Soybean Production in Mississippi
Besides germination and vigor, what else may effect final plant population?
Soil conditions - Cloddy, crusted, or dry soil will usually reduce emergence. Soil temperature should be within a range of 68 to 86º F at the desired planting depth for the fastest and greatest percent emergence.
Seed treatments - Fungicides may increase emergence of lower quality seed, especially under less than ideal soil conditions. Seed with 80 percent or higher germination may be affected slightly, if at all. A fungicide containing the active ingredient metalaxyl may prove beneficial for early planting. Remember, seed treatments with fungicides may increase stands, but rarely increase yields as long as final stands are uniform and within the desired range. Seed treatments are a form of insurance. Sometimes they pay, sometimes they do not. Cropping history, soil temperatures, and the five-day weather forecast following planting will all aid in this decision.
Depth of planting - Plant soybeans 1 to 2 inches deep, depending on the soil type and the moisture situation. Deeper planting slows emergence and may reduce final stands. Place seeds in firm, moist soil and cover them adequately. Soybeans must absorb 50-55 percent of their weight in water to germinate, so good seed-to-soil contact is critical.
Herbicides - Many herbicides can affect stands and seedling vigor if rates are excessive or if there is excessive rainfall and otherwise poor growing conditions.
Cultivation - Cultivation in row middles should not affect stands. Rotary hoes are effective in breaking a soil crust and removing small weeds. However, stand losses may occur if you operate hoes in the morning hours when small seedlings are brittle.
For additional information see Mississippi State University Extension Service Publication 1194 Soybeans: Plant Populations and Seeding Rates.