University of Minnesota research refines nitrogen test to boost corn yields

In North Dakota, Agweek reported that a new University of Minnesota research, recently published in the Soil Science Society of America Journal, significantly improves a tool that farmers can use to guide nitrogen application decisions. 

The report noted that too little nitrogen can limit crop yield and reduce profits, while too much nitrogen reduces economic returns on the fertilizer and can lead to environmental degradation, without increasing yield.

That’s why a tool called the Pre-Sidedress Nitrate Test uses soil nitrate status to help farmers determine whether their corn crop may need more nitrogen. By analyzing data from 34 field trials across Minnesota — representing a wide range of soils, weather, and cropping systems — the researchers updated the PSNT threshold.

Researchers found that a reading of 20 parts per million of nitrate in the top 12 inches of soil, measured when corn has four to six fully expanded leaves, reliably delivers 97% of maximum yield.

If PSNT is below 20 parts per million, about 12.3 lbs of nitrogen per acre is needed for every one part per million shortfall to reach the critical level.

PSNT is especially useful when wet conditions compromise pre-plant nitrogen applications or when a substantial amount of residual nitrogen is suspected, offering a timely check on nitrogen availability, according to the report.

“Nitrogen decisions are always a moving target, especially when spring weather doesn’t cooperate,” said Emerson Souza, lead author of the study and researcher at the University of Minnesota. “The PSNT gives farmers a way to read the field’s nitrogen status in real time, rather than guessing, and allows us to adjust quickly when the soil is coming up short.”

More on the story.