogen fertilizer use. Growers who intend to plant second year corn should consider management practices that will minimize potential yield losses. The following are some key steps for managing risks of corn following corn.

1. Plant corn on the most fertile, well drained soils to reduce stress and maximize yield potential. Avoid droughty soils as well as poorly drained soil conditions. Studies across the Corn Belt have shown that the yield differential between continuous corn and corn grown in rotation with soybeans is greatest when yield potential is low. This yield advantage to growing corn following soybean is especially pronounced when drought occurs during the growing season. In a study conducted in Minnesota, the yield advantage to an annual rotation of corn and soybean compared with monoculture was frequently greater than 25% in low yielding environments.

2. Plant Bt rootworm resistant corn hybrids or apply soil insecticides in areas where western corn rootworm problems have occurred. Bt corn requires a 20% refuge planted to non-Bt corn to prevent resistance development. Corn rootworm problems on refuge acres may be managed with soil-applied insecticides, or high rate formulations of seed treatments.

3. Adjust nitrogen rates. Optimum nitrogen rates for corn after corn are generally higher than those for corn after soybean and the additional nitrogen required ranges from 30 to 50 lbs nitrogen/ A.

4. Select hybrids that have demonstrated high yield potential across diverse environments and stress conditions. Only hybrids with above average ratings for drought tolerance, stalk strength, and emergence under stress conditions (low temperatures and cold, wet soils) should be considered. Select corn hybrids with resistance to gray leaf spot, northern corn leaf blight, anthracnose and gibberella stalk rots, and diplodia ear rot. The severity of these disease problems is much greater in reduced tillage systems where residues are present. In the past, the use of foliar fungicides has not been considered economical for disease control in field corn regardless of the rotation followed. Strobilurin fungicides have received much attention recently but university data on their efficacy is limited.

5. Develop strategies for dealing with increased crop residues. Use stalk choppers and knife rolls on combine heads, spread trash uniformly during harvest, consider strip tillage, avoid no-till where practical, avoid no-till planting on top of old rows, use row cleaners and seed firmers, and plant hybrids with good disease resistance, emergence, and seedling vigor.

Studies in Ohio and Indiana have shown that increasing the amount of tillage from no-till to chisel to moldboard plow decreases the yield difference between continuous corn and corn rotated with soybean, especially on poor drained soils. No-till cropping systems are more likely to succeed on poorly drained soils if corn follows soybean rather than corn. The influence of crop rotation on corn response to tillage and soil type has been well documented in long-term OSU-OARDC studies. On poorly drained Hoytville silty clay soils in NW Ohio, where corn followed soybean, yield differences between no-till and tilled ground were greatly reduced. Crop rotation with soybeans had much less effect on corn response to tillage on well-drained Wooster silt loam soils in NE Ohio.

Fall Anhydrous Ammonia, Should You Be Concerned?

Authors: Robert Mullen, Edwin Lentz

Nitrogen continues to be a hot topic of conversation and with the uncertainty of spring prices and the possible availability issues (due to increased corn acres) some producers applied anhydrous ammonia last fall. Unfortunately, we have had a rather warm, wet late fall and early winter and the question being asked is – how much N have I potentially lost?

We are unable to quantify how much has been lost because of the dynamic nature of nitrogen and the variability of weather conditions across the state, but we can tell you that we are concerned that at least a fraction of the nitrogen has been lost. How much may have been lost depends when you applied it (did soil temperatures remain below 50? F after application) and whether a nitrification inhibitor was used. If applied after November 1 with a inhibitor, losses may be minimal. However, this inability to predict the potential loss is one of the reasons Ohio State University does not recommend fall applied nitrogen. Now the question is how do you identify if additional nitrogen will be needed this spring? Presidedress soil nitrate test (PSNT) is one tool that could be used to assess soil nitrogen supply. Soil samples should be collected in mid to late-May to a depth of one foot. Fields with nitrate levels greater than 25 ppm are unlikely to respond to additional nitrogen, but fields with less than 25 ppm may require additional nitrogen input. The rate of nitrogen applied should not be greater than 70 pounds per acre (if PSNT is less than 25 ppm). Tissue testing can also be used to evaluate the crop during the growing season. The only thing to be cognizant of is the potential influence of the growing environment. If it is a cool, dry, or exceptionally wet spring, tissue testing may reveal a deficiency that is not related to soil nutrient availability. The presence of the deficiency is due to adverse growing conditions.

