Towards Sustainable Nitrogen Use Connecting Human Society and Nature

Progress and Results (2022 Year)

Research purpose and content

1. Executive summary

1)  Objectives and background

Sustai-N-able (SusN) Project targets the nitrogen (N) issue that is a tradeoff between the benefits of nitrogen (N) use as fertilizers, industrial materials, and energy sources and the threats of N pollution from local to global scales (Fig. 1). The purposes of SusN are to create a universal and globally applicable methods for assessing the N issue, future scenarios, and inter- and trans-disciplinary knowledge on the N issue, in cooperation with international activities while focusing mainly on Japan, and to solve the N issue in 2050 with food equity and good health of humanity and nature supporting the international N management initiated by the United Nations Environment Programme (UNEP). In the limited research period until FR5, the following three breakthroughs will be achieved: (1) developing a framework to visualize the benefits of N use and the threats of N pollution based on scientific knowledge of the driver–pressure–state–impact–response (DPSIR) of the N issue (N-DPSIR), (2) promoting recognition of the N issue still not well known among various stakeholders (N recognition), and (3) designing sustainable N use in the future (future N planning).

Fig. 1. Nitrogen issue is a tradeoff between nitrogen use (benefits) and nitrogen pollution (threats)

N pollution causes various impacts such as climate change, stratospheric ozone depletion, air pollution, water pollution, eutrophication, and acidification. The annual damage cost due to N pollution in 2000s in the world was estimated to be 340–3400 billion USD (UNEP 2019). The amount of anthropogenic creation of reactive N (Nr, N compounds other than inert and harmless dinitrogen [N₂]) now exceeds the natural creation (Fowler et al. 2013). However, the N use efficiency (NUE) of human activities is low, ca. 20% in the world (Sutton et al. 2013). A large amount of N waste is generated eventually, part of which lost to the environment as Nr induces the N pollution. The global N cycling has already transgressed the planetary boundary (Rockstörm et al. 2009, Steffen et al. 2015).

The world mean NUE of crop production is ca. 50% and that of livestock production ranges from 5% to 20% (Lassaletta et al. 2014, Bouwman et al. 2013). Preference for animal products, therefore, lowers the food system NUE, and food loss wastes all the N input to produce the lost food. Economic disparity of fertilizer availability results in regions with too much and too little N in the world. Places of production and consumption often cross borders, causing that consuming countries eventually contribute to the N pollution in producing countries. Global N waste has been increasing since 1961, approximately four times in 2005 and will be six times in 2050 compared to that in 1961 (Sutton et al. 2021). Agricultural N input in 2050 will increase to support future food demand that intensifies the surplus N in croplands (Mogollón et al. 2018). A new N use as fuel ammonia (NH₃) is being created (Nishina, 2022). In addition to watching future progress, our N use should be shifted more sustainable one to mitigate the threats of N pollution.

N waste in Japan from 2000 to 2015 was ca. 6 Tg N yr^–1, and its per capita value was approximately double of the world mean (Hayashi et al. 2021a). More than 80% of the N waste in Japan originated from the imported commodities. Therefore, limited opportunities are available for N recycle within the nation, and the exporting countries suffer N pollution during the production of exports. N flow analysis of fish products is also important in Japan because those account for ca. 20% of the food N supply. Although the NUE of fish products can be hundreds of percent owing to natural catch, the sustainability of fishery resources is essentially important. The Nr lost to the environment has showed a decreasing trend in Japan, where the decrease in nitrogen oxides (NO_X) from transportation sector was remarkable. Meanwhile, Japan focuses on NH₃ fuel in the momentum of decarbonization because combusted NH₃ does not create carbon dioxide. The Ministry of Economy, Trade and Industry (METI) announced a plan in September 2021 that 25 Tg N yr^–1 of NH₃, corresponding to 18% of the world NH₃ production in 2015, will be supplied for fuels in 2050 (METI, 2021). NH₃ supply for Japan will rely on import due to cost efficiency. There are concerns of economic competition among N uses and N pollution due to NO_X emissions from combusted NH₃ and leakage of NH₃ to the environment. The future N use in Japan is uncertain and its change will spread to the world via international trade. It is expected that policy, technology, and behavior changes for sustainable N use in Japan will contribute to solving the world’s N issue.

The International Nitrogen Initiative (INI), officially launched in 2003, is an expert group to tackle the N issue. INI plans international projects, supports international organizations, and hosts the International Nitrogen Conference (INI Conference) on a regular basis every three years so far except the last one affected by COVID-19 (INI, 2022). SusN Project Leader (hereinafter PL) has served as the director of the INI East Asia Regional Centre from November 2022. SusN will cooperate with INI closely. UNEP is implementing the International Nitrogen Management System (INMS) Project, planned by INI, to apply scientific knowledge to international policy (October 2017–June 2023; INMS, 2022a). PL and some SusN members have contributed to INMS as co-leads and members. In conjunction with the United Nations Sustainable Development Goals, INMS has set a goal of halving the N waste and will publish the International Nitrogen Assessment (INA) in June 2023. PL is one of the INA editors, and some SusN members are authors of INA. It is recognized that SusN is a spinoff of INMS (INMS, 2022b). The “Resolution on Sustainable Nitrogen Management” was adopted twice at the 4th and 5th United Nations Environment Assembly (UNEA). 6th UNEA (UNEA-6) is scheduled for February 26 to March 1, 2024, and it is expected that international consensus on sustainable N management will be accelerated. UNEP established a Nitrogen Working Group (NWG) to build consensus among participating countries. Japan, which has not yet to participate NWG, is also required to set its national focal point. SusN anticipates supporting discussions on sustainable N use in Japan in collaboration with various stakeholders.

N research has progressed in individual fields, e.g., natural N processes, environmental monitoring, industrial N uses, N footprint, and agro-environmental policies, etc. However, further research is needed to address the N issue, e.g., responses of natural ecosystems to changes in N flow, N flow in human society and its future changes, effects of policy, technology, and behavior changes on the N issue, and a framework to support decision making by visualizing the N-DPSIR. Transdisciplinary research with various stakeholders to design sustainable N use is essential because N is deeply linked to all human activities through food, goods, and energy. It is expected that the Future Design (FD), attracting attention as a method to co-create ideas to solve issues from the perspective of future generations, is useful for creating ideas to realize sustainable N use. SusN is collaborating with the RIHN Strategic Program FD Project (FR, PL: Nakagawa) to apply FD with supports of Advisor Saijo, the former director of the 3rd phase Program 3.

2) How does the research contribute to the solution of the global environmental problems? 

SusN aims to deepen research in each field on the N issue and to make the following three breakthroughs: (1) N-DPSIR, (2) N recognition, and (3) future N planning. N-DPSIR will provide a tool for evaluating and visualizing changes in N use and N pollution due to changes in policy, technology, and behavior. N recognition will compile the latest interdisciplinary knowledge (e.g., Japanese Nitrogen Assessment [JNA], review of RIHN CRs on their N aspects [RIHN CRs N Review], various specialized books), transdisciplinary knowledge (e.g., questionnaire of N and environmental issues, project leaflet with key facts of the N issue, narratives as movies and reading materials), and approach to various stakeholders using the created questionnaires and narratives. Future N planning will practice FD with various domestic and international stakeholders (e.g., policy makers, experts, consumers, and producers, etc.) and promote collaboration with international organizations such as UNEP and INI. The difficulty in balancing the benefits and threats has hampered the resolution of the N issue. SusN will provide quantitative information on the effects of various countermeasures and behavioral changes based on the causal relationship between N use and N pollution. SusN will provide opportunities for future generations to come up with ideas for the sustainable N use. As a result, it is expected that awareness of the N issue will increase both domestically and internationally, the existing and new initiatives for sustainable N use are strengthened, and the breakthroughs in solving the N issue are achieved.

