Kendra Rose, Agriculture and Natural Resources Educator, Crawford County and Jason Hartschuh, Extension Field Specialist, Dairy Management and Precision Livestock, The Ohio State University
Nitrogen fertilization of cereal grains for forage is important for both yield and quality. Using an application method split between the spring and fall is important and can increase yield and tillering, can help spread the risk of nitrogen loss, and improve the nitrogen use efficiency. Knowing what your target yield is will help you determine how much the split application will be.
When fertilizing in the spring, it’s important to have the correct timing and apply the nitrogen as the crop breaks dormancy. This allows there to be less of a chance for runoff and leaching and the ground is not frozen, allowing the nitrogen to move into the soil to be utilized by the crop. Dormancy will break at different times in the spring depending upon the species grown. Cereal rye and triticale will green up first, while wheat and barley will be much slower. Nitrogen applied in the fall or split between the fall and spring will result in more constant forage production throughout the season compared to one spring application, though, spring applied nitrogen was found to increase yields up to 200 lb/ac compared to other methods based on work done in Oklahoma.
In recent research studies, we have found that in order to optimize yield, you need to add at least 30 lb/ac of nitrogen in the fall. To help determine a realistic yield potential, look at the yield from the past five years, take out the highest and lowest yield and average the remaining three yields (Lindsey and Lentz, 2025). This will should reflect a realistic yield potential to help determine the optimum nitrogen rate. We have found that crude protein in cereal rye was significantly increased by a 25 lb/ac increase in spring nitrogen application, regardless of the fall nitrogen rate. The dry matter yield can be increased by using the fall and spring split application method. Our studies have found that 20 lb/ac of fall nitrogen had a significant increase in cereal rye yield of at least 1 ton/ac of dry matter. The addition of 20 lb/ac or more of spring nitrogen to the current recommendation of 50 lb/ac can significantly increase the dry matter yield by 0.5 to 1 ton/ac.
The crude protein levels can also be improved through split nitrogen applications. The spring nitrogen application is the primary driver of crude protein; one of our studies showed that an application of 70 lb/ac of nitrogen has been found to increase crude protein. Though, one of our studies shows that 90 lb/ac of fall applied nitrogen can statistically increase the crude protein. Other quality factors such as total digestible nutrients (TDN) can also be affected by nitrogen fertilization. In our research, TDN in cereal rye was found to be negatively affected by higher spring nitrogen rates but was not influenced by fall nitrogen treatments. Applying nitrogen in the fall has also been seen to increase neutral detergent fiber (NDF) compared to trials where no nitrogen has been applied. This may be due to slightly more advanced growth stages at harvest when the fall nitrogen was applied compared to only spring nitrogen.
Another thing to be mindful of when applying nitrogen fertilizer is your soil type. Sandier soil may require higher nitrogen rates compared to loamy or clayey soil due to lower water holding capacity and organic matter levels. Drainage within your field is also important; soils that are waterlogged in the spring during critical periods of growth and development can reduce the yield and maturity, and there could be a significant portion of applied N lost due to denitrification
To help make management decisions, a few tools can be used to measure canopy cover. Two examples of tools to use are Normalized Difference Vegetation Index (NDVI; White, 2023) and Canopeo (Patrignani and Ochsner, 2015). NDVI is a sensor that is used in a non-destructive way to estimate the biomass’s nitrogen content. In our studies and others, NDVI has been found to be equal or superior to other indices in predicting percent ground cover. Canopeo is an automatic color threshold image analysis tool to determine ground coverage. One known limitation of Canopeo is the need to keep the camera an adequate height above the canopy. A forage analysis should also be used to determine the nutritional value of the forage for livestock performance. Utilizing the crude protein content of your forage test and knowing your yield per acre allows you to calculate if you removed all the nitrogen you applied to your soil for the forage production. Knowing the nutritional levels of a feed will help you make better decisions of what to feed and if you need any additional ration supplements.
References
Altom, W., Rogers, J. L., Raun, W. R., Johnson, G. V., and Taylor, S. L. 1996. Long-term rye-wheat-ryegrass forage yields as affected by rate and date of applied nitrogen. Journal of Production Agriculture, 9(4), 510–516. https://doi.org/10.2134/jpa1996.0510
Culman, S., Fulford, A., Camberato, J., and Steinke, K. 2020. Tri-State Fertilizer Recommendations. Bulletin 974. College of Food, Agricultural, and Environmental Sciences, Columbus, OH, The Ohio State University.
Lindsey, L., and Lentz, E. 2025. Spring Nitrogen Recommendations for Winter Wheat. Agronomic Crops Network, March issue. https://agcrops.osu.edu/newsletter/corn-newsletter/2025-06/spring-nitrogen-recommendations-winter-wheat
Patrignani, A., and Ochsner, T. E. 2015. Canopeo: A powerful new tool for measuring fractional green canopy cover. Agronomy Journal, 107(6), 2312–2320. https://doi.org/10.2134/agronj15.0150
Prabhakara, K., Hively, W. D., and McCarty, G. W. 2015. Evaluating the relationship between biomass, percent groundcover and remote sensing indices across six winter cover crop fields in Maryland, United States. International Journal of Applied Earth Observation and Geoinformation, 39, 1–15. https://doi.org/10.1016/j.jag.2015.03.002
White, C. 2023. Using an NDVI sensor to estimate cover crop nitrogen content. Penn State Extension, May 28 issue. https://extension.psu.edu/using-an-ndvi-sensor-to-estimate-cover-crop-nitrogen-content