Y*ou were worrying about soybean rust hitting next year, or maybe soybean aphids, and that means reduced soybean revenue and higher production costs.

So you started thinking about replacing soybean acres with more corn in 2007, and suddenly the market tasseled out with $3 prices. That made the decision easier to expand your corn acres next year and stick the seed everywhere: waterways, the pasture, your wife’s garden, even where you grew corn this year. The farm gate can’t repair the damage with the first three, but let’s consider some risk management for your second year corn.

Every Cornbelt farmer planning corn after corn in 2007 will be helped by a visit to Purdue’s Corny News Network. Agronomist Bob Nielsen and Purdue colleagues Bill Johnson, Christian Krupke, and Greg Shaner have identified about all the known agronomic risks to second year corn. While most farmers express satisfaction with the yield performance of continuous corn, the Purdue staff says their Cornbelt colleagues researching corn after corn indicated an average yield loss of 9% for continuous corn, with yield losses ranging from 2 to 23%. Of 26 studies reviewed, only two cited yield advantages to continuous corn. If you know the potential problems, then you can create a risk management plan to address those.

Problem #1: Crop residue.

With 180 bushel corn, about 10,000 pounds of residue per acre is left in the field, and the yield drag increases as tillage decreases. The causes for that include: “1) greater levels of disease inoculum, 2) cooler, wetter soils during or after planting, 3) interference w/ planter row units, 4) wetter soils during or after harvest, and 5) decreased efficacy of soil-applied herbicides.”

Solutions: Spread the residue with stalk choppers, use tillage where practical, avoid planting on prior rows, use planter attachments for better seed placement, consider strip tillage, and select hybrids that do well in a cold, wet, risky environment.

Problem #2: Nitrogen fertility.

Continuous corn will require 30-50# of additional nitrogen, since the intervening soybean crop was not planted. With more corn acres nationally, nitrogen prices will rise with the demand.

Solutions: Budget for increased nitrogen volume, higher nitrogen costs, and increased time to apply the nitrogen to your increased corn acreage. Alternative application methods may be considered because of plant-height restrictions.

Problem #3: P and K fertility.

Corn takes up more phosphorous and less potassium than soybeans.

Solutions: Although year 1 will not be a problem, there will be adjustments needed in P and K availability over time. Potassium monitoring will be important for stalk strength.

Problem #4: Stand establishment.

Any soil that is poorly drained will be slow to dry out and warm up to allow timely germination and provide a nurturing environment for a young corn seedling. Exposure to disease and insects is exacerbated if growth is slowed.

Solutions: Select hybrids with superior emergence and seedling vigor. Plant second year corn in your better drained soils. Consider the use of planter attachments or strip till to upgrade the soil environment, and also consider the use of starter fertilizer and soil insecticides or seed treatments.

Problem #5: Disease risk.

With multiple year corn in the same soil there are increased chances for gray leaf spot, northern corn leaf blight, stalk rots and ear rots generated by fungus sustained by continuous corn.

Solutions: Consider burying prior crop residue along with the fungus innoculum to reduce the chance for diseases. However the priority should be selection of hybrids that have resistance to such diseases that spring and summer weather may or may not foster.

Problem #6. Insect risk.

Although some parts of the Cornbelt have rootworm variants that thrive in corn-soybean rotations, other parts of the Cornbelt still benefit from soybeans that have the capability of reducing the impact that rootworms would have on continuous corn. Additionally, there will be an increased population of wireworms, seedcorn maggots, white grubs and slugs that will decrease your seedling population.

Solutions: Purdue staffers suggest you “Mitigate the insect risk in second-year corn by the judicious use of soil-applied insecticides, insecticide seed treatments (high rate formulations), or transgenic resistance (Bt-rootworm) for rootworm.” Increase crop scouting to look for increased problems from armyworms.

Problem #7. Hybrid selection.

With all of the checklists you have collected so far, you will have to find a high-yielding hybrid that meets all of your requirements. Your neighbors will be looking for the same characteristics, and you will find its availability will either be limited or worse.

Solutions: Expand your normal search for hybrid seeds, which may include adjacent states, companies from which you are unfamiliar with the territory reps, and look for data from university variety trials.

Problem #8. Weed management.

You will have fewer herbicides to use, since soybean herbicides will not be in your rotation in those continuous corn fields. There will be increased issues with annual grasses and Johnsongrass.

Solutions: Soil-applied herbicides should be used at full strength, and post emergent herbicides should be applied when weeds are under 6 inches. Shifting atrazine use from preplanting to postemergence will extend the residual window of activity and reduce late season weed emergence. “Mitigate the risk of yield loss due to late postemergence herbicide treatments by using residual herbicides at planting and making postemergence treatments before the V3 stage of corn growth. Mitigate the risk of glyphosate-resistant weeds by including a variety of herbicide modes of action, especially on weeds that are most problematic for control with glyphosate alone. If glyphosate-resistant corn was grown in a particular field in the previous year, one should also strongly consider using herbicides with other modes of action to prevent additional selection pressure for glyphosate-resistant weeds.”

Problem #9. Harvest issues.

With more corn to harvest in the fall of 2007, there will be more demands on machinery and equipment since the number of bushels handled will be increased. Some corn will remain in the field longer than desirable and lodging could be a consequence.

Solutions: Select hybrids that have superior stalk strength, and prioritize your harvest rotation so that weaker corn is harvested first and stronger corn can wait a bit longer. Scout for stalk rots. Consider beginning your harvest earlier than usual, since you will be in the field longer.

Problem #10. Total crop production costs.

Production of more corn acreage means additional expenses in fuel, fertilizer, and any ad hoc crop protectants.

Solutions: Although the Purdue agronomy team did not address the issue of why you are incurring this increased production expense, the farm gate will take the liberty to assume that you are raising extra corn acres for the purpose of increasing your revenue. If you are going to the expense of doing that, you need to lock in your profits from higher valued corn as you incur that expense. A producer who pays higher production costs to gain a higher price, must take advantage of that price or the entire exercise could be futile as the result of a price decline. Your investment will not pay dividends if corn drops below the $3 mark for whatever unforeseen reason.

Summary:

The economics may point to the profitability of increasing your corn acreage, which means second year corn on some fields. That leads to a number of agronomic concerns which could reduce your overall yield and negate the revenue benefits of your decision. However, awareness of the risks and the development of a measured risk management plan will allow you to retain control of your enterprise. Controling the enterprise includes marketing your corn, as well as just producing it!

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