3) Methodology, structure and schedule

The N issue encompasses all human activities and the environment, and many questions remain unsolved. Therefore, the first pillar of SusN is to accumulate the latest knowledge of the N issue covering nature and human society, and to conduct interdisciplinary research at the forefront (e.g., field survey, laboratory experiments, numerical analysis, questionnaire surveys, data preparation, scenario construction, etc.). It is needed to support the policy makers and each stakeholder to address the N issue not well recognized like the case of climate change 30 years ago. A mechanism is needed to create ideas freely to permeate the awareness of N issue and realize sustainable N use for future generations, to which the three breakthroughs, (1) N-DPSIR, (2) N recognition, and (3) future N planning contribute. The second pillar is transdisciplinary research that integrates existing and new interdisciplinary knowledge and co-creates transdisciplinary knowledge with other stakeholders to achieve the three breakthroughs. The third pillar is to cooperate with domestic and international N-related programs and projects. It is expected that the collaboration with other programs and projects generates many spinoff activities from interactions between those involved, and that new projects towards sustainable N use will be inherited after the completion of SusN.

SusN has three interdisciplinary research units (RUs) to cover all aspects of the N issue that connect nature and human society: Natural Cycling Unit, e.g., provision of knowledge on the environmental N science; Human Society Unit, e.g., analysis of N flow in the production and consumption of food, goods, and energy; and Economic Evaluation Unit, e.g., quantification of social costs of human activities on the N issue such as food production and consumption. SusN also has one transdisciplinary RU, i.e., Future Planning Unit, to achieve the three breakthroughs by working with the other RUs closely. SusN sets common analysis sites, connects spatial scales from local to global, and conducts research from both bottom-up and top-down approaches (Fig. 2).

Fig. 2. Schematic view of research approach. Three interdisciplinary research units (RUs; natural cycling, human society, and economic evaluation) deepen each research, and one transdisciplinary unit (Future Planning) works to achieve the three breakthroughs, i.e., N-DPSIR analysis, N recognition, and future N challenge, in close collaboration with the other RUs. DPSIR, driver-pressure-state-impact-response; INMS, International Nitrogen Management System; UNEP, United Nations Environment Programme; and INI, International Nitrogen Initiative.

The SusN roadmap is shown in Section 7. Common research sites will be decided by FR1 (candidates: Lake Biwa, Kasumigaura, Tokyo Bay, Higashimatsushima, and Shima). The four RUs work together to elucidate the natural and social N cycling, the DPSIR relationship of the N issue (DPSIR is a basic framework of environmental indicators; EEA, 1999; EEA 2005; Fig. 3), and the behavior of stakeholders (producers, consumers, policy makers, etc.) regarding the N issue in each site, and to conduct transdisciplinary research aiming at disseminating awareness of the N issue and planning sustainable N use for the future. Causal N analyses in district and national scales are also conducted. Natural Cycling Unit is conducting a nationwide survey of streamwater chemistry in 2022 to analyze its changes compared with that in ca. 20 years ago. Human Society Unit will conduct the N budgets and input–output analysis and construct future scenarios of N use. Economic Evaluation Unit will conduct social N cost evaluation and behavior analysis of consumers and producers. Future Planning Unit will achieve the three breakthroughs on a national scale without limiting the site and will cooperate with the international activities by UNEP and INI.

Fig. 3. Driver–Pressure–State–Impact–Response (DPSIR) framework applied to one aspect of the nitrogen issue, i.e,. atmospheric transportation, deposition, and exposure as an example. 

4) Expected results

The following are expected: substantial enhancement of interdisciplinary knowledge (e.g., spatiotemporal relationship between streamwater chemistry and Nr emissions nationwide, N flow in human society and Nr emissions to the environment, and social costs of N pollution measures, etc.), collaborative research results in natural and social sciences (e.g. social experiments underpinned by natural sciences, economic evaluation of indicators such as N footprints and utilization for behavioral change, an N-DPSIR visualization tool, etc.), various narratives based on inter- and trans-disciplinary knowledge (e.g. SusN leaflet with the fact of the N issue, questionnaire on N and environmental issues and environmentally friendly behaviors and its application results to high school and university students, RIHN CRs N Review, various specialized books, JNA, etc.), and ideas for sustainable N use obtained from FD practices with domestic and foreign stakeholders (Fig. 4). As related events, INA is scheduled to be published in the middle of FR1, and PL is planning to invite the INI Conference to Kyoto in the latter half of FR4.

Fig. 4. Expected outputs and outcomes of the Sustai-N-able Project.

5) Project organization and membership

SusN consists of three RUs in charge of interdisciplinary research (Natural Cycling, Human Society, and Economic Evaluation) and one RU in charge of transdisciplinary research (Future Planning). The three interdisciplinary RUs strive to deepen research in their respective study fields, while also conducting research in cooperation at the common research sites to accumulate cross-disciplinary knowledge on the N issue. Future Planning Unit collaborates with the other RUs to co-create inter- and trans-interdisciplinary knowledge with other stakeholders. Future Planning Unit sets up several missions, e.g., activities on N recognition, forming respective teams from interested members from all RUs. Each unit has a unit leader. Since Future Planning Unit is responsible for the integrated task of co-creating transdisciplinary knowledge, PL takes a role as the leader of this unit. The composition of leaders and members (as of 24 December 2022) is shown in Fig. 5.

Fig. 5. Research units and members of Sustai-N-able Project (as of 24 December 2022).

Challenges and achievements for this year

2. Project progress during the PR period

1)  Project overall progress

l  Methodological development and organization formation

At the beginning of FS, the scope of SusN was narrowed to the N cycling of food system as the maximum N use. However, the N issue is closely related to all human activities such as food, goods, and energy, and new N use for energy sources is emerging. Therefore, the SusN policy was changed to cover all the N use and has been working on the methodological development and organization formation on this revised policy since the second half of FS.

Many unknowns remain on the N issue, such as the N dynamics in the environment, the relationship between N flows in human society and the environment, the economic effects of measures on the N issue, and response of social human behavior to the N issue. In addition to collecting the state-of-the-art knowledge in each field, we also need to be at the forefront of interdisciplinary research. The following are needed to realize the movement towards sustainable N use; supporting decision making, raising awareness of the N issue, and facilitating open-ended ideas to enable sustainable N use for future generations. These are the three breakthroughs that SusN is aiming for, i.e., N-DPSIR, N recognition, and future N planning. To achieve them, it is necessary to integrate the existing and new interdisciplinary knowledge and to co-create and practice transdisciplinary knowledge with other stakeholders. Three interdisciplinary RUs, i.e., Natural Cycling, Human Society, and Economic Evaluation, aim for deepened research in each field. One transdisciplinary RU, i.e., Future Planning, aims for achieving the breakthroughs working together with the other RUs. The three interdisciplinary RUs develop existing methods and elucidate unknowns related to the N issue (e.g., fate of Nr lost to the environment, linkage between N flow and industrial economy, effect and cost evaluation of abatement technologies, behavior of consumers and producers on the N issue, etc.). The basic method of Future Planning Unit is to set specific missions for each of the three breakthroughs, and work on them by each team consisting of project members (e.g., cost–benefit analysis [CBA], questionnaire on N and environmental issues and environmentally-friendly behavior and its application in educational opportunities, and FD with various domestic and international stakeholders, etc.). New ideas for missions can be born independently or in relation to other programs and projects, and effective missions will be added and implemented as needed as SusN progressing. SusN also emphasizes cooperation with programs and projects in Japan and overseas, e.g., RIHN FD Project, RIHN Supply Chain Project, JST COI-NEXT Gastronomy-Geopolitics Project (PL: Matsubae, leader of Human Society Unit), AIST Moonshot (PL: Kawamoto), life cycle impact assessment (LCIA) method LIME (PL: Itsubo), International N Management System (PL: M. Sutton), UNEP, INI, and Task Force on Reactive N (TFRN) of the Convention on Long-Range Transboundary Air Pollution.

SusN has placed a high priority on forming interdisciplinary research organization linking various experts to cover the entire N issue. Leading experts in fields such as biogeochemistry, isotopic chemistry, environmental engineering, industrial ecology, agriculture, agricultural economics, environmental economics, life history, and policy studies, as well as food culture and environmental education have formed the three interdisciplinary RUs and one transdisciplinary RU of SusN. Considering the suggestion of EREC at the evaluation for FR, SusN has expanded its comprehensiveness by bringing in new experts especially for policy studies and environmental economics. To encourage the commitment of young researchers who will be key persons to address the N issue in the future, doctoral students have joined SusN, and four postdoctoral researchers will be hired as RIHN researchers from FR1.

