In years past, I would answer this question, with a shrug and say, “Oh an inch or so… ”
The last couple years I’ve told many of you to leave the drill at the same depth from wheat to beans, implying that 1.5-2 inch mark.
Thoughts around Soybean Planting Depth:
*Soil moisture conditions – Where is the soil moisture consistent? Soybeans require 50% of their weight in water to germinate, so ample moisture is critical. Planting deeper (closer to 2″) gives more consistent moisture. I’ve found in shallower planted soybeans, while they do emerge more quickly, they also express drought symptoms faster when we get into the long, hot days of summer, ultimately aborting pods and affecting yield.
*Soil texture – Sandy soils have a greater fluctuation of soil temperature in the early planting days, furthermore promoting a deeper planting depth (closer to 2″), for a more consistent soil temperature buffer. Loamy/finer soils will have more stable soil temperature and planting depth can be shallower (1.5″) with good success.
*Residue – If soils have heavy residue, planting depth should be closer to 1.5″. Residue holds moisture in the soil and generally keeps the soil cooler in temperature.
Bottom Line: 1.75″ planting depth is where its at for soybeans!