What to Consider
Soybeans can be at a variety of growth stages during midseason. Partially submerged plants have an increased chance of survival compared to completely submerged soybean plants. Water-logging, where roots are flooded without plant submergence, is also common. Several factors influence potential soybean damage:
- Growth stage during flooding/ponding
- Length of time plants were flooded/ponded
- Temperature (soil and air)
- Drying rate and soil type
Yield loss results from reduced root growth, shoot growth, nodulation, nitrogen (N) fixation, photosynthesis, biomass accumulation, stomatal conductance, and plant death from disease and physiological stress.
Soybeans completely submerged for 48 to 96 hours generally survive.1,2
Flooding for four (or more) days delays plant growth, shortens plants, and reduces node number.
Flooding for six days or more is expected to have a negative effect on yield.
· A week of flooding may result in significant or 100 percent stand loss.1
· Wide range of yield loss may be experienced depending on environmental conditions and soil types (Table 1). In cooler temperatures, submerged plants are expected to live longer with slowed respiration. Warm temperatures increase respiration and oxygen is consumed quickly.3
· Potential soybean yield loss from water-logging could be 17 to 43 percent during vegetative stages and 50 to 56 percent during reproductive stages.2
· Presence of soil borne diseases and differences in soil texture affect the response of plants to flooding.