Research achievements in PR are explained in Section 3, 1). The following are key achievements in FS. On the breakthrough (1) N-DPSIR, Japanese N budgets from 2000 to 2015 were published (Hayashi et al. 2021a; joint press release by RIHN). On the breakthrough (2) N recognition, a symposium at the annual meeting of the Japanese Society of Soil Science and Plant Nutrition (ca. 150 participants), a joint online international workshop with the INMS and South Asian Nitrogen Hub (33 participants), and the 1st Nitrogen Cycling Symposium (ca. 450 participants; co-hosted by RIHN) were held. A picture book on the N issue was published (Hayashi et al. 2021b). On the breakthrough (3) future N planning, based on the experience of conducting two FD sessions in collaboration with the core FS (principal investigator: Nakagawa), it was convinced that FD can be a promising approach to address the N issue and the PL (Nakagawa) of the RIHN Strategic Program FD Project joined SusN as a member of Future Planning Unit.

l  What part of the project results was achieved

Of the three breakthroughs, (1) N-DPSIR, the applicability of the DPSIR framework (EEA 1999, EEA 2005) was discussed in FS, and information of the CBA of the N issue in INMS was collected. Due to the COVID-19 pandemic, INMS has been delayed greatly, and its CBA was also delayed and will be opened in 2023. Therefore, SusN will start CBA on the N issue and causal analysis of N use and N pollution from FR1. Regarding breakthrough (2) N recognition, SusN organized a talk event with citizens in IS, the 1st Nitrogen Cycling Symposium with AIST Moonshot in FS. In PR, SusN again organized the 2nd Nitrogen Cycling Symposium with AIST Moonshot (ca. 320 participants; co-hosted by RIHN). As materials to tell people the N issue, a picture book (Hayashi et al. 2021b) was published in FS. In PR, a project leaflet with the fact of the N issue and questionnaire on the N and environmental issues and environmental behavior are being created. From the initiation of SusN, many opportunities of talks on the N issue with students and public were conducted. Regarding breakthrough (3) future N planning in PR, we visited ministries of the government of Japan (agriculture: MAFF, environment: MOE, economy: METI, and land and infrastructure: MLIT) for discussion on the N issue and worked on dissemination and practices of FD. Regarding collaboration with other programs and projects in PR, a talk event was co-hosted with Gastronomy-Geopolitics Project. SusN was registered as an approved project of the iLEAPS-Japan (iLEAPS-Japan 2022), INMS (INMS 2022b), and INI, respectively in 2022.

l  Noteworthy progresses beyond the initial plan

The press release of Japanese N budgets in FS had the effect of spreading awareness of the N issue through inquiries from ministries and the media. The two times of Nitrogen Cycling Symposiums co-hosted by RIHN in collaboration with AIST Moonshot were also effective to expand interest in the N issue among various stakeholders. Visiting the ministries of the government of Japan was successful to include the necessity of comprehensive N management in the Environmental Research and Technology Development Fund FY2023 under the jurisdiction of the Ministry of the Environment (MOE). We proposed a project “Research on Comprehensive N Management to Reduce N Waste” (under review as of December 2022). PL was appointed as the director of the INI East Asia Regional Centre, which ran for early PR and SusN was a strong appeal to INI. Details of special items in PR are described in 3. 2).

l  Problems faced and their solutions

Research delays due to COVID-19 impacted on the activities IS, FS, and the first half of PR. The development of plan and organization of SusN had been depended on mainly online discussions instead of in-person meetings. Other collaborative programs and projects were also delayed by COVID-19, especially in the CBA of INMS, which is planned to be referred to the breakthrough (1) N-DPSIR. CBA of SusN will start from FR1 learning from the INMS method and improving it with specific themes (e.g., CBA of N pollution treatment). Business trip and in-person meetings have become possible since the first half of PR, so we are actively working to catch up. In particular, the PR meeting held in early November 2022 was a great opportunity for the members to interact and solidify our research plans.

2)  Amendments to research objectives, methodology and organization as applicable

There are no changes to the research objectives and methods. However, during the PR period, we are working to improve our research plan and organization with special emphasis on strengthening collaboration among the four RUs, to which RU leader meetings are held twice a season. As a change in the organization structure, Shibata, who is the sub-leader (SL) of SusN and co-unit leader of Future Planning Unit, will resign at the end of PR due to personal reasons. Although the SL is an important role, we do not rush to find a successor since having one unit leader as SL and another new unit leader or having another unit leader concurrently serves as SL has a significant impact on the progress of project. SusN will proceed without SL for a while, at least during FR1. In addition, each unit leader is requested to appoint sub-unit leader(s) as necessary to support the activities of each RU.

3. Self-diagnosis of research results in this year

1)  Results achieved this year

Review papers were main academic results in PR (Hayashi 2022; 2023a, Pedersen et al. 2022). An opinion paper on the environmental concerns of NH₃ fuel (Nishina 2022) and books and articles to tell the importance of N issue (Hayashi et al. 2021b; 2023b) were also published or written. An academic paper on the damage factor of the potential impact on human health of stratospheric ozone depletion by nitrous oxide emissions was submitted (Hayashi and Itsubo, major revision) that will be useful for both LCIA and CBA of the N issue. A specialized book “Economics of Sustainable Agriculture (tentative)” is in preparation to be published in 2023.

SusN is supporting the Health Check of Mountains Project (FSERC 2022) that conducts survey of streamwater chemistry with ca. 1300 points nationwide Japan using a citizen science method. This survey precedes the similar nationwide survey planned by Natural Cycling Unit in FR1. SusN will be able to clarify the achievement of this survey in FR. Human Society Unit provided preliminary life cycle analysis of the electric furnace method useful for iron recycling that using NH₃ as an energy source may rather reduce the total Nr loss to the environment compared to conventional energy sources. On activities related to N recognition, seminars on the N issue were held at several Japanese ministries. SusN proposed “Nitrogen” as a theme of the One Poster per Household project of the Ministry of Education, Culture, Sports, Science and Technology (MEXT). Although it was rejected at the final selection, we will rechallenge in FR1. PL received many offers for presentations on the N issue at academic conferences and lectures for students. SusN co-hosted the online talk event of the Global Gastronomy Day together with Gastronomy-Geopolitics Project and Tsuji Culinary Institute and co-hosted the 2nd Nitrogen Cycling Symposium with AIST Moonshot. For activities related to FD, which will be an important approach to realize future N planning, the results of the FD session on NH₃ fuel are being compiled as an opinion paper together with SusN and RIHN FD Project. The two projects produced a movie (Japanese and English versions) that tells people the thoughts of a natural scientist who met FD first (Nakagawa et al. 2022), are creating a teaching and questionnaire material on the rice consumption in Japan now and after 30 years from now, and will have an FD seminar with the INI Steering Committee members (scheduled on 26 Jan. 2023).

2)  Results can be evaluated as having overfulfilled

In February 2022 at the latter half of FS, PL had the opportunity to hold an online study session with the Ministry of Agriculture, Forestry and Fisheries (MAFF), Japan to explain and discuss the N issue (ca. 30 participants). This was also in response to a request for advice from MAFF on the draft resolution of sustainable N management just before the UNEA-5. In the first half of PR, PL, Nishina (Natural Cycling Unit, National Institute for Environmental Studies [NIES]), and Kawamoto (AIST Moonshot Project Manager) collaborated to have study sessions on the N issue with MOE, METI, and Ministry of Land, Infrastructure, Transport and Tourism (MILT), respectively. In particular, the online session with MOE was attended by 65 people including the director general class. After that, through several inquiries from MOE, an administrative need for research theme “Development of a comprehensive management method for air, water, and soil with respect to N” was listed in the application guideline of the Environment Research and Technology Development Fund FY2023. Nishina took a role as the project leader and applied to this fund as “Research on Integrated N Management to Reduce N Waste.” Several SusN members including PL joined this proposal also aiming collaboration with SusN and NIES. If adopted, the three-year project from FY2023 will establish a standard method of Japanese N inventory, set N waste reduction targets, evaluate the effects of comprehensive N management policies, and create N waste reduction scenarios in Japan and Asia. Its achievement will contribute to the three breakthroughs of SusN greatly. It is expected that MOE is responsible for the national focal point of the UNEP NWG in, which is not established in Japan. In this regard, our response to the administrative need of MOE for a comprehensive N management is of great significance. It is evaluated that our activities to promote the interest of related ministries have achieved more than the target.

