Evaluating The Effects Of Extreme Weather Conditions On Louisiana Soybean Development And Yield In 2026
DAVID MOSLEY
BATON ROUGE, LOUISIANA
The 2026 Louisiana soybean growing season included several weather extremes that may affect yield. The amount of any yield loss will be difficult to determine until harvest because crop response varies with growth stage, soil type, drainage, irrigation, and other management practices. In addition, statewide and regional weather summaries do not capture the conditions experienced in every field.
Four major weather-related events or patterns affected Louisiana soybean production during 2026: a freeze on March 17, above-average temperatures during March and April, excessive rainfall and flooding during May and June, and hot and dry conditions in July and August.
Figure 1 shows that 75% of the Louisiana soybean crop was planted by April 25, approximately 13 days earlier than the five-year average date of May 8. This early planting probably contributed to the earlier occurrence of subsequent developmental milestones. Statewide, the 75% dates for beginning bloom, pod set, and beginning color occurred approximately 11 to 14 days earlier than their respective five-year averages. Above-average maximum and minimum temperatures during March and April may have further accelerated soybean growth and development (Figure 2).
The March 17 freeze damaged some of the earliest-planted soybean fields in Louisiana. Observed injury included damage to unifoliate leaves and the apical meristem. However, many affected plants recovered by producing axillary branches from lower nodes. The statewide impact of the event was limited because only approximately 1% of Louisiana soybean acreage had been planted when the freeze occurred.
Excessive rainfall during May and June created saturated soil conditions in many fields and caused severe flooding in portions of central Louisiana (Figure 2). Rainfall associated with Tropical Storm Arthur was especially intense in the central Louisiana region, where approximately 30 inches of rainfall in less than 12 hours was reported. Preliminary assessments indicated that approximately 114,000 soybean acres were affected by the flooding. Nearly 38,000 acres were considered complete crop losses, while persistent wet conditions prevented the planting of an additional 15,000 acres. Many surviving fields experienced partial stand loss or other injuries that could reduce yield and profitability. Total economic losses to Louisiana soybean production were estimated at approximately $33 million, based on an LSU AgCenter damage assessment.
Nighttime temperatures during June and July were generally above their recent averages. Warm nighttime conditions can increase plant respiration and the use of carbohydrates produced through daytime photosynthesis. This inefficient use of energy by the plant can reduce yield; however, the effect of the higher-than-average temperatures could have been mitigated by the adequate soil moisture by supporting transpiration and evaporative cooling. Therefore, frequent rainfall during May and June may have moderated heat stress in fields with adequate drainage. In poorly drained or flooded fields, however, the benefits of available water were likely outweighed by oxygen deficiency and impaired root function. Heat and saturated soil conditions can interact because warm temperatures increase plant and microbial oxygen demand in already oxygen-limited soils.
In July and August, rainfall was below and the maximum temperature was above the 2020–2025 average in Chase and Alexandria, LA. The potential consequences of higher heat and drying pattern differed among fields because soybean development was early in 2026. Soybeans planted during the early and middle portions of the recommended planting window were generally farther along in seed fill or beginning to mature, whereas later-planted fields could still have been at growth stages that were more susceptible to heat and drought stress. ∆
DAVID MOSLEY
LSU AGCENTER