Given the high spatial variability of soil nitrate in fields with banded fertilizer, we suggest the following as an alternative method for soil sampling and making any desired adjustments to the Virtual PSNT in Adapt-N.
- Follow the sampling practices outlined in the Recommended Sampling Methodology, but sample away from the fertilizer bands, typically midway between the rows, to avoid fertilizer hot spots.
- Adapt-N’s Virtual PSNT accounts for fertilizer additions with applications dates that have already occurred, so the best way to compare the field measured (between-row) PSNT and the Virtual PSNT is to temporarily remove the fertilizer application from the field configuration. In most cases, you can change the rate to 1 lb and avoid having to re-enter all of the information for that application later.
- If you decide to use the lab’s PSNT numbers as the basis for Observations in Adapt-N, these should be based on the difference between the measured between-row values and the Virtual PSNT without the addition of fertilizer.
- 60 lbs of N was applied in the row pre-emergence. The Adapt-N Virtual PSNT including this application is 22 ppm.
- The between-row field-measured PSNT (sampled away from band) is 9 ppm.
- After removing the 60 lb fertilizer application from Adapt-N and re-running the recommendation on the sample date, Virtual PSNT is 13 ppm, 4 ppm higher than the field-measured PSNT.
- Add an Observation to reduce the Virtual PSNT by 4 ppm to 18 ppm.
- Remember to restore the actual fertilizer application in the Adapt-N field.