INI, an international expert group on the N issue, consists of its headquarters (now in the USA) and regional centres (Europe, North America, South America, East Asia, South Asia, Africa, and Oceania). In the summer of 2022, PL ran for the director of the East Asia Regional Centre. As a result, PL was elected as the director, first time from Japan, and the renewed centre with Baojing Gu (Zhejiang University) from China as the vice-director started in November 2022 (up to three years × two terms that covers the entire FR period). The past East Asia Regional Centre covered only Japan, China, and South Korea, but as a policy of PL, we aim to expand our network to engage experts in Southeast Asia such as Malaysia, Thailand, Indonesia, and Vietnam, etc. A mailing list was prepared for this purpose. The regional center directors are also members of the INI Steering Committee (SC) and are actively involved in international activities related to the N issue. INI has been responsible for planning the INMS project and supporting UNEP on international N management. The PL’s commitment to INI gives great power to SusN’s international activities, especially the development of transdisciplinary research such as FD with international stakeholders. PL also participated in the INI SC meeting held in October 2022 in conjunction with the 21st International N Workshop in Madrid. At the SC meeting, PL proposed ideas of making SusN as an approved project of INI and inviting the INI Conference to Kyoto after the next (New Delhi in the end of 2023 or the beginning of 2024), received interest. The selection of the INI Regional Centre directors was based on an examination in the INI SC. It is interpreted that the selection of PL as the director was the result of expectations for the concept and outcome of SusN. PL appreciates that the activities aimed at promoting international collaboration of SusN have progressed far beyond the target.

3) Points to be evaluated that the goals were not reached

The impact of COVID-19 remained even during the first half of PR. It was difficult to hold in-person meetings both in Japan and overseas. For this reason, progress in the breakthrough (1) N-DPSIR has been delayed. In PR, we planned to examine the CBA methodology of the INMS project. However, INMS was also delayed due to COVID-19 in addition to the limited opportunities for discussion in SusN. From FR, we will start CBA with specific themes using existing data (e.g., CBA for N pollution treatment). Our policy is to gradually increase the skills and experience of CBA. On the breakthrough (3) future N planning, we proposed seminars and practical opportunities for FD to UNEP, but there has been no response at present. Since it is expected that activities such as the UNEP NWG will become more active before the UNEA-6 (February 26 to March 1, 2024), we will propose it again in FR1. On the other hand, since INI experts are interested in N communication using FD, we are organizing an FD seminar in late January 2023.

4) Notable achievements and challenges as to contribution to the RIHN programs

The SusN breakthrough (1) N-DPSIR, evaluating the benefits of N use and the threats of N pollution to support decision making on sustainable N use, contributes to the first mission of the Program 3 aiming to clarify the relationship and links between various human activities and nature, and to reduce the antinomy and increase the synergy. N-DPSIR also covers multi-spatial scales of the N issue such as local, national, Asian, and global, and contributes to the 3rd phase Program 3. The breakthroughs (2) N recognition and (3) future N planning aim at sharing interdisciplinary knowledge on the N issue with various stakeholders, co-creating transdisciplinary knowledge such as various narratives and designing sustainable N use using FD, etc. They match the second and third missions of the Program 3 and contribute to the progress of the program. On the breakthrough (3), SusN collaborates with the Strategic Program FD Project to apply the FD methodology to design sustainable N use. In this aspect, SusN contributes to the 3rd phase Program 3 by inheriting and evolving the FD methodology developed under the program. In addition, the analysis of the choice and behavior of producers and consumers in SusN Economic Evaluation Unit well match the missions of the Program 2 and contributes to the program. A noteworthy achievement in PR are the efforts to put FD into practice in Japan and overseas in cooperation with the FD Project, an opinion paper (in preparation) of future NH₃ fuel derived from a series of FD sessions with domestic experts, and a movie to tell the thoughts of a natural scientist who encountered FD (Japanese and English versions, Nakagawa et al. 2022).

Future tasks

5. Research plan for next year

Natural Cycling Unit: (1) Investigation of the N removal capacity and ecosystem responses to the N loads of Tokyo Bay, emphasizing items for which observations and information are lacking. Lake Biwa, Kasumigaura, and Akkeshi Bay are possible comparison sites with Tokyo Bay. (2) Sample and data analysis of the Health Check of Mountains to compare the status between years of 2003 and 2022 and to elucidate the relationship between the streamwater chemistry and N deposition and the impact of N deposition on the forest ecosystems. (3) Supporting other RUs, e.g., providing the N removal parameters to analysis of Economic Evaluation Unit using the InVEST model. (4) Promoting N recognition from the viewpoint of natural science in collaboration with Future Planning Unit.

Human Society Unit: (1) On the food system, modification of the nutrient-extended input–output model by sectoral refinement and connection with regional input–output tables, and analysis of the local-scale N flow associated with consumption. (2) On the industrial and energy sectors, analysis of the N flow of steel and semiconductor industries. For the steel industry, comparison between a conventional method and methods using hydrogen and NH₃ (for the latter, direct use for steeling and indirect use for power supply). For the semiconductor industry, detailed N inventory analysis for the demand of high-purity industrial gases. (3) On future scenarios, collection of information on future in the industrial sector. (4) Development of a common analysis tool for the common research sites.

Economic Evaluation Unit: (1) Pre-experiment using a randomized controlled trial to determine the behavioral insights effective in encouraging consumers to choose plant-based food attracting attention in terms of health and environmental measures. (2) Analysis of the results of the online choice experiment of milk consumption in the end of PR on the relationship between the N measures and choice behavior of consumers. Nudge analysis comparing control (no additional information), intervention 1 (environmental information), intervention 2 (heath information), and intervention 3 (environmental and health information) groups. (3) Examination of N reduction scenarios to analyze the willingness to pay of citizens for water quality improvement, using the InVEST model to develop the scenarios. Target areas will be Lake Biwa and Tokyo Bay. (4) Publication of a book “Economics of Sustainable Agriculture” for public that reviews past research achievements and returns the PR and FR1 results to society.

Future Planning Unit: (1) On the breakthrough N-DPSIR, trying CBA on N pollution treatment as a case study, application of LCIA methodology to the N issue, and planning the N-DPSIR method learning from the CBA of INMS Project. (2) On the breakthrough N recognition, beta version completion of the questionnaire on N and environmental issues and environmentally friendly behavior and its application to lectures for high school and university students. Reproposing the N poster to MEXT. Outlining the RIHN CRs N Review. Consideration of production team of JNA involving experts from SusN and other programs and projects. (3) On the breakthrough future N planning, creating practices of FD sessions with domestic and international stakeholders (e.g., farmers in Kyoto Prefecture, experts in UNEP and INI, etc.). Several dialogues with various stakeholders in collaboration with the SusN members to achieve the breakthrough N recognition and to increase future opportunities of FD with them. Consolidation of collaborations with domestic and international programs and projects.

6. Tasks for the next fiscal year onward

1. The problems and challenges that project faced this year and their possible solutions.

Integration of the ID knowledge on the N issue through active cross-disciplinary collaboration is needed to achieve the breakthrough (1) N-DPSIR. Collaboration within SusN, i.e., between RUs and inside each RU, has progressed slowly mainly due to the difficulty in deep discussions under the COVID-19 pandemic. We are catching up with free discussion opportunities (e.g., monthly lunch-on meeting in Natural Cycling Unit and Unit Leaders meeting twice a season, etc.). Future Planning Unit has started several missions (e.g., project leaflet with brief introduction of the N issue and questionnaire on the N and environmental issues and environmentally friendly behavior), where members of each mission are solicited from all RUs. This approach is effective in strengthening inter-unit collaboration and individual interactions. It is also expected that the latter can be a source of new spinoff research ideas.

