Soybean oil and protein quality

March 3, 2025 | Josh McDanel

Farmers prioritize maximizing yield when producing soybeans, while processors focus on extracting the oil and protein from soybeans.

Soybeans higher in protein and oil have the potential to provide increased revenue in the feed and fuel markets, respectively.

Three factors play a role in soybeans’ oil and protein composition: genetics, management, and environment.

The Iowa Soybean Association (ISA), in collaboration with Kansas State University, received a grant from the North Central Soybean Research Program and United Soybean Board to investigate the factors affecting soybean seed composition. This involved nationwide field sampling to study variations across diverse environments.

From 2019 to 2023, ISA collected soil and plant samples near harvest from 10 to 15 farmer fields in Iowa each year. ISA collected a total of 917 samples from 84 fields (Figure 1).

Oil and protein levels across environments and management practices varied minimally, but demonstrated the current oil and protein concentrations in typical, modern soybean varieties available in Iowa (Figure 2).

Figure 2. Protein (A) and Oil (B) percentages are shown by the region of Iowa they were produced.

Average oil concentration was 21.7% (range of 17.7%-25.1%) and average protein concentration was 37.7% (range of 30.9%-42.4%). Both values are reported on a dry matter basis.

The average protein and oil percentages for U.S. soybeans are 39% and 22% respectively. Latitude played a role in observed protein and oil percentages. Protein percentages were higher in the northern two tiers of the state compared to the southern tier, with the opposite trend being observed in the oil values.

While the trend was consistent, the range in difference was 1.5-2% between regions. Other than latitude, no other environmental conditions in Iowa (e.g., temperature, sunlight, etc.) showed an effect on soybean quality.

A combination of genetics, environment and management factors influences soybean crop growth. This study showed minimal effect of management on oil and protein concentrations. Oil and protein production are subject to each growing season’s variable conditions. Sampling from 2019 to 2023 showed that latitude was the only environmental factor that showed an effect on oil and protein concentrations. Any other variability is likely to have a minimal effect.

The last control method, genetics, offers a viable method for altering oil and protein content. Through targeted breeding programs, varieties have been developed that produce higher concentrations than other varieties. For a plant to produce higher concentrations of protein, it can come at a cost to plant growth and development by redirecting nutrients, resulting in lower yields. The potential tradeoffs between protein and yield led ISA to create an oil and protein economic simulator.

Soybean Quality Economic Simulator

Lost yield and additional input costs are challenges when targeting high protein concentrations in soybeans. To better understand the true impact of the yield loss and additional costs, an interactive simulator was developed to enable estimates of economic outcomes when growing specialty soybean varieties.

Specialty varieties typically have a contract that provides incentives for farmers who grow these soy varieties. These contracts may provide premium payments and other incentives, such as transportation costs of the harvested grain to offset the reduced income from lost yield. The simulator can account for these incentives and possible additional costs such as seed cost, herbicide and various other inputs.

The tool shows a range of return on investment based on the user supplied inputs and the break-even premium required to offset lost revenue and additional costs.

Default values are filled in when opening the simulator and can all be altered to account for unique situations. The simulator is available for anyone to use and can be found by navigating to the ISA website and clicking on the Research tab.

Results are presented for Iowa, but this was part of a larger study across multiple states to better understand oil and protein variability. Continued monitoring of soybean quality traits can help inform breeders on targets that, in addition to yield, help showcase the value of U.S. soy to end users.

Future policies for sustainable aviation fuel and renewable diesel may change the outlook for the value of oil and protein coming from soybeans. Future demand may incentivize growing specialty soybean varieties for specific end users, and it will be important for farmers to evaluate potential return on investment outcomes before making decisions to grow these types of varieties.

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