By Blake Jackson
Once on-farm research trials are established, one of the most important stages of data collection begins before side-dress nitrogen applications.
Many projects supported through the Nitrogen Optimization Pilot Program (NOPP) rely on soil sampling during this period to better understand nitrogen availability and crop needs.
In corn fields, soil samples are commonly collected in June when plants reach about 12 inches in height and before side-dress nitrogen is applied.
Researchers use the Pre-Sidedress Nitrate Test (PSNT) to measure the amount of nitrate present in the top foot of soil.
The results can help determine whether additional nitrogen fertilizer is needed and provide valuable information for evaluating crop performance later in the season.
While PSNT traditionally measures nitrate levels, current NOPP projects are also analyzing ammonium concentrations.
Researchers hope that assessing both forms of nitrogen will provide a more complete understanding of a field’s nutrient status and improve recommendations for nitrogen management.
The collected data also supports broader efforts to examine soil health indicators and determine whether they can help predict optimal in-season nitrogen rates.
This work was conducted in 2025 and expanded in 2026, with more than 80 Wisconsin fields participating in the sampling effort.
Researchers are now compiling and analyzing the information gathered from these trials. Additional NOPP funding opportunities are expected in 2027, with new application details anticipated later this year.
Photo Credit: gettyimages-kotenko-a
Categories: Wisconsin, Crops, Corn, Sustainable Agriculture