2. Particular issues regarding the RIHN support system for project research.

Supports of RIHN are expected to use the information and data accumulated by RIHN for the analysis of common research sites (particularly Lake Biwa) and the CRs N Review. The duty of PL as the INI East Asia Director from November 2022 is voluntary and do not require much support; however, close cooperation with RIHN is highly appreciated with respect to international networking in East and Southeast Asia and project proposals on N communication, etc., since they are beneficial to achieve the RIHN’s international aims. PL has a plan to invite the INI Conference to Kyoto after the next, expected in autumn 2026. If the INI Conference in Japan, first time ever, is co-hosted by RIHN with other Japanese academic societies and INI, that will be an epoch for RIHN. PL envisions that JNA as the final product of SusN will be produced as a compilation of the state-of-the-art knowledge on the N issue in collaboration with other related programs and projects and published as a book of the RIHN Book Series (in English) and Summary for Policy Makers (in Japanese). PL would like to start consultations with relevant parties. Cooperation with activities where RIHN plays a central role in networking such as the University Coalition for Carbon Neutrality and Future Earth is also expected.

Progress and Results (2023 Year)

Research purpose and content

1. Executive summary

1) Objectives and background

Sustai-N-able (SusN) Project targets the nitrogen (N) issue that is a tradeoff between the benefits of N use as fertilizers, industrial materials, and energy sources and the threats of N pollution from local to global scales (Fig. 1). The purposes of SusN are to create a universal and globally applicable methods for assessing the N issue, future scenarios, and inter- and trans-disciplinary knowledge to address the N issue focusing mainly on Japan, but also in cooperation with international activities to resolve the N issue in 2050 with food equity and good health of humanity and nature supporting the international N management initiated by the United Nations Environment Programme (UNEP). SusN tries to achieve the following three breakthroughs during 5-year period: (1) developing a framework to visualize the benefits of N use and the threats of N pollution based on scientific knowledge of the driver–pressure–state–impact–response (DPSIR) of the N issue (N-DPSIR), (2) promoting recognition of the N issue still not well known among various stakeholders (N recognition), and (3) designing sustainable N use in the future (future N design).

Fig. 1. Nitrogen issue is a tradeoff between nitrogen use (benefits) and nitrogen pollution (threats).

N pollution causes various impacts such as climate change, stratospheric ozone depletion, air pollution, water pollution, eutrophication, and acidification. The annual damage cost due to N pollution in 2000s in the world was estimated to be 340–3400 billion USD (UNEP 2019a). The amount of anthropogenic creation of reactive N (Nr, N compounds other than inert and harmless dinitrogen [N₂]) now exceeds the natural creation (Fowler et al., 2013). However, the N use efficiency (NUE) of human activities is low, ca. 20% in the world (Sutton et al., 2013). A large amount of N waste is generated eventually, part of which lost to the environment as Nr causing the N pollution. It has been assessed repeatedly that the human alternation of the global N cycling has already transgressed the planetary boundaries (Rockstörm et al., 2009; Steffen et al., 2015; Richardson et al., 2023).

The world mean NUE of crop production is ca. 50% and that of livestock production ranges from 5% to 20% (Lassaletta et al., 2014; Bouwman et al., 2013). Preference for animal products, therefore, lowers the food system NUE, and food loss wastes all the N input to produce the lost food. Economic disparity of fertilizer availability results in regions with too much and too little N in the world. Places of production and consumption often cross borders, causing that consuming countries eventually contribute to the N pollution in producing countries. Global N waste has been increasing since 1961, approximately four times in 2005 and will be six times in 2050 compared to that in 1961 (Sutton et al., 2021). Agricultural N input in 2050 will increase to support future food demand that intensifies the surplus N in croplands (Mogollón et al., 2018). A new N use as fuel ammonia (NH₃) is being created (Nishina, 2022). In addition to watching future progress, our N use should be shifted more sustainable one to mitigate the threats of N pollution.

N waste in Japan from 2000 to 2015 was ca. 6 Tg N yr^–1, and its per capita value was approximately double of the world mean (Hayashi et al., 2021a). More than 80% of the N waste in Japan originated from the imported commodities. Therefore, limited opportunities are available for N recycle within the nation, and the exporting countries suffer N pollution during the production of exports. N flow analysis of fish products is also important in Japan because those account for ca. 20% of the food N supply. Although the NUE of fish products can be hundreds of percent owing to natural catch, the sustainability of fishery resources is essentially important. The Nr lost to the environment has showed a decreasing trend in Japan, where the decrease in nitrogen oxides (NO_X) from transportation sector was remarkable. Meanwhile, Japan focuses on NH₃ fuel in the momentum of decarbonization because combusted NH₃ does not create carbon dioxide. The Ministry of Economy, Trade and Industry (METI) announced a plan in September 2021 that 25 Tg N yr^–1 of NH₃, corresponding to 18% of the world NH₃ production in 2015, will be supplied for fuels in 2050 (METI, 2021). NH₃ supply for Japan will rely on import due to cost efficiency. There are concerns of economic competition among N uses and of N pollution due to NO_X emissions from combusted NH₃ and leakage of NH₃ to the environment. The future N use in Japan is uncertain and its change will spread to the world via international trade. It is expected that policy, technology, and behavior changes for sustainable N use in Japan will contribute to solving the world’s N issue.

The International Nitrogen Initiative (INI), officially launched in 2003, is an expert group to tackle the N issue. INI plans international projects, supports international organizations, and hosts international N conferences on a 3-year basis regularly so far except the 8th conference affected by COVID-19 (INI, 2023). The project leader of SusN (PL, hereinafter) has served as the director of INI East Asia Regional Centre from November 2022. SusN will cooperate with INI closely. UNEP was the implementing body of the International Nitrogen Management System (INMS) project, planned by INI, to apply scientific knowledge to international policy (October 2017–June 2023; INMS, 2023a). PL and some SusN members had contributed to INMS as co-leads and members. In conjunction with the United Nations Sustainable Development Goals, INMS has set a goal of halving the N waste and will publish the International Nitrogen Assessment (INA) in July 2024 as the final product of INMS. PL is one of the INA editors and authors, and some SusN members are INA authors. It is recognized that SusN is a spinoff of INMS (INMS, 2023b). The Resolution on Sustainable Nitrogen Management was adopted twice at the 4th and 5th United Nations Environment Assemblies (UNEA) (UNEP, 2019b; 2022). 6th UNEA (UNEA-6) is scheduled for February 26 to March 1, 2024, and it is expected that international consensus on sustainable N management will be accelerated. UNEP established the Working Group on Nitrogen (WGN) to build consensus among participating countries (UNEP, 2023). The Ministry of the Environment (MoE), Japan has also joined in WGN since 2022 as a focal point of Japan. SusN PL and members are supporting WGN activities of MoE from 2023, here connecting the Ministry of Agriculture, Forestry and Fisheries (MAFF), Japan with respect to food security aspects.

N research has progressed in individual fields, e.g., natural N processes, environmental monitoring, industrial N uses, N footprint, and agro-environmental policies, etc. However, further research is needed to address the N issue, e.g., responses of natural ecosystems to changes in N flow, N flow in human society and its future changes, effects of policy, technology, and behavior changes on the N issue, and a framework to support decision making by visualizing the N-DPSIR. Transdisciplinary (TD) research with multi-stakeholders to design sustainable N use is essential because N is deeply linked to all human activities through food, goods, and energy. It is expected that the Future Design (FD), attracting attention as a method to co-create ideas to solve issues from the perspective of future generations, is useful for creating ideas to realize sustainable N use. SusN is collaborating with the RIHN Strategic Program FD Project (PL: Nakagawa) to apply FD with supports of Saijo, the former director of the RIHN 3rd phase Program 3.

2) How does the research contribute to the solution of the global environmental problems? 

