Farmers Face Crop Rotation Quandary

Farmers Face Crop Rotation Quandary

What are you planning for crop acreage mix in 2013? Will you plant more corn or more soybeans?

In last week's edition of Farm Management Friday, headlined "Drought Hangover To Continue," Iowa State University Extension farm management specialist Steve Johnson discussed how memories of the 2012 drought will likely affect farmers' decisions regarding number of acres of corn and soybeans to plant in 2013, and the mix of those acres. In this week's article, Johnson presents additional considerations for farmers to think about as they formulate planting plans and crop rotations.

CORN OR BEANS?: Crop rotation decisions are being made as harvest 2012 is winding down. Farmers will apply fertilizer, do some tillage. And wonder if it will rain enough this fall and next spring to replenish subsoil moisture supply for 2013 crops.

With the summer drought pushing crops to maturity faster than normal, Iowa's 2012 harvest is headed toward finishing earlier than usual. Looking to next year, the question is: Will you plant more corn or more soybeans in 2013? Farmers are laying plans now, starting to make crop rotation decisions. Fertilizer will be applied this fall on many fields. If nitrogen is applied, those fields will be planted to corn next spring.

There are weather concerns. Will it rain enough this fall and next spring to fully replenish subsoil moisture reserves for 2013 crops? Farmers are being encouraged by agronomists to skip tillage this fall or at least cut down on the amount of tillage, to help save precious soil moisture. Also, managing crop residue is paramount; as many of this year's cornstalks are being baled, chopped and tilled.

Memories of drought will likely affect planting decisions
Preliminary surveys show Iowa farmers are expected to plant a total of 23.5 million acres of corn and soybeans next spring. Johnson expects Iowa will see an increase in soybean acres, as enough soybeans will go into the ground so the state's soybean acres will challenge the record 9.8 million acres planted in 2010.

Chances are Iowa and the Corn Belt won't likely plant as many acres of corn in 2013 as in 2012. Why? Johnson refers to what he calls the "drought hangover." Memories of widespread drought in 2012 are lingering in people's minds. Farmers saw cornfields dying early and regret that they didn't plant more soybeans. Also, many farmers want to get their crop rotations back in balance after planting more corn-on-corn in recent years.

More farmers want to move away from planting so much continuous corn
Farmers have planted a higher percentage of Iowa's corn-soybean acreage to corn in recent years. It has trended above 50% corn-50% soybeans. Since 2008, the annual corn-to-soybean planted acreage percentage in Iowa has run between 56% to 60% favoring corn, notes Johnson. That percentage for the nation, by the way, is slightly less, at 53% to 56%. He believes these percentages for Iowa and the U.S. will decrease in 2013 as more soybean acres will likely be planted.

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Several factors have attracted a higher percentage of land into corn production in recent years. Those include improved corn genetics, along with more disease and pest challenges in soybeans. New types of tillage equipment can handle corn crop residue more easily than in the past. And crop insurance considerations have favored corn. Higher cash rents also tend to favor planting corn, notes Johnson, as farmers try to capture higher net revenue potential offered by corn.

But soybean prices have recently moved higher, which helps favor soybean planting next spring. South American weather concerns following the U.S. drought this summer ran soybean prices to record highs by early September.

Lack of subsoil moisture and memory of 2012 drought weigh heavily
Regarding the corn or soybean decision farmers must make for 2013 planting, Johnson says, "Farmers need to evaluate their own individual circumstances. That includes everything from land costs to crop rotation issues to corn and soybean price expectations. I think the lack of subsoil moisture and the drought experience of 2012 will weigh heavily on farmers' minds in making 2013 planting decisions."

To help farmers evaluate profitability for their own operation, ISU Extension has a decision tool available on the Ag Decision Maker site www.extension.iastate.edu/agdm. The online worksheet is A1-80 and is titled "Evaluating Profitability of Crop Rotations". It provides sample figures and formulas farmers can use to insert their own numbers and determine the potential profitability of their crop rotation comparisons.

Using the online tool "Evaluating Profitability of Crop Rotations"
This online tool offers a Rotation Profitability Calculator to plug your numbers into. "While factors like better crop insurance products have removed some of the financial risk in case you have a crop failure, there are other things to think about when deciding your crop rotation," adds Johnson. "The guaranteed revenue provided by crop insurance may be higher for corn than for soybeans, but farmers must consider that it costs more to grow corn, plus there are other factors that can make corn on corn less rewarding than you might think."

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Rather than comparing a year of corn production with a year of soybean production, farmers should look at a two-year period for corn on corn and a two-year period for a corn-bean rotation. "You need to factor in the additional expenses and yield risk associated with corn on corn," says Johnson. "You may do better with a corn-soybean rotation than with corn on corn. Many farmers are and that's why they stick with a corn-soybean rotation."

Other considerations with corn-on-corn vs. corn-soybean rotation
Some of the other key considerations with corn on corn are noted by ISU Extension agronomist Roger Elmore: Do you have a yield drag when you plant corn after corn? Can you control corn rootworm populations? Can you manage corn diseases?

Rootworms and diseases are trickier to manage in continuous corn. What about yield drag? Over the years most farmers in Iowa who grow continuous corn do see it yield less compared to corn grown in a corn-soybean rotation. How much less depends on the year. The yield penalty for corn on corn may range from 0% to 20% to 30% less. In a drought year like 2012 there can be severe loss.

Rootworm populations build up in the soil when corn is grown two years or more, consecutively in the same field. Regardless of whether or not the corn hybrid contains a Bt rootworm control trait, farmers run the risk of building up rootworm populations with corn on corn. If it is a Bt corn hybrid that is grown, the risk includes development of a Bt-resistant rootworm population.

For corn diseases, keep in mind that the strategy for managing them effectively includes three parts: growing disease resistant corn hybrids, rotating crops and managing the crop residue. With corn on corn, farmers are missing one of those key fundamentals.

For farm management information and analysis go to ISU's Ag Decision Maker site www.extension.iastate.edu/agdm and Extension farm management specialist Steve Johnson's site www.extension.iastate.edu/polk/farmmanagement.htm.

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