Impacts of Heavy Rains on Soybeans

April 30, 2024

In spring and fall, heavy rains are common and can occasionally result in saturated and even flooded soybean fields.  At such times, plants are more susceptible to delayed emergence and slower growth, in addition to being at greater risk of disease.

In this article, we explore the factors that influence rainfall impacts on soybeans, as well as different strategies to minimize the damage!


Soybean crops suffer less damage from short-term floods than floods that persist for many days. Here are the different effects that are possible based on duration:

  • Less than 48 hours

Usually, there is no yield loss.

  • 4 days

Plants may experience delayed growth, for instance be shorter and have fewer nodules.

  • 6 days

There is a risk of yield loss.

  • 7 days or more

There is a risk of considerable, even total, crop loss.


Weather is an element that plays a crucial role in soybean crop survival after flooding. Higher air  temperatures stimulate respiration in plants and soil microbes. This speeds up oxygen use, increasing CO2 levels, to which soybean plants are especially sensitive.

In the opposite case, cool, cloudy weather improves soybean survival by using less energy and oxygen.

Soil type and field drying

During one flooding event, researchers noted that yield losses were greater in flooded clay soils than in silt loam soils. In fact, during the V4 growth stage, losses reached up to 1.8 bu/ac per day on a clay soil, compared to 0.8 bu/ac on a silt loam soil.

Growth stages

The effects of flooding in soybean fields tend to be considerably higher during the later reproductive stage. The closer it is to harvest time, the greater the potential damage. Damage may include stem breakage, lodging, pod splitting or premature seed sprouting.

Management options

After flooding, the condition of the fields can be assessed within 3 to 5 days after the waters recede. More specifically, examine auxiliary buds for growth points, but also assess the density of the surviving plants and check seedlings for diseases such as Phytophthora.

If stands are sparse, replanting may prove a good option. However, keep in mind that the plants will remain stunted and yellow until nodulation increases, and conditions can evolve quickly after several days of fine weather.

And there you have it! Now you know a little more about the impact of heavy rains on soybean yields. We hope you enjoyed reading this article!

Sources :

University of Minnesota. (2018). Field drying and soil type.

Informa markets. (2019). Early-season flooding impact on corn and soybeans. Early-season flooding impact on corn and soybeans (

RAP. Grandes cultures. (2023). Grandes cultures avertissements No 12.

Bohner, H. (2016). Flood damaged soybeans.