SusN aims to deepen research in each field on the N issue and to make the following three breakthroughs: (1) N-DPSIR, (2) N recognition, and (3) future N design. N-DPSIR will provide a tool for evaluating and visualizing changes in N use and N pollution due to changes in policy, technology, and behavior. N recognition will compile the latest interdisciplinary knowledge (e.g., Japanese Nitrogen Assessment [JaNA] and books of specific fields), TD knowledge (e.g., project brochure with key facts of the N issue and narratives as movies and reading materials), and approach to various stakeholders using the created narratives. Future N design will practice FD with various domestic and international stakeholders (e.g., policy makers, experts, consumers, and producers, etc.) and promote collaboration with international organizations such as UNEP and INI. The difficulty in balancing the benefits and threats has hampered the resolution of the N issue. SusN will provide quantitative information on the effects of various countermeasures and behavioral changes based on the causal relationship between N use and N pollution. SusN will provide opportunities for future generations to come up with ideas for the sustainable N use. As a result, it is expected that awareness of the N issue will increase both domestically and internationally, the existing and new initiatives for sustainable N use are strengthened, and the breakthroughs to resolve the N issue are achieved.

3) Methodology, structure and schedule

The N issue encompasses all human activities and the environment, and many questions remain unsolved. Therefore, the first pillar of SusN is to accumulate the latest knowledge of the N issue covering nature and human society, and to conduct interdisciplinary research at the forefront, e.g., field survey, laboratory experiments, numerical analysis, questionnaire surveys, data preparation, and scenario construction, etc. It is needed to support the policy makers and each stakeholder to address the N issue not well recognized like the case of climate change 30 years ago. A framework is needed to create ideas freely to permeate the awareness of N issue and realize sustainable N use for future generations, to which the three breakthroughs, (1) N-DPSIR, (2) N recognition, and (3) future N design contribute. The second pillar is TD research that integrates existing and new interdisciplinary knowledge and co-creates TD knowledge with other stakeholders to achieve the three breakthroughs. The third pillar is to cooperate with domestic and international N-related programs and projects. It is expected that the collaboration with other programs and projects generates many spinoff activities from interactions between those involved, and that new projects towards sustainable N use will be inherited after the completion of SusN.

SusN has three interdisciplinary research units (RUs) to cover all aspects of the N issue that connect nature and human society: Natural Cycling Unit, e.g., provision of knowledge on the environmental N science; Human Society Unit, e.g., analysis of N flow in the production and consumption of food, goods, and energy; and Economic Evaluation Unit, e.g., quantification of social costs of human activities on the N issue such as food production and consumption. SusN also has one TD RU, i.e., Future Design Unit, to achieve the three breakthroughs by working with the other three RUs closely. SusN sets common analysis sites, connects spatial scales from local to global, and conducts research from both bottom-up and top-down approaches (Fig. 2).

Fig. 2. Schematic view of research approach. Three interdisciplinary research units (RUs; natural cycling, human society, and economic evaluation) deepen each research, and one transdisciplinary unit (Future Desing) works to achieve the three breakthroughs, i.e., N-DPSIR analysis, N recognition, and future N challenge, in close collaboration with the other RUs. DPSIR, driver-pressure-state-impact-response; INMS, International Nitrogen Management System; UNEP, United Nations Environment Programme; and INI, International Nitrogen Initiative.

Common research sites are Lake Biwa, Kasumigaura, Tokyo Bay, and Matsushima Bay. The four RUs work together to elucidate the natural and social N cycling, the DPSIR (EEA, 1999; EEA 2005; Fig. 3) relationship of the N issue, and the behavior of stakeholders (producers, consumers, policy makers, etc.) regarding the N issue in each site, and to conduct TD research aiming at disseminating awareness of the N issue and planning sustainable N use for the future. Natural Cycling Unit has been conducting a nationwide survey of streamwater chemistry and elucidating natural N cycling in various ecosystems. Human Society Unit conducts the N budgets and input–output analysis and constructs future scenarios of N use. Economic Evaluation Unit conducts social N cost evaluation and behavior analysis of consumers and producers. Future Design Unit is challenging the three breakthroughs on a national scale and cooperates with the international activities by UNEP and INI supporting Japanese ministries.

Fig. 3. Driver–Pressure–State–Impact–Response (DPSIR) framework applied to one aspect of the nitrogen issue, i.e,. atmospheric transportation, deposition, and exposure as an example.

4) Expected results 

The following are expected: substantial enhancement of interdisciplinary knowledge, e.g., spatiotemporal relationship between streamwater chemistry and Nr emissions nationwide, N flow in human society and Nr emissions to the environment, and social costs of N pollution measures, etc.; collaborative research outputs in natural and social sciences, e.g. social experiments underpinned by natural sciences, economic evaluation of indicators such as N footprints and utilization for behavioral change, an N-DPSIR visualization tool, etc.; various narratives based on inter- and trans-disciplinary knowledge, e.g. SusN brochure with the fact of the N issue, various specialized books, and JaNA, etc.; and ideas for sustainable N use obtained from FD practices with domestic and foreign stakeholders (Fig. 4). As related events, INA is scheduled to be published in July 2024 (FR2), and PL is coordinating with relevant domestic and international organizations to invite the INI Conference to Kyoto in November 2026 (FR4).

Fig. 4. Expected outputs and outcomes of the Sustai-N-able Project.

5) Project organization and membership

SusN consists of three RUs in charge of interdisciplinary research (Natural Cycling, Human Society, and Economic Evaluation) and one RU in charge of TD research (Future Design). The three interdisciplinary RUs strive to deepen research in their respective study fields, while also conducting research in cooperation at the common research sites to accumulate cross-disciplinary knowledge on the N issue. Future Design Unit collaborates with the other RUs to co-create inter- and trans-interdisciplinary knowledge with other stakeholders. Future Design Unit sets up several missions, e.g., activities on N recognition, forming respective teams from interested members from all RUs. Each unit has a unit leader. Sub-unit leader may be set by the decision of the unit leader. Since Future Design Unit is responsible for the integrated task of co-creating TD knowledge, PL concurrently takes a role as the leader of this unit. The composition of leaders and members (as of 15 January 2024) is shown in Fig. 5.

Fig. 5. Research units and members of Sustai-N-able Project (as of 15 January 2024).

Challenges and achievements for this year

2. Project progress during the PR period to date

1) Project overall progress

l  Research results including methodological development and organizational formation

SusN has tackled N-related research since its initiation including the environmental N cycling, the link between N flow in human activities and the environment, and the economic effects of addressing the N issue and changes in social and human behaviors. To create a movement to resolve the N issue, supports for decision-making such as policies, awareness rising of the N issue, and a framework to create ideas freely to realize sustainable N use for future generations are required. These correspond to the three SusN breakthroughs: (1) causal analysis of N (N-DPSIR), (2) spreading awareness of N (N recognition), and (3) designing the future of N use (future N design). While the Natural Cycling, Human Society, and Economic Evaluation Units are engaged in interdisciplinary research, several specific themes (missions) are set that would lead to TD research by the Future Design Unit to achieved the three breakthroughs, and a team is formed for each mission with participants from all units (and sometimes from outside), e.g., cost-benefit analysis (CBA) of N, analysis of N loads and environmental conditions in the Tokyo metro and bay area, and FD with various stakeholders. Tokyo metro area, Matsushima Bay, Lake Biwa, and Lake Kasumigaura were selected as SusN common research sites, and preliminary observations and numerical analyses are being conducted at each. For example, a measurement campaign throughout the common sites was conducted from November to December 2023 by renting a nitrate sensor that enables continuous on-site measurements. For the Seto Inland Sea, where oligotrophication becomes a problem, PL is approaching a Kobe University group on blue carbon to explore future collaboration. SusN has collaborated with other programs and projects: domestic examples such as RIHN FRs (FD, LINKAGE, Supply Chain), JST COI-NEXT Gastronomy Geopolitics (PL: Matsubae, Human Society Unit leader), Environment Research and Technology Development Fund JpNwst (PL: Nishina, Natural Cycling Unit member), NEDO Moonshot N Cycling (PL: Kawamoto, AIST), life cycle impact assessment LIME (Itsubo, Waseda University); and international examples such as INMS (PL: M.A. Sutton, UK-CEH), UNEP, INI, and the Task Force on Reactive Nitrogen of the Convention on Long-range Transboundary Air Pollution in Europe. SusN places the highest priority to form multidisciplinary linkages to cover the entire N issue. The four SusN RUs consist of leading researchers in biogeochemistry, isotopic chemistry, environmental engineering, industrial ecology, agronomy, agricultural economics, environmental economics, life history, and policy studies, as well as experts in unique activities from TD aspects of agriculture, food culture, and environmental education. In response to the EREC’s comments at the FR selection, efforts have been made to expand the expertise and comprehensiveness of the project, including the participation of agricultural producers interested in a TD approach in addition to those in the fields of policy studies and environmental economics. The project has also included graduate doctoral students and hired young RIHN researchers expecting their growth as keen researchers.

