Even if your planter is equipped to apply starter, should you still apply it if planting is delayed later into the spring? A one-year study at the Precision Planting Institute near Pontiac, Ill., operated by Precision Planting, indicates the better parameter might be weather, including soil temperature, rather than the calendar.

Jason Webster, who manages PTI, reports that they planted April 5, April 11, April 23, May 14 and May 23 in the planting date vs. starter fertilizer comparison in 2020. They also compared five different types of starter fertilizer and two different application systems off the planter, Furrow Jet and Conceal, both offered by Precision Planting. Then results for starter vs. no starter were averaged together at each planting date.

Starter fertilizer delivered a yield boost at every planting date, Webster reports. The yield increases per acre for the five dates for starter fertilizer vs. no starter were 23.8, 18.5, 11.0, 19.2 and 6.0, respectively.

“It was cool early, and then we had a cool stretch in mid-May,” Webster recalls. “It was warmer after we planted on April 23, and it warmed up around the time we planted the last corn in the trial on May 23.”

When you look at net returns over cost, the results were slightly different, Webster acknowledges. The first four planting dates delivered a positive return on investment, but the final date did not. Extra return over cost for starter fertilizer for the five planting dates per acre were $56.60, $36.85, $8.65, $39.42 and a −$10.03, respectively.

Note that for both yield and ROI, starter fertilizer was far more helpful for the early April and mid-May planting than even for the late April planting. Weather in 2020 played a key role in the results, Webster believes.