Soil pH should be above 6.0. Soil P needs to be only 15 PPM or greater for maximum yield. Don't apply nitrogen to soybeans. Because soybean seed is sold in 50 pound units, buy varieties with small seeds to make a unit plant more acres. Use public certified varieties to control seed input cost.
Public varieties yield well and usually have good resistance to disease.
Buy varieties with proven performance that have been around a couple of years rather than the newer, more expensive ones. If they have not been compared to other varieties in a University performance trial, don't take a chance on them. Select varieties with as much disease resistance and tolerance as possible as a means of holding onto yield. Such varieties don't cost any more than susceptible ones. Ohio loses 6 to 12 bushels per acre each year due to disease.