Precipitation influences pre-sidedress soil nitrate thresholds for corn production

Authors: SOUZA, EMERSON - University Of Minnesota; FERNÁNDEZ, FABIÁN - University Of Minnesota; FABRIZZI, KARINA - University Of Minnesota; COULTER, JEFFREY - University Of Minnesota; Venterea, Rodney; KAISER, DANIEL - University Of Minnesota; ROSEN, CARL - University Of Minnesota; VETSCH, JEFFREY - University Of Minnesota; PAGLIARI, PAULO - University Of Minnesota; WILSON, MELISSA - University Of Minnesota; MIAO, YUXIN - University Of Minnesota; MIZUTA, KATSUTOSHI - University Of Minnesota; NEGRINI, RENZO - University Of Minnesota; KJAERSGAARD, JEPPE - Minnesota Department Of Agriculture; BERNAU, DAWN - Minnesota Department Of Agriculture; SHARMA, VASUDHA - University Of Minnesota

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/18/2025
Publication Date: 6/5/2025
Citation: Souza, E., Fernández, F.G., Fabrizzi, K.P., Coulter, J.A., Venterea, R.T., Kaiser, D.E., Rosen, C.J., Vetsch, J.A., Pagliari, P.H., Wilson, M., Miao, Y., Mizuta, K., Negrini, R., Kjaersgaard, J., Bernau, D., Sharma, V. 2025. Precipitation influences pre-sidedress soil nitrate thresholds for corn production. Journal of Environmental Quality. 89(3). Article e70085. https://doi.org/10.1002/saj2.70085.
DOI: https://doi.org/10.1002/saj2.70085

Interpretive Summary: Minnesota is one of the most important corn-producing states in the US and applies large inputs of nitrogen fertilizer to optimize production. This study assessed the usefulness of soil nitrogen concentration measurements taken at the V4 to V6 stage of plant development to determine the need for additional in-season fertilizer applications. The study included data from 34 field experiments conducted from 2012-2019 within the main corn-producing regions of Minnesota. Based on these studies, a soil nitrate concentration of 20 mg N per kg soil was determined to be the critical level required to achieve 97% of maximum corn grain yield. To increase soil nitrate concentrations up to the critical level, it was determined that an additional application of 13.8 kg N per ha of nitrogen fertilizer is needed per every 1 mg N per kg soil increase in soil nitrate concentration. Model estimates of the critical soil nitrate level were not improved by considering site soil characteristics, location, or previous crop. These results can be used by land managers to improve the efficiency of nitrogen fertilizer used for corn production, and thereby reduce input costs as well as negative environmental impacts associated with nitrogen fertilizers.

Technical Abstract: Minnesota is one of the most important corn (Zea mays) producing states in the US and requires large inputs of nitrogen for optimal production. In-season critical soil nitrate (NO3--N) concentration threshold as a reference value to adjust fertilization rates could be a measurement used to improve nitrogen (N) management and reduce environmental impacts. Corn grain yield response to in-season (i.e., V4-V6 corn growth stages) soil NO3--N concentration was assessed to determine a critical pre-sidedress soil NO3--N concentration (PSNT) to achieve the greatest percentage of maximum corn grain yield under Minnesota conditions. The study included data from 34 field experiments conducted from 2012-2019 within the main corn production regions of Minnesota. Relationships between PSNT and relative corn grain yield were analyzed using the quadratic-plateau regression model. A PSNT of 20 ± 2.5 mg NO3--N kg-1 of soil was the critical level to reach 97% of maximum corn grain yield. To increase PSNT concentrations up to the critical threshold, 13.8±2.4 kg N ha-1 rate are needed to increase soil NO3--N concentration by 1 mg kg-1. However, since our model was based on pre/at planting N application, the performance of this rate in increasing soil NO3--N concentrations should be further assessed as a sidedressing practice to validate our results. Based on this analysis, the reported PSNT critical level is applicable across the state as limited improvements were achieved when considering soil characteristics, location, and previous crop.