How much residual corn nitrogen is in the soil after harvest?

By Greg LaBarge

I have conducted corn nitrogen rate trials at our Northwest Agricultural Research Center since 1996. The rate range used is 0-240 pounds of N. I was curious about residual N left after corn and started taking total N samples after corn grain harvest beginning in 2016. In those trials, residual N from the zero N plot was around 20 pounds for all years. At the 240-pound rate, the residual N ranged from 40 to 200 pounds, depending on the year. In 2023, I wanted to know how my research station data related to farm fields. Here is a summary of the results.

In the fall of 2023, Extension Educators and our Water Quality Extension Associate Team in NW Ohio took fall soil samples from 21 corn fields in Ohio. Thank you to the farmers who allowed us to sample their fields.

 The average yield was 220 bushels per acre with an average N rate of 187 pounds applied.… Continue reading