Evaluation of forage grass response to nitrogen application rate in a controlled greenhouse study

Authors: Duff, Alison; Panke-Buisse, Kevin; Bleier, Jonathan; Brink, Geoffrey

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/6/2026
Publication Date: 1/31/2026
Citation: Duff, A., Panke-Buisse, K., Bleier, J.S., Brink, G.E. 2026. Evaluation of forage grass response to nitrogen application rate in a controlled greenhouse study. Agrosystems, Geosciences & Environment. https://doi.org/10.1002/agg2.70308.
DOI: https://doi.org/10.1002/agg2.70308

Interpretive Summary: Productive, high-quality pasture is essential to profitable grazing operations. Application of nitrogen (N) fertilizer directly impacts pasture growth, but producers must be careful to only apply N that can be taken up by pasture plants, rather than lost to the environment. We evaluated three grasses (meadow fescue, orchardgrass, and tall fescue) for their growth and ability to take up applied N and compared their performance in soil types and across six nitrogen application rates (0, 67, 135, 202, 269, and 336 kg N/ha). For all species, grass productivity increased with N rate up to 202 kg N/ha, and orchardgrass had the highest forage accumulation at all N rates. The efficiency of all species in taking up and utilizing N declined with increasing N rates. In pasture systems with these species in the warm continental climates, N fertilizer timing and application strategy should be determined based on weather, pasture conditions, and livestock demand.

Technical Abstract: Productive forage with sufficient nutritive value is essential to profitable grazing operations. Application of nitrogen (N) fertilizer directly impacts pasture growth, but N rates must be carefully calibrated to minimize production costs and losses to the environment. We evaluated forage accumulation response, nitrogen use efficiency (NUE), and % 15N recovery of meadow fescue [Schedonorus pratensis (Huds.) P. Beauv.], orchardgrass (Dactylis glomerata L.), and endophyte-free tall fescue [Schedonorus phoenix (Scop.) Holub] in response to N rate in a controlled greenhouse environment using two soil types. Nitrogen was split-applied at cumulative annual rates of 0, 67, 135, 202, 269, and 336 kg N/ha. The first N application was 15N-enriched 5% atom ammonium nitrate (NH4NO3) solution, while the three subsequent N applications were made following harvest events with reagent-grade NH4NO3. Nitrogen recovery from the first application was estimated from the atom % 15N in the dry matter (DM) sample from each harvest event. For all species, DM forage accumulation increased with N rate up to 202 kg N/ha, and orchardgrass had the greatest DM accumulation at all N rates. NUE in all species declined with increased N. % 15N recovery of the first fertilizer application was significantly different across species and N rates, ranging from 35% to 70%. In pasture systems with these species in warm summer continental climates, N fertilizer timing and application strategy should be calibrated with weather, pasture conditions, and livestock demand.