Although SusN once focused on only food production and consumption as the largest N user, SusN has covered the entire N issue since the latter half of FS period including production and consumption of food, goods, and energy involving the emerging new use such as fuel NH₃. In FS, SusN published the Japanese N budgets (Hayashi et al., 2021, joint press release from RIHN) and held a symposium at the annual meeting of the Japanese Society of Soil Science and Plant nutrition, a joint online workshop with INMS and the South Asian Nitrogen Hub, and the 1st Nitrogen Cycling Symposium (the first case that RIHN co-hosted at the FS stage). In PR, SusN had many opportunities to publish reviews, books, and articles on the N issue (e.g., Hayashi, 2022; 2023a; 2023b; Hayashi et al., 2022). A paper on damage factor of nitrous oxide on stratospheric ozone depletion health impacts was published at the beginning of FR1 (Hayashi & Itsubo, 2023). SusN has supported the Mountain Health Checkup project since the late PR (Kyoto University, 2022), i.e., nationwide mountain streamwater survey using citizen science methods. This project preceded that SusN once planned to conduct in FR1. SusN co-hosted talks and symposiums such as the Global Gastronomy Day talk event and 2nd Nitrogen Cycling Symposium. In collaboration with RIHN FD project, we produced movies to convey the thoughts of a natural scientist who encountered FD (Nakagawa et al., 2022) and conducted a choice experiment by creating an educational material to consumers on rice consumption in 2050. From the end of FS to the beginning of PR, we held study sessions on the N issue for MAFF, MoE, METI, and the Ministry of Land, Infrastructure, Transport and Tourism (MLIT), and after several inquiries from MoE, an administrative need on the N issue for the Environment Research and Technology Development Fund was created. That was the seed grown as JpNwst project aiming development of N inventory and N management in Japan. PL also participates in JpNwst as a subtheme leader. PL ran to represent the INI East Asia Regional Centre in Nov. 2022 and was the first Japanese to be selected. In FR1, each research unit actively implemented preliminary observations and analyses in collaboration with other units. Specific results are described in “3. 1) Results achieved this year.”

l  What part of the project goal has been achieved

On the breakthrough 1: N-DPSIR, application of the DPSIR framework to the N issue was discussed in FS and information of CBA case studies in the INMS project was collected in PR. We conducted life cycle assessment (LCA) of sewage systems as a study leading to the CBA of N issue in FR1 because the COVID-19 outbreak caused significant delays in the INMS project and then the publication of its final product INA was postponed to FR2. On the breakthrough 2: N recognition, we have worked on planning talk events for citizens from IS and co-hosted the N Cycling Symposium three times in FS, PR, and FR1. Materials were created to tell people the N issue, e.g., “Picture Book of N and the Environment” (Hayashi et al., 2021b) in FS, brochure of the N issue and SusN with illustrations in Japanese and English (SusN, 2023) in PR, and a dialogue article of the N issue in RIHN Newsletter (Hayashi & Abe, 2023; English translation in progress) in FR1. Many opportunities have been given to make lectures and talks on the N issue since IS, and PL feels that interest in N issue is gradually increasing. On the breakthrough 3: future N design, meetings on the N issue have been held with domestic ministries (MoE, MAFF, METI, MLIT), and practices of FD have been done, e.g., movie to introduce FD, FD of fuel NH₃, FD of agriculture in Kyoto Prefecture, and choice experiment of future rice consumption. A planning committee was formed in FR1 to produce JaNA. Coordination with relevant bodies has started in FR1 to invite the 10th International N Conference to Kyoto (Nov. 2026 candidate).

l  Notable achievements beyond the plan

The press release of the Japanese N budgets in FS triggered interest from the government agencies and media. After meetings and inquiries from MoE and MAFF between PR and FR1, a structure was put in place in the late FR1 for SusN members to provide central supports to the national action plan on N management by the government of Japan. The selection of PL as the director of INI East Asia Regional Centre in PR is seen as an expectation to SusN and PL contributing to addressing N issue. SusN members are also contributing to the international N management implemented by UNEP through its WGN.

l  Challenges faced and solutions

The restriction to travels and in-person meetings due to the COVID-19 pandemic was eliminated in early FR1, and the speed of research has returned since then. However, its impacts remained and the publication of INA as the final product of INMS project will be delayed to FY2024 (FR2). Since the international CBA of N issue in INA is good information to refer to achiever SusN breakthrough 1: N-DPSIR, we are working on a preliminary study of CBA of sewage systems in collaboration with LCA researchers, anticipating catch up when INA is published in FR2.

2) Amendments to research objectives, methodology and organization as applicable

Both research objectives and methodology are unchanged; however, the research plan and organization have been elaborated as necessary, and new members have been joined. Bimonthly unit leader meetings are held to facilitate unit cooperation. Although the SusN subleader (also the co-leader of the Future Design Unit) retired with PR, that post is vacant at this time because appointing one of the unit leaders as SL or having one of them as the subleader concurrently will be a root of confusion. On the other hand, subleader is an important post for sharing project traction and hedging risk, and PL therefore continues to look for a replacement.

3. Self-diagnosis of research results in this year

1) Results achieved this year

As achievements of the N-DPSIR, papers of review on groundwater nitrate pollution (Hayashi, 2023c), stratospheric ozone depletion impacts by nitrous oxide (Hayashi & Itsubo, 2023), food supply-chain impacts due to Russia-Ukrainian War (Zhang et al., 2023), sociological analysis on the tradeoff between food production, water use, and climate change (Kyoi et al., 2023), and decreasing resilience of nitrogen-phosphorus cycling network in China (Luo et al., 2024) were published. The significance of collecting streamwater nationwide with volunteer climbers was summarized (Makino et al., 2023) and a paper of the Mountain Health Checkup using this approach with the nationwide distribution of nitrate concentrations was submitted (under review). “Economics of Sustainable Agriculture” (Kuriyama, 2024) will be published within FR1. Seven presentations from SusN were submitted to the 9th International N Conference in New Delhi in Feb. 2024. Each unit’s efforts are ongoing as planned. On unit cooperation, Tokyo Bay area, Matsushima Bay, Lake Biwa, and Kasumigaura were selected as common sites, preliminary measurements and data analyses were conducted there. As a study of CBA for N, an LCA analysis for sewage systems is done with LCA experts. We are working with University of Virginia team that developed the N Footprint Calculator to add Japanese contents to their website (N-Print, 2023) to enable calculation of the N footprint of Japanese people (to be opened within FR1).

As achievements of the N recognition, the brochure of SusN and N issue produced at the end of PR (Japanese and English; SusN, 2023) was actively distributed (ca. 1500 in total). A dialogue on the N issue (Hayashi & Abe, 2023) was published in RIHN Newsletter (English translation in progress, hopefully distributed at the 24th EREC). The editorial board of JaNA was established. RIHN co-hosted events via SusN, of which the 3rd N Cycling Symposium (ca. 650 of participants) was an epoch-making opportunity with speakers and panelists from MoE, MAFF, METI, and MLIT, where PL facilitated the panel discussion on the N use and its challenges in various perspectives, and it was agreed to make a channel for opinion exchange. PL had many speaking opportunities in FR1 and has seen a growing interest in the N issue; major invited talks were at the 10th Acid Rain Conference, 65th Japan Petroleum Institute Meeting, 4th Global Soil Security Conference, Ministry of Education, Culture, Sports, Science and Technology (MEXT)-NIHU Media Meeting, 2023 Symposium of the Association of Japanese Agricultural Scientific Societies, 2023 Symposium of the Inter-University Research Institute Corporation, and Joint Seminar on Water and Atmospheric Environment (Hayashi, 2023d–j). A special feature on N will be published in a booklet in Apr. 2024 for fifth- and sixth-grade elementary school students (Hayashi, 2024), which rooted from a RIHN Media Meeting. SusN implemented many events in collaboration with RIHN Public Relations Unit (PRU) such as open public events, symposiums, MEXT One Poster per Household project (not selected as finalist again; reattempt in FR2), and a series of workshops to visualize and explore leverage points for awareness penetration of the N issue. As a spinoff from the last workshops, a talk event with innovators will be held to consider the N issue by systems thinking under the GREEN×GLOBE Partnership of SMBC Group on 14 Feb. 2024. PL is working to invite the 10th International N Conference to Kyoto in Nov. 2026.

