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4 Tips for a Soybean Switch

08:26AM Jan 03, 2015

Taking fields out of corn-on-corn? Consider this advice

Have you been engaged in a corn-on-corn rotation for the past several years but are interested in switching acres back to soybeans? Andrew Ferrel, a Mycogen Seeds agronomist, has four helpful pointers to share:

1. Start with a clean field. It takes time to break down corn crop residue. That can create a barrier for young soybean seedlings, especially under reduced-till or no-till conditions. Residue also keeps springtime soils cool and wet longer, which creates an ideal environment for certain fungal pathogens.

“Soybean yields are highly affected by poor emergence and early vigor,” Ferrel says. “It is important to get soybeans off to a good start with an even and well-established stand. In some cases, light tillage of heavy corn residue may be needed to create a clean seedbed for good seed-to-soil contact.”

2. Head off emergence issues with a combination insecticide and fungicide seed treatment. Ferrel says the 
investment is worth the minimal added expense to help promote a strong stand, especially when planting in less than ideal conditions.

3. Consider soil inoculants. Corn-on-corn production can reduce levels of Bradyrhizobium japonicum, the soil bacteria that fixes nitrogen (N) for soybeans. If you have fields that have been out of soybean rotation for four or more years, Ferrel says adding an inoculant will ensure proper nodulation and prevent the need for supplemental N applications.

4. Watch nutrient levels. Corn removes significant amounts of nutrients from the soil, especially N, phosphorus (P) and potassium (K). Additionally, N applications in corn can affect the soil’s pH. Therefore, it’s important to test for N, P, K and soil pH before planting soybeans in order to make any necessary adjustments.

Aaron Saeugling, a field agronomist with Iowa State University, says a soil analysis is the first step a farmer should make before swapping crops.

“If you want to get fertility to where it needs to be, it’s hard to know where that is without testing,” he says.

As farmers plan for 2015 planting, they should assess fields to determine which are best-suited for soybean production. Although Saeugling suspects many farmers consider soybeans a secondary crop, he says a little extra care in management, such as variety selection, could really pay off.

“The mistake I see most is when farmers only plant one or two varieties of beans across all their acres,” he says. “They try to find one that fits all of their needs instead of investigating how to jump out on soybean yields.”

Rotating a field from continuous corn to soybeans is an agronomic and economic decision. “When evaluating the rotation choice, it is important to remember the differences in yield and cost of production,” says Michael Duffy, retired economist with Iowa State University. “Evaluate the entire rotation, not just single years within the rotation.”

According to the University of Illinois, the soybean-to-corn price ratio averaged 2.20 from 1999 to 2013 and 2.40 from 1972 to 1998. 

Duffy encourages farmers to also look at long-term tillage strategies and environmental factors.