Predicted soybean yields across Missouri have declined in recent weeks as a prolonged heat wave reduces soil moisture and increases crop water demand, according to the latest University of Missouri Extension Soybean Growth and Yield Report.
The 2026 yield projections had remained relatively stable until the recent heat wave. With elevated temperatures expected to persist for several more weeks, projected yields could decline further, according to Andres Reis, University of Missouri Extension soybean farming systems specialist who compiles the report.
Declining soil moisture reserves and drought concerns have created challenging conditions across much of Missouri's soybean-growing regions. Northern Missouri has been particularly affected, with the largest predicted yield declines occurring across planting dates and maturity groups.
High temperatures increase soybean water demand and accelerate soil moisture depletion as the crop enters critical reproductive stages. Later April- and May-planted soybeans are moving through stages that have a significant influence on final yield, increasing the potential impact of drought stress.
The effects of hot, dry conditions vary depending on soybean growth stage. MG 4 soybeans planted in April in central and southwestern Missouri are continuing to maintain above-average yield potential.
However, later-planted soybeans moving through reproductive growth could face greater impacts as soil water availability declines. Extended drought during seed fill can reduce pod retention and seed development, resulting in smaller seeds, lower test weights and reduced yield potential.
The Soybean Growth and Yield Report is updated every two weeks to provide information on soybean crop development across Missouri.
The report uses crop growth models to simulate soybean development and yield across different regions of the state. The models incorporate historical and current weather data and are validated using the Soybean Farming System field experiments network.
The report is designed to help farmers assess how seasonal weather conditions are affecting crop development and attainable yield. Its forecasts show whether the growing season is trending above or below average and provide an indication of potential yield outcomes before harvest, supporting in-season management decisions.
Source: University of Missouri Extension, "Soybean yield predictions drop with prolonged heat wave"