As achievements of the future N design, SusN supported the activities of RIHN Kyoto Climate Change Adaptation Center on FD sessions of agriculture in Kyoto Prefecture. Two papers on the results of FD for NH₃ use and rice consumption are compiled in collaboration with RIHN FD project (submitted). JpNwst project (PL: Nishina) started in FY2023 rooted from the meeting with MoE in PR is complementary to SusN each other, which tackles establishment of Japanese N inventory and evaluation of potentials to reduce N waste. After MoE joined in the UNEP WGN in 2022, PL facilitated a joint meeting with MoE and MAFF on 6 Sep. 2023, which led to lively exchange of opinions between the two ministries and a framework where we experts support their activities has been established. MoE Committee of National Action Plan launched in latter FY2023 is chaired by PL with Nishina and Matsubae participating from SusN (1st on 27 Dec. 2023; 2nd on 13 Feb. 2024; 3rd on 18 Mar. 2024). MoE also established an interministerial liaison with MAFF, METI, MLIT, and the Ministry of Health, Labour and Welfare to let the national action plan be interactive and consistent. PL and Nishina participated to the 4th and 5th UNEP WGN in Sep. 2023 and Jan. 2024, respectively.

2) Results can be evaluated as having overfulfilled

Policy-related stakeholder engagement is being realized in FR1 much faster than expected, which was positioned as a major time-consuming challenge at the beginning of project. In Japan, the approach to relevant ministries that we have been making since FS was successful, and a sister project of SusN, JpNwst (FY2023-2025) funded by MoE was adopted at the end of PR. SusN, together with JpNwst, are now able to support the N management of Japan through the elaboration of N inventory, evaluation of the potential for reduction of N waste, visualization of the N issue, and FD practices. MoE launched the Committee of National Action Plan in latter FY2023 after PL served as a link between MoE and MAFF. SusN supports this committee as the chair and members. The MoE liaison on N management with other ministries has the potential of enabling exchange of ideas not only intra-ministry but also inter-ministries. Independently these efforts, PL and RIHN FD project are warming up the idea of FD session in collaboration with the FD team of the Ministry of Finance (MoF) that targets the N issue linking with environmental conservation, land conservation, food security, and energy security in the future of Japan. Channels are also being created to incorporate a perspective of sustainable N use into activities of private sectors aiming food loss reduction and decarbonization, as the GREEN×GLOBE Partnership event planned on 14 Feb. 2024. On the international aspect, SusN has contributed to international N management while supporting the Japanese government on this. PL was selected to run for the INI Steering Committee in 2022 as the director of INI East Asia Regional Centre (3-year term from Nov. 2022; 2 terms allowable that covers the entire SusN FR period). PL’s commitment to INI, which has planned international projects, supported UNEP’s international N management, and hosted international N conferences for 20 years, will empower SusN to develop international activities, especially FD and TD research with international stakeholders. PL had an opportunity to talk about SusN and FD with respect to multi-stakeholder engagement at the 5th UNEP WGN on 9 Jan. 2024 that would be a step toward suggesting FD sessions on international N management in the future. Collaboration with the Acid Deposition Monitoring Network in East Asia (EANET) is also planned as a two-part seminar series (Feb. and Mar. 2024) as requested by MoE, which will grow good collaboration between SusN and EANET.

3) Points to be evaluated that the goals were not reached

The framing of the CBA for the N issue has been delayed. The main reason is the delay of INA publication to summer 2024, i.e., the final product of INMS project containing the worldwide CBA of the N issue. PL is one of the INA editors and recognizes that the INA chapters on CBA are beneficial to SusN. Accordingly, we started LCA and CBA for sewage systems as a study in FR1. Another study was also achieved economic input-output analysis for tradeoffs between food production, water use, and climate change in FR1. These will be connected in FR2 to build a CBA framework for N use in Japan and East Asia, for which collaboration with JpNwst project will be important.

4) Notable achievements and challenges as to contribution to the RIHN programs 

SusN breakthrough 1: N-DPSIR, which aims to assess the benefits of N use and the threats of N pollution to provide information for decision making of sustainable N use, matches with the first mission of the affiliated program “Co-creation of the Earth-human System Program” that aims to elucidate the relationship and linkage between various human activities and nature to reduce the duality and increase synergy. SusN breakthroughs 2: N recognition and 3: future N design, which aim sharing scientific knowledge on the N issue with multi-stakeholders and creating inter- and trans-disciplinary knowledge such as narratives and FD for sustainable N use in Japan and the world, also match with the second and third missions of the affiliated program that methodological development of communications and transformation of the relationship between humanity and nature for a sustainable future, respectively. SusN collaborates with RIHN FD project to apply FD to design sustainable N use. SusN therefore contributes to the Program 3 in the phase 3 that tackled FD development. Furthermore, the food production and consumption aspect of SusN, e.g., selection and behavior of farmers and consumers and effectiveness of agricultural policies, contributes also to the Program 2 in the phase 4 “Combining Knowledge for a Fundamental Innovation of Land Use Program”. Promoting opinion exchanges among PDs and related members is an important issue to get good fruits.

Future tasks

4. Research plan for next year

Plans of each RU and those for achieving the three breakthroughs in FR2 are shown below.

Natural Cycling Unit: 1, set up a system to measure denitrification ability of sediments and slurries and analysis of N isotopic signature of treated wastewater; 2, follow-up investigation of the Mountain Health Checkup sites and meta-analysis of its results together with the survey in 2003 by RIHN CP Environmental Valuation project; and 3, observation and experiments at the common sites and collaborative analysis with other RUs particularly watershed-scale analysis.

Human Society Unit: 1, elaboration of nutrient use efficiency estimation in food systems; 2, N flow analysis in industrial and energy sectors; 3, data and information organization for waste and wastewater sectors; 4, input-output N flow analysis including overseas case studies; and 5, collaboration with the consortium of Gastronomy Geopolitics project to facilitate stakeholder engagement especially in food sectors.

Economic Evaluation Unit: 1, analysis of household budgeting app purchase data for plant-based food focused on its environmental measures; 2, web-based survey of consumers to determine effective measures to increase awareness to the N issue and willingness to pay to address the N issue; 3, survey of farmers based on the results of survey of consumers; and 4, English translation of “Economics of Sustainable Agriculture” published in FR1. 

Future Design Unit: 1 on the breakthrough N-DPSIR, LCA and CBA of sewage systems, design of an N-DPSIR framework learning from the CBA of INA, and evaluation of N flow and the effectiveness of environmental indicators to consumers in a regional scale; 2 on the breakthrough N recognition, production of JaNA determining editors, table of contents, and lead authors, press release of INA when published with Japanese summary, reattempt to the MEXT One Poster per Household, providing opportunities for outreach actively, e.g., session proposal of N communications to the XXII International N Workshop (Aarhus, Jun. 2024) and symposium proposal of N management in Japan with speakers from MoE and MAFF to the annual meeting of the Japanese Society of Soil Science and Plant Nutrition (Fukuoka, Sep. 2024), and preparation for the International N Conference in Kyoto; and 3 on the breakthrough future N design, publication of two papers resulting from the FD sessions on NH₃ use and rice consumption, supporting activities of Kyoto Prefecture, MoE, MAFF, INI, and UNEP, and facilitating