Stalk Nitrate Test Results for New York Corn Fields from 2010 through 2025

Sanjay Gami1, Juan Carlos Ramos Tanchez1, Mike Reuter2, and Quirine M. Ketterings1

Cornell University Nutrient Management Spear Program1, and Dairy One2

Introduction

              The corn stalk nitrate test (CSNT) is an end-of-season evaluation tool for N management for 2nd or higher year corn fields. It allows for identification of situations where N during the growing season exceeded crop needs. Research shows that the crop had more N than needed when CSNT results exceed 2000 ppm. Results can vary across years, but where CSNT values exceed 3000 ppm for two or more years, it is highly likely that N management changes can be made without impacting yield. 

Findings 2010-2025

              In 2025, 37% of all tested fields had CSNT-N greater than 2000 ppm, while 28% were over 3000 ppm and 15% exceeded 5000 ppm (Table 1). In contrast, 34% of the 2025 samples were low in CSNT-N. Over the years, the percentage of samples testing excessively in CSNT-N was most correlated with the total precipitation in May-June with droughts in those months translating to a greater percentage of fields testing excessive. The year 2025 was classified as wet based on May-June rainfall but many areas experienced severe drought conditions after a wet spring, lowering yields and contributing to a higher percentage of stalks testing excessive in CSNT in 2025 compared to a more ideal rainfall year like 2024. Because crop and manure management history, soil type and growing conditions all impact CSNT results, conclusions about future N management should consider the events of the growing season. This includes weed and disease pressure, lack of moisture in the root zone in drought years, lack of oxygen in the root zone due to excessive rain in wet years, and any other stress factor that impact crop growth and N status.

Note: Data prior to 2013 reflect stalk submissions to NMSP; 2013, 2014, and 2017-2025 data include results from NMSP and Dairy One; 2015-2016 has samples from NMSP, Dairy One, and CNAL. Yield data source: USDA – National Agricultural Statistics Service. Rainfall data source: CLIMOD2, Northeast Regional Climate Center. Total number of samples: 12188. The year 2025 was an exceptionally bad year with a wet spring delaying planting followed by a drought.

              Within-field spatial variability can be considerable, requiring (1) high density sampling (equivalent of 1 stalk per acre at a minimum) for accurate assessment of whole fields, or (2) targeted sampling based on yield zones, elevations, or soil management units. The 2018 expansion of adaptive management options for nutrient management now includes targeted CSNT sampling because of findings that targeted sampling generates more meaningful information while reducing the time and labor investment into sampling. Two years of CSNT data are recommended before making any management changes unless CSNT’s exceed 5000 ppm, in which case one year of data is sufficient.

Figure 1: In drought years more samples test excessive in CSNT-N. The last 16 years included six drought years (2012, 2016, 2018, and 2020 through 2023), four wet springs (2011, 2013, 2017, and 2025, which was wet followed by a severe drought), and five years labelled normal (2010, 2014, 2015, 2019, and 2024) determined by May-June rainfall (less than 7.5 inches in drought years, 10 or more inches in wet years). Weather data are state averages; local conditions may have varied from state averages.

Relevant References

Acknowledgments

              We thank the farmers and farm consultants that sampled their fields for CSNT over the years. For questions about these results contact Quirine M. Ketterings at 607-255-3061 or qmk2@cornell.edu, and/or visit the Cornell Nutrient Management Spear Program website at: http://nmsp.cals.cornell.edu/. 





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