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David Moseley, LSU AgCenter Soybean Specialist
The United States Department of Agriculture (USDA) National Agricultural Statistics Service (NASS) estimates Louisiana farmers will plant 1.05 million acres of soybean in 2025. This estimate is down 5% from 2024.
By March 30th, farmers had planted 6% of the Louisiana soybean crop which is 2% more than the 5-year average, according to the USDA-NASS.
Figure 1. Soybean acres in Louisiana from 2006 – 2025 according to USDA-NASS.
Soybean plants, despite their high nitrogen requirement, typically don't need nitrogen fertilizer applications due to their symbiotic relationship with Bradyrhizobium japonicum bacteria. These bacteria fix atmospheric nitrogen into a plant-available form. Inoculation with Bradyrhizobium japonicum is crucial in fields with no recent soybean history. However, even in established soybean fields, research has indicated inoculation can increase yield at least slightly. Successful nodulation, and thus nitrogen fixation, can be negatively impacted by factors like extreme temperatures, soil pH imbalances, salinity, waterlogging or drought, nutrient deficiencies, and high soil nitrogen levels. To assess active nodulation, farmers should examine nodules during early vegetative growth (V1), with nitrogen fixation beginning around V2 - V3. Healthy, active nodules will exhibit a pink to red interior. If nodulation is inadequate, a corrective nitrogen application may be necessary. This information is from the fact sheet, “Soybean Inoculation and Nitrogen Fixation,” produced by the Science for Success team, a collaboration of university Extension soybean agronomists, and funded by the United Soybean Board. For specific management recommendations on soybean inoculum, refer to the Oklahoma State University article, Management of Soybean Inoculum.
Funded by the United Soybean Board, the Science for Success team published a fact sheet, “Biological Seed Treatments on Soybean,” detailing a nationwide trial of various biostimulant seed treatments. The trial revealed no significant yield improvements. Potential reasons for this include unfavorable environmental conditions, inactive microbes within the treatments, or competition from native soil microbes. The fact sheet emphasizes that the study included only a selection of available products, and that proper handling and application are crucial. It recommends farmers collaborate with university Extension for on-farm testing of products.
Soybean plants can achieve maximum yield across a range of plant populations. The LSU AgCenter's 2025 Soybean Variety Yields and Production Practices publication recommends a final stand of 78,000 to 130,000 plants per acre under normal situations. Because not all planted seeds germinate and thrive, the initial seeding rate must exceed the desired final population. Factors like cool, wet, dry, or crusted soils can hinder emergence and reduce plant productivity. For detailed information on low plant stand causes and replanting decisions, consult the recent Crop, Forage, and Turfgrass Management journal article, "Low soybean plant population: Is replanting necessary?"
