High N availability decreases N uptake and yield under limited water availability in maize

Authors: FLYNN, NORA - Colorado State University; Comas, Louise; Stewart, Catherine; FONTE, STEVEN - Colorado State University

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/2023
Publication Date: 8/31/2023
Citation: Flynn, N.E., Comas, L.H., Stewart, C.E., Fonte, S.J. 2023. High N availability decreases N uptake and yield under limited water availability in maize. Scientific Reports. 13. Article e14269. https://doi.org/10.1038/s41598-023-40459-0.
DOI: https://doi.org/10.1038/s41598-023-40459-0

Interpretive Summary: Water and nitrogen are the most limiting factors to plant productivity globally, but we lack a critical understanding of how water availability impacts plant N needs and N losses from the environment. We investigated impacts of N application and water availability on plant and N metrics within a semi-arid system in northeastern Colorado, USA. High N availability reduced grain yield and shoot growth under both limited and full water availability. Under low N availability, plant N concentrations in aboveground tissues showed greater recovery of N than what was applied in the low N treatments under both full and limited water availability. This enhanced recovery underscores the need to better understand both plant soil foraging and processes governing resource availability under these conditions. Limited water availability during vegetative growth reduced both grain yield and crop water use, and thus, did not improve water productivity. Finally, limited water availability reduced N uptake across all N treatments and left 30% more soil NO3 deep in the soil profile at the end of the season than under full water availability. Our results show that plant N use is not linearly related to water use and emphasize the need for an integrated understanding of water and N interactions, plant foraging for these resources, and the dynamics of processes that make N available to plants.

Technical Abstract: Water and nitrogen (N) are the most limiting factors to plant productivity globally, but we lack a critical understanding of how water availability impacts N requirements of plants and losses from the environment. Plant N requirements are particularly uncertain when water is limited because of the interactive effect of water and N on plant growth, plant N demand, and plant N uptake. We investigated impacts of N application and water availability on plant and N metrics, including above and belowground growth, water productivity, N productivity, N uptake, N recovery, and greenhouse gas emissions within a semi-arid system in northeastern Colorado, USA. High soil N availability depressed grain yield and shoot growth under limited water availability, with similar trends also under full water availability, despite no indication of physical toxicity. Under low N availability, plant N concentrations in aboveground tissues showed greater recovery of N than what was applied in the low N treatments under both full and limited water availability. This enhanced recovery underscores the need to better understand both plant soil foraging and processes governing resource availability under these conditions. Limited water availability during vegetative growth reduced both grain yield and crop water use, and, thus, did not improve water productivity. Finally, limited water availability reduced N uptake across all N treatments and left 30% more soil N-NO3- deep in the soil profile at the end of the season than under full water availability. Our results show that plant N use is not linearly related to water use and emphasize the need for an integrated understanding of water and N interactions, plant foraging for these resources, and the dynamics of processes that make N available to plants.