• Yield response to starter fertilizer has not been consistently positive in academic trials. We do know that a seed has plenty of N and P to support growth past V1 stage, but some nitrogen in the soil can boost early growth sometimes.
  • Rapid nitrogen uptake doesn’t begin until about June 1 (in Illinois).
  • We can expect more response to starter when planting into cold soils, in corn following corn (residue issues), and when corn’s planted early.
  • “It doesn’t make sense to put starter on your planter just for this year’s conditions, but consider using it if you are already set up for it, if soil temps are below 50 degrees at planting, soil-test P is low (less than 10-12 ppm), and no other nitrogen as been applied to surface soil,” Nafziger says.
  • If soil test phosphorus is low but you don’t use starter, applying DAP before the final tillage will help.
  • Iowa research shows more response to starter fertilizer in soils that are low in phosphorus and potassium to start with (see bar chart).
  • UAN applied on the surface at or after planting can often provide some of the starter effect.