By Blake Jackson
The corn stalk nitrate test (CSNT) is a valuable end-of-season tool for assessing nitrogen (N) management in corn fields that have been in corn for two or more years according to the Cornell Field Crops newsletter. It helps identify cases where nitrogen applied during the growing season exceeded the crop’s requirements.
The Cornell research indicates that when CSNT results are above 2,000 ppm, the crop had more N than needed. While results can fluctuate yearly, fields testing over 3,000 ppm for two or more consecutive years often indicate opportunities to adjust N management without affecting yields.
In 2025, 37% of tested fields had CSNT values above 2,000 ppm, with 28% exceeding 3,000 ppm and 15% surpassing 5,000 ppm. Conversely, 34% of samples were classified as low in N.
Excessive CSNT results are closely linked to May-June precipitation patterns, with droughts during these months typically increasing the percentage of fields testing high.
Although 2025 had above-average rainfall in May and June, subsequent drought conditions in many regions reduced yields and contributed to higher CSNT levels compared to a more balanced year like 2024.
Factors such as soil type, crop and manure management history, and seasonal stresses like drought, excessive rain, weed pressure, or disease should be considered when interpreting results and planning future N management.
Due to within-field variability, accurate CSNT assessment requires dense sampling, generally at least one stalk per acre, or targeted sampling based on yield zones, soil types, or field elevations. Since 2018, adaptive nutrient management guidelines have included targeted CSNT sampling, which provides more meaningful data while reducing labor.
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Categories: New York, Crops, Corn