Growers often plant soybeans at populations much higher than necessary for optimum yields. Reasons cited for this often include such things as that the extra plants will aid the emergence of their neighbors, or that the extra seed is not really that expensive and it doesn’t seem to hurt. Research has shown that there is usually little reason for planting soybean seed at populations above 150K per acre in 30 inch rows. In fact, there is much research that shows that near optimum yields can be obtained with soybean populations of 100K or less.
When planting soybeans in row widths of 15 inches or less, particularly in heavy-textured soils, it is sometimes beneficial to plant soybean seed at rates between 165K and 220K. This can contribute to more uniform emergence and sometimes to faster canopy closure, though not necessarily to higher yields. In fact, Purdue University recommends planting about 210K seeds per acre in 7 inch rows, 163K seeds per acre in rows spaced between 11 and 20 inches, and 131K seeds per acre in row spacing above 21 inches.
Be sure to check soybean seed bag tags for warm and cold germination percentages, and adjust seeding rates accordingly. When planting soybeans early for your area, a quality seed treatment may provide a slight positive edge for stand establishment.
