Corn Stalk Nitrate Test (CSNT)

Corn Stalk Nitrate Test (CSNT) is performed by farmers to evaluate the N levels within corn just before harvest time or immediately afterwards. The CSNT provides an analysis of N management practices, and whether they were adequate or excessive during the growing season. These results give an evaluation of N management practices for a specific field. Running CSNT will require multiple years of testing to accumulate an accurate representation of N practices.

A CSNT should be performed either a week before corn harvest or within four days immediately following harvest time. It is recommended that CSNT be performed on 2nd or higher year corn. The CSNT can help gauge effectiveness of new N protection programs or the application of N on fields.

CSNT Sampling Guidelines

  1. Sampling area should be in a field < 15 acres in size.
  2. Take samples from 15 different areas in field to provide a look at management and soil type impact.
  3. Collecting samples will require use of tape measure, side cutters or plant pruners.
  4. A Pre-Harvest sample should be taken from 6-14 inches from the ground and sample segment should be 8 inches long.
  5. A Post-Harvest sample should be taken from 2-8 inches from the ground and sample segment should be 6 inches long.
  6. Quarter samples into 4 pieces and submit one quarter for testing purposes. There should be a total of 15 quarters collected.
  7. Do not allow sample segment to become contaminated with soil, as it may impact proper test results.
  8. Samples should be placed in a paper bag to allow some drying but prevent the growth of mold. Do not freeze sample. Ship samples to lab within 24 hours.

Please include a completed copy of CSNT Sample Submission Form when submitting samples.

CSNT Interpretation

CSNT ppm N N available to corn plant N Guidelines
<250 Low Not enough N available.
2250-750 Marginal Continue CSNT testing for further evaluation.
750-2,000 Optimal There is enough N present to support corn plant.
>2,000 Excess Corn plant had access to excessive amounts of N. If field applied with manure and/or N fertilizer, this may be cause.

Work with your agronomy consultant or other certified crop professional after receiving results to establish a N program for your corn fields.