An alternative tool that may be useful to evaluate fall N programs is the establishment of a nitrogen rich test strip. Typically 100 pounds of N per acre are applied in a small strip (applicator’s width) to compare with the rest of the field. This visual comparison may help answer nitrogen availability questions throughout the growing season.

Keep an eye on your corn and be ready to act if necessary.

Approval for Agrisure CB/LL/RW

Authors: Ron Hammond, Bruce Eisley

Syngenta has just announced that they received approval from the EPA for their new stacked transgenic corn, Agrisure CB/RW. This product combines the resistant genes for both the European corn borer and corn rootworm larvae. Because of the manner in which they developed this combination, it also has the LL gene for Liberty herbicide resistance; thus, it will be called Agrisure CB/LL/RW. A few hybrids containing these traits will be available for 2007. A four way trait containing these three along with glysophate resistance, Agrisure GT/CB/LL/RW, will be available in 2008. This stacked trait from Syngenta combining corn borer and rootworm resistance now joins YieldGard Plus and Herculex Xtra as transgenic corn hybrids able to manage both insect pests.

Regional Agronomy Offerings Upcoming

Authors: Harold Watters

See below but you may also check our website to keep aware of upcoming local events:

1) ----

Soil Compaction and Agricultural Technology Meeting
February 27 Time: 10:00 a.m. - 2:00 p.m.
County of Meeting Location: Paulding
Location: Paulding County Extension Building
Address: 503 Fairground Dr, Paulding 45879
Cost: No Cost
For more information: Jim Lopshire at or 419-399-8225

2) ----

2007 Tri-County Agronomy Day (Carroll, Harrison, Jefferson) February 27th.
To be held in Our Lady of Mercy Catholic Church Hall in Carrollton Ohio from 10 AM to 3PM. The registration is $8 and includes morning refreshments, a hot lunch and a new Weed Control Guide.
Topics featured include:
• Herbicide updates for 2007
• Diagnosing & correcting Corn Problems
• Roundup Ready Alfalfa
• Extending the grazing season with annuals
• Energy & input outlook for 2007
• Doing business with Harrison Ethanol
• Feedgrain prices: How high and how long
Pesticide Recertification credits in Core, Cat 1 & 2.

Registration is due by February 19.
Call Mike Hogan at the Carroll County Extension office at 330-627-4310 for more information or call your local Extension office.

3) ----

Dollars & Sense Agronomy Day
“Dollars and Sense Agronomy School” on February 28, 2007 at the United Food Workers Local 1099 Union Hall at 913 Lebanon Street in Monroe Ohio sponsored by OSU Extension in Warren, Clermont, Preble, Montgomery, Clark and Butler Counties. Producers and industry people alike will gain valuable information to make their production techniques more profitable in the coming year.

For $30.00, participants receive refreshments, buffet lunch, handouts, an OSU agronomy publication, CCA credits and Commercial Applicator Credits.

Registration is due no later than February 19th, 2007.
Guest OSU speakers include
• Barry Ward, Leader from Production Business management,
• Bruce Eisley, Research Associate from Entomology,
• Jeff Stachler, Program Specialist from Weed Science,
• Jonah Johnson, Clark County AgNR and
• Robert Mullen, Extension Soil Specialist.

The day is full of valuable information for all farmers and producers looking to save money in 2007.

Registration sent to 1810 Princeton Rd., Hamilton, OH 45011 or call 513-887-3722.

Archive Issue Contributors: 

Peter Thomison (Corn Production), Anne Dorrance, Pierce Paul and Dennis Mills (Plant Pathology), Robert Mullen (Soil Fertility), Ed Lentz (Agronomy), Ron Hammond and Bruce Eisley (Entomology) and Mark Loux (Weed Science). Extension Agents: Roger Bender (Shelby), Howard Siecrist (Licking), Todd Mangen (Mercer), Mark Koenig (Sandusky), Mike Gastier (Huron), Glen Arnold (Putnam), Keith Diedrick (Wayne), Jonah Johnson (Clark), Harold Watters (Champaign), Alan Sundermeier (Wood), Wesley Haun (Logan), and Greg LaBarge (Fulton).

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.