The next step is making the most of the varieties you choose. “We know variety selection is most important when combined with fertility and row spacing,” notes Below.

Today’s high-powered soybean varieties demand more phosphorus than many people expect. A 70- to 80-bushel-per-acre soybean crop can draw as much phosphorus out of the soil as a 150-bushel corn crop, he explains. Don’t be fooled into thinking that last year’s P application before corn is guaranteed to meet your soybeans’ needs, Below cautions. The huge volume of residue from a hefty corn crop can tie up more than 20 pounds of phosphate and more than 100 pounds of potassium.

The bottom line: Choose good varieties, and give them the nutrients they demand.