Corn grain yield response to nitrogen rate timing, source, and nitrification inhibitor in Missouri

Authors: SINGH, GURBIR - University Of Missouri; NELSON, KELLEY - University Of Missouri; KAUR, GURPREET - University Of Missouri; PAL, PANKAJ - University Of Missouri; CARSON, ROBERS - University Of Missouri; LORY, JOHN - University Of Missouri; DAVIS, MORGAN - University Of Missouri; CHLAPECKA, JUSTIN - University Of Missouri; Abendroth, Lori; Ransom, Curtis; CALHOUN, JUSTIN - University Of Missouri; BRADLEY, WILSON - University Of Missouri; NAUMANN, H - University Of Missouri

Submitted to: North Central Extension Industry Soil Fertility Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/20/2024
Publication Date: 11/20/2024
Citation: Singh, G., Nelson, K., Kaur, G., Pal, P., Carson, R., Lory, J., Davis, M., Chlapecka, J., Abendroth, L.J., Ransom, C.J., Calhoun, J., Bradley, W., Naumann, H. 2024. Corn grain yield response to nitrogen rate timing, source, and nitrification inhibitor in Missouri. Proceedings of 54th North Central Soil Fertility Conference, November 20-21, 2024, Des Moines, Iowa.

Interpretive Summary: Farmers need to apply the right amount of nitrogen fertilizer to grow profitable crops and protect the environment. However, determining the correct amount can be challenging due to various factors like weather, soil conditions, crop rotation, and fertilizer management methods. In Missouri, farmers currently use a formula from the 1980s to decide corn nitrogen fertilizer requirements. This method does not consider newer farming practices or differences in growing conditions. To address these gaps, researchers have started a project funded by the Missouri Fertilizer Control Board in 2023. The project aims to update guidelines by testing new practices and tools, such as biological products, cover crops, and soil health indicators. The goal is to provide farmers with more accurate recommendations considering new technologies and field variations, resulting in better crop growth and reduced environmental impact. The latest findings from 2023 and 2024 will be shared at the conference.

Technical Abstract: Nitrogen response depends on several factors including weather conditions, soil N supply capacity, previous crop in rotation, plant population, and fertilizer management practices. Fertilizer management practices include fertilizer rate, source, application timing, placement, and use of nitrogen stabilizer. In Missouri, the nitrogen fertilizer rate recommendations for corn are based on the yield goal equation. This equation includes the target plant population, pounds of nitrogen removed per thousand plants, and a product of yield goal with pounds of nitrogen per yield unit. This equation has a soil health adjustment factor that is based on the organic matter content of the soil. The organic matter adjustment factor is based on soil texture and cation exchange capacity and provides a soil N credit in pounds of nitrogen per acre. The parameters used in the yield goal equation were updated in the 1980’s. The yield goal equation does not integrate new practices such as cover crops, bio-stimulants, and nitrogen stabilizers. Moreover, the nitrogen recommendations do not incorporate variations in nitrogen supply across the landscape for different productivity zones. Therefore, a multi-site project funded by the Missouri Fertilizer Control Board began in 2023 to address these gaps, add new practices, and help update nitrogen fertilizer recommendations for Missouri. The specific objectives are to evaluate biological input products; cover crops; nitrification inhibitors and other biological management technologies for improving nitrogen use efficiencies; evaluate soil health indicators as yield predictors; evaluate the effect of landscape position and soil conditions on productivity and soil nitrogen supply; calibrate the integration of soil health measurements into fertilizer nitrogen recommendations and improve calibrations of in-season nitrogen prediction tools. Updated results from 2023 and 2024 will be presented at the conference.