Field Management of High Oleic Soybeans for Feed

Introduction

As high oleic soybeans become more available in Wisconsin, growers are interested in how these soybeans can improve the economics on their farm. Local markets commercially selling these soybeans at a premium price are developing, as much of the interest in high oleic soybeans in Wisconsin is centered around the dairy feed industry.  

High oleic soybeans have a fatty acid profile that allows higher feeding rates without depressing milkfat production compared to conventional soybeans. This means more ingredients for the ration can potentially be produced on the farm, reducing feed costs for dairies.  

Nonetheless, there is still a lot to learn. Farmers should consider the stewardship and in-season management of high oleic soybeans required to maximize their benefits prior to purchasing seed to ensure they are the best option for the farm. 

Identity preservation systems for high oleic soybeans

Before committing to growing high oleic soybeans, plan out the logistics needed for identity preservation (IP) systems to ensure they are a feasible option and good fit for the farm. These systems have two purposes: to ensure the quality parameters of the high oleic soybeans are not reduced by mixing with standard soybeans, and to avoid contamination in the export market.  

GMO high oleic varieties require a “soft” IP process which means managing quality control throughout the supply chain from planting and harvesting to transport and storage. Key steps in the process include marking where high oleic soybeans are being grown in the field and equipment cleanout processes.  

Non-GMO high oleic soybeans require a “hard” IP system, which has more thorough cleaning procedures for equipment and additional product testing to verify that there are no GMO traits present (Sanders 2024). Specific guidelines for either IP system are typically stated in a production contract when the grower buys the seed.  

IP systems still apply to growers who intend to use these soybeans for their own animal feed. Farms with on-site storage, roasting, and crushing have more control over the entire process, which may be an advantage. If the high oleic soybeans will be transported to a feed mill for storage, roasting, crushing, and returning to the farm, that facility will need to be approved by the company that the seed was purchased from to ensure they have the capacity to handle another type of soybean and will be following IP processes. This may take some time if the facility is not already approved to handle the product, so give yourself ample lead time to plan before signing a contract and making seed purchases. 

Weed management for high oleic soybeans

There are several different herbicide resistance packages to watch for as new varieties of high oleic soybeans hit the market, and they may not match up with current herbicide programs being used on your farm. Many of the varieties available at the time this article was written are conventional, while others are only glyphosate-resistant. In the coming years as more varieties are developed and become more widely available, more trait offerings will be available such as 2,4-D and glufosinate resistance.  

Pay close attention to the trait packages you are purchasing and plan a separate herbicide program if necessary. Mark fields where high oleic soybeans are being grown and communicate that information with any custom applicators to ensure there are no incorrect product applications.  

Herbicide-resistant weeds such as waterhemp and giant ragweed can pose problems given the limited herbicide resistance traits initially available. Choose fields that have less weed pressure and invest in preemergence soil residual herbicides to prevent troublesome weeds from germinating. When there are few postemergence herbicide options for your soybeans, weed prevention and prompt application are critical.  

A two-pass herbicide system, preemergence followed by a timely postemergence application, is typically required for effective weed control in Wisconsin soybeans. Weeds need to be less than 2” tall at the time of postemergence application for herbicides to perform adequately. Remember, herbicide options are limited in conventional and glyphosate-tolerant soybeans, so there may not be a viable rescue treatment if weeds get out of hand. It is imperative to catch weeds early, which requires frequent scouting.  

For weed control ratings of various herbicides, see Extension publication A3646 Pest Management in Wisconsin Field Crops ↗️ or the most recent Wisconsin Weed Science Research Reports ↗️.  

Crop management for high oleic soybeans

As with any feed ration ingredient, quality is essential for maximizing nutritional value and must be considered alongside overall yield. In addition to typical genetic variation, oil content, protein concentration, and fatty acid composition are all influenced by environmental conditions and planting date (Mourtzinis 2017).  

Early planting (mid‑April to early May) generally increases oil content and supports higher yields, whereas later planting tends to increase protein concentration (Mourtzinis 2017). Planting date also affects the fatty acid profile: early planting was associated with higher oleic acid and sugar content. However, because this information was originally collected from soybeans that were not high oleic soybean varieties, it remains unclear how these traited varieties will translate under on‑farm conditions.  

Monitor and track protein and oil levels in soybeans produced on farm to ensure the product meets the quality standards needed for its intended purpose while yielding enough to be profitable. If standard soybean planting timing doesn’t result in the desired oil or protein content of your product, consider adjusting planting date. Planting earlier may warrant a more aggressive weed control program 

As with other soybean varieties, the basics of soybean management still apply. Avoid poorly drained fields and compacted soils, and use rhizobia bacterial inoculants at planting if soybeans have not been in the crop rotation for 5+ years. If soybeans have been in rotation recently, there is marginal benefit to adding inoculant.  

Managing diseases will also be necessary in high oleic soybeans. Be sure to consider past disease history in the fields you plan to grow high oleic soybeans and plan for your management program. White mold remains one of the most important soybean diseases in Wisconsin. Be sure to adjust seeding rates (down to 120,000 seeds per acre) at the time of planting in fields with a history of white mold. In-season fungicide applications around R2 or R3 growth stages may be necessary. Be sure to factor the cost of a fungicide application into the decision to grow high oleic soybeans.  

Finally, soybean cyst nematode (SCN) remains one of the most important soybean pests in Wisconsin. Be sure to choose a variety with an effective SCN trait to minimize yield losses due to this pest.  

Mycotoxins in high oleic soybeans

Soybeans tend to be less prone to mycotoxins compared to corn and other grain crops, but they should still be tested when being used for feed (Rodrigues and Naehrer, 2012). In Wisconsin, it is extremely rare to find high levels of mycotoxins in soybeans produced in the state. However, in rare cases it is possible and should be monitored. High levels of zearalenone, deoxynivalenol (vomitoxin), and aflatoxins have been documented in some soybean meal samples from North America (Rodrigues and Naehrer, 2012).  

Mycotoxins are very heat stable, so roasting does not eliminate the problem. The best way to prevent mycotoxins in soybeans is to keep plants healthy and prevent physical damage to the pods and seeds. This type of damage can by caused by insects, such as stink bug and bean leaf beetle, and creates a direct point of entry for fungal pathogens like certain strains of Fusarium spp. and Aspergillus spp (Piotrowska 2013).  

Always be sure to test soybean meal and the total mixed ration for mycotoxin levels. The only way to know how much mycotoxin is present is to have it tested by a reputable diagnostic lab.  

Authors

Jordyn Sattler
Regional Crops & Soils Educator
University of Wisconsin–Madison Division of Extension

Shawn Conley
Soybean & Small Grains Extension Specialist, Professor
University of Wisconsin–Madison Division of Extension