By Emerson Souza and Fabian Fernandez
If you're using the Pre-Sidedress Nitrate Test (PSNT) to guide your nitrogen (N) decisions in corn, here’s the good news: We’ve updated the critical number you should aim for, based on field trials conducted across the major corn production regions of Minnesota.
Even more important, PSNT becomes especially valuable when weather disrupts your normal N management. If wet soils prevented a pre-plant N application, or if you applied early but then experienced heavy rainfall, PSNT offers a timely, in-season check on how much nitrate remains in the root zone, and whether a sidedress application might pay off.
Based on 34 field experiments, we found that a PSNT value of 20 ppm of nitrate-N in the top 12 inches of soil at the V4-V6 stage reliably delivers 97% of maximum corn yield. That’s your target.
Source : umn.edu