David Moseley and Boyd Padgett, LSU AgCenter Scientists
Article Highlights:
- Heavy rains stall soybean planting
- Target a soybean stand of 70,000 to 75,000 when considering if additional plants are required
- A few management tips for flooded fields
Planting Progress and Delays
Louisiana's soybean planting progressed well in mid-April, exceeding the five-year average. However, heavy rains in mid-May slowed progress, with only 69% planted by May 12th, 2024. This lags behind last year's 76% at the same point. An article, “The Farmer's Forecast: More Soybean Planting Delays” indicates continued rain and potential wind/hail threats.
Emergence and Replanting Considerations
Excessive rain has also hampered emergence. LSU AgCenter researchsuggests a final soybean stand of at least 70,000-75,000 plants per acre is adequate for achieving 95% yield potential.
Flood Impact on Soybeans
Flooding and saturated soil conditions can significantly damage soybeans. The severity depends on plant growth stage, flood duration, and other environmental factors.
- Soybean Sensitivity: Plants become more vulnerable to flooding as they reach the R3 (pod development growth stage).
- Flood Tolerance: Depending on temperature, soybeans may withstand flooding for 2-3 days.
- Oxygen Depletion: Flooded soils lose oxygen, especially in hot weather, harming plant and microbial respiration.
- Photosynthesis Reduction: Debris covering leaves after a flood can reduce yield by limiting photosynthesis.
Managing Flooded Fields
- Drainage: If possible, clear obstructions in ditches or furrows to promote drainage.
- Traffic Control: Limit unnecessary traffic on saturated fields to prevent soil compaction.
- Foliar Applications: Reduce applications that can burn leaves after flooding.
- Scouting and Monitoring: Continue scouting for pests and assessing nitrogen-fixing nodule activity. Floods can temporarily reduce nodule activity, but it may recover afterward.
Soybean Flood Tolerance Varieties
The LSU AgCenter collaborates with universities to develop flood-tolerant soybean varieties. Data from 2023 flood trials is available in the 2024 Soybean Variety Yields & Production Practices. Similar trials are planned for 2024.
Figure 1. Soybean plants in flooded conditions due to excessive precipitation.
