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1. Soil nitrogen fertilization reduces relative leaf nitrogen allocation to photosynthesis

   https://doi.org/10.1093/jxb/erad195  

   Waring, Elizabeth F; Perkowski, Evan A; Smith, Nicholas G (May 2023, Journal of Experimental Botany)

   Rogers, Alistair (Ed.)

   Abstract The connection between soil nitrogen availability, leaf nitrogen, and photosynthetic capacity is not perfectly understood. Because these three components tend to be positively related over large spatial scales, some posit that soil nitrogen positively drives leaf nitrogen, which positively drives photosynthetic capacity. Alternatively, others posit that photosynthetic capacity is primarily driven by above-ground conditions. Here, we examined the physiological responses of a non-nitrogen-fixing plant (Gossypium hirsutum) and a nitrogen-fixing plant (Glycine max) in a fully factorial combination of light by soil nitrogen availability to help reconcile these competing hypotheses. Soil nitrogen stimulated leaf nitrogen in both species, but the relative proportion of leaf nitrogen used for photosynthetic processes was reduced under elevated soil nitrogen in all light availability treatments due to greater increases in leaf nitrogen content than chlorophyll and leaf biochemical process rates. Leaf nitrogen content and biochemical process rates in G. hirsutum were more responsive to changes in soil nitrogen than those in G. max, probably due to strong G. max investments in root nodulation under low soil nitrogen. Nonetheless, whole-plant growth was significantly enhanced by increased soil nitrogen in both species. Light availability consistently increased relative leaf nitrogen allocation to leaf photosynthesis and whole-plant growth, a pattern that was similar between species. These results suggest that the leaf nitrogen–photosynthesis relationship varies under different soil nitrogen levels and that these species preferentially allocated more nitrogen to plant growth and non-photosynthetic leaf processes, rather than photosynthesis, as soil nitrogen increased. 

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2. Targeting Nitrogen Metabolism and Transport Processes to Improve Plant Nitrogen Use Efficiency

   https://doi.org/10.3389/fpls.2020.628366  

   The, Samantha Vivia; Snyder, Rachel; Tegeder, Mechthild (March 2021, Frontiers in Plant Science)

   null (Ed.)

   In agricultural cropping systems, relatively large amounts of nitrogen (N) are applied for plant growth and development, and to achieve high yields. However, with increasing N application, plant N use efficiency generally decreases, which results in losses of N into the environment and subsequently detrimental consequences for both ecosystems and human health. A strategy for reducing N input and environmental losses while maintaining or increasing plant performance is the development of crops that effectively obtain, distribute, and utilize the available N. Generally, N is acquired from the soil in the inorganic forms of nitrate or ammonium and assimilated in roots or leaves as amino acids. The amino acids may be used within the source organs, but they are also the principal N compounds transported from source to sink in support of metabolism and growth. N uptake, synthesis of amino acids, and their partitioning within sources and toward sinks, as well as N utilization within sinks represent potential bottlenecks in the effective use of N for vegetative and reproductive growth. This review addresses recent discoveries in N metabolism and transport and their relevance for improving N use efficiency under high and low N conditions. 

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3. Chemical Potential of Nitrogen at High Pressure and High Temperature: Application to Nitrogen and Nitrogen-Rich Phase Diagram Calculations

   https://doi.org/10.1021/acs.jpcc.9b00476  

   Alkhaldi, Hanof; Kroll, Peter (February 2019, The Journal of Physical Chemistry C)
4. Metabasic rocks as important nitrogen carriers to forearc depths: Implications for deep nitrogen cycling

   https://doi.org/10.1016/j.gca.2023.10.007  

   Mallik, Ananya; Rebaza, Anna M.; Kapp, Paul; Li, Long; Du, Yifan; Al Shams, Ahmed; Cooperdock, Emily H.G. (November 2023, Geochimica et Cosmochimica Acta)
5. Nitrogen cycling in tropical Atlantic Forest differing in exposure to urban atmospheric nitrogen deposition

   https://doi.org/10.1007/s11104-017-3421-8  

   Ponette-González, A. G.; Perroni, Y.; Weathers, K. C.; de Souza, P. A.; García-Oliva, F.; de Mello, W. Z. (September 2017, Plant and Soil)