Research HighlightsManaging Double-Crop Soybean Inputs for Profitability
Highlights:
- Using fewer inputs can improve the profitability of double-crop soybeans, though in North Carolina, using select inputs is more profitable than not using any.
- Trials showed that foliar fungicide applications at R3 to protect pod development when disease pressure is building benefit double-crop soybeans the most.
By Laura Temple
Double-crop soybeans aim to boost profit per acre. Most double-crop research focuses on maximizing yield.
However, with the increase in input costs, Jenny Carleo, area grain crops extension agent for North Carolina State University, believes that research also needs to focus on economics.
“Is spending money on some inputs really worth it in double-crop soybeans?” she asks. “This is especially important in double-crop soybeans because the number one yield predictor is planting date, and planting soybeans after winter wheat harvest is outside the ideal planting window.”
With support from the North Carolina Soybean Producers Association, Carleo is investigating the amount of management that should go into double-crop soybeans. Her goal is to identify areas where farmers can trim input costs and boost profitability.
Input Trials
Farmers manage crops with multiple practices. To see what practices profit in double-crop soybeans, Carleo conducted small-plot omission trials in three distinct North Carolina locations, in 2024, 2025 and 2026. Soybeans were planted as soon as possible after wheat harvest. Though planting dates varied, they represented standards for each region.
The experimental treatments included four common management practices for full-season soybeans in North Carolina, with one control using all practices and another using none.
- Seed treatment
- Foliar fungicide at the R1 growth stage
- Foliar fungicide at R3
- Foliar fertilizer containing multiple micronutrients
All treatments were preventative in nature, applied regardless of the presence or absence of pests or signs of nutrient deficiencies. That mimics typical on-farm management of high-input growers in North Carolina.
“So far, we’ve seen interesting trends,” she reports. “The full set of treatments is typically not the most profitable, even if they bump up yields they don’t typically cover the cost. But we’ve also seen that some inputs are better than none.”
Optimizing Inputs for Profit
Though trial data is still being collected and analyzed, Carleo has observed tendencies related to each treatment. She notes that accounting for the cost of the pass for applications must be considered.
“In North Carolina, we don’t recommend using a soybean seed treatment except for early season plantings,” she says. “These trials reinforce that recommendation. Double-crop soybeans germinate and emerge so quickly, even in wet soils, that we saw no yield increase from seed treatments even where there was an increase in plant stand.”
Quick soybean growth compensated for any stand loss. She notes that using an insecticide seed treatment may make sense in fields with a history of pest pressure, but that in most cases forgoing this input cuts costs.
“Foliar fungicide treatments showed more value when applied at R3 rather than R1,” Carleo reports. “LeAnn Lux, assistant professor and our soybean extension pathologist, says disease pressure builds later in the season in our environment. These trials indicate it’s more profitable to protect pod development under heavy disease pressure than at flowering when disease pressure is lower.”
She also notes that trials showed no yield or profit benefit from foliar micronutrient applications in double-crop soybeans, making this another place to save money. This is consistent with previous findings funded in part by the Soy Checkoff.
“So far, our results are leading us to conclude that over management also seems to lead to reduction in seed quality,” she says. “When using all the standard management practices, we saw more purple seed stain, seed damage and lower test weights.”
This research will help farmers decide where spending money is most likely to make money on double-crop soybeans, and where they are better off saving money by reducing inputs.
Additional Resources
Soybean Double-Crop Systems Can Be Improved with Earlier Maturing Wheat Varieties – SRIN article
Improving Profitability, Reducing SCN with a Double-Crop System – SRIN article
Double Cropping Soybean Recommendations in Wisconsin – SRIN article
Foliar fertilizers rarely increase yield in United States soybean – Agronomy Journal paper
Foliar Fertilizers in Soybean Production – North Carolina State Extension, Science For Success video
Foliar Fertilizers Rarely Increase Yield in U.S. Soybean – Science For Success fact sheet
Soybean Foliar Disease Pressure and Fungicide Considerations – North Carolina State Extension article
Meet the Researcher: Jenny Carleo SRIN profile | University profile
The Soybean Research & Information Network (SRIN) is funded by the Soy Checkoff and the North Central Soybean Research Program. For more information about soybean research, visit the National Soybean Checkoff Research Database.
Published: Aug 31, 2026
