At-Field and On-Demand Nitrogenous Fertilizer Synthesis

Small-scale fertilizer synthesis enabled by atmospheric-pressure processes such as plasma and electrochemical technologies may be promising to mitigate the environmental and social costs associated with the energy-and carbon-intensive Haber-Bosch (HB) process. Modular nitrogen fixation systems that utilize sustainable inputs have been developed, but gaps remain regarding how these devices may integrate into agricultural practices. In this perspective, we propose a combination of nonthermal plasma-electrolytic nitrogen fixation with electrochemical soil sensors to produce fertilizer-enriched irrigation water on demand. First, we discuss the plasma technologies that could be used in an at-field responsive plasma-activated (ARPA) process. Based on current bench-scale systems, we found that ARPA synthesis could provide sufficient amounts of fixed nitrogen to meet crop demand. Next, we describe electrochemical sensor technologies for monitoring soil nitrogen and consider the barriers to implementing these technologies in fields. Further, we conducted an abbreviated life cycle analysis of the proposed ARPA concept and found potential environmental impact reductions by avoiding HB fertilizer synthesis, storage, and transportation and by reducing reactive nitrogen losses typically associated with largescale overfertilization. Finally, we consider the environmental, social, and economic implications of ARPA technologies for water treatment, fertilizer market impacts, fertilizer accessibility, safety, stakeholder buy-in, and agricultural management.