Selecting the appropriate seeding rate for a soybean production system can affect optimal yield potential, economical net returns, as well as some negative factors including potential for lodging.
Choosing the optimal seeding rate for a given production system should be based on several factors — desired plant population, soil type, planting date and maturity group.
Other factors that affect optimal seeding rates include roughness of soil, type of planter or drill, percent germination of seed, and in some cases seed vigor. The following criteria and/or situations can be used to help in selecting an optimal seeding rate.
Higher seeding rate situations:
• Planting extremely early (March — early April)
• Heavy clay soils
• Group 3 or early to mid-Group 4 varieties
• Planting with a gravity flow drill
• Rough soil conditions
• Low germination seed
Lower seeding rate situations
• Late planting (late April through mid-May)
• Sandy soils
• Group 5 varieties
• Vacuum planter
• Smooth or optimal soil conditions
• High germination seed (greater than 90 percent germination)
The decision to use a higher or lower seeding rate should be made on a field by field basis. A combination of the factors listed above rather than just one of the listed factors should be considered when selecting an optimal seeding rate. Deviating significantly from your individual comfort zone with respect to your historical seeding rates may result in a final plant population that may not reach optimal yield potential or an excessively thick stand having the potential for lodging.
For detailed information on selecting and calculating a seeding rate, download the pdf file Optimal plant populations/seeding rates for soybeans.