The ideal soil for soybeans is loose, well-drained loam. Loam is a mixture of equal parts of sand, clay and silt. This type of soil holds enough moisture to encourage plants to grow and provides nutrients to the soybean roots.
The best soil pH level is 6.5. Always test the pH level of the soil before adding anything to adjust the acidity of the soil. Add limestone to the soil if the pH level is lower than 6.0.
Soil with a high clay content will impede soybean growth. This type of soil becomes waterlogged when it rains and it dries out to form an extremely hard crust. Most clay soil contains low amounts of humus and organic materials needed to nourish soybeans. Amend clay soil with peat moss, organic mulch and sand to add drainage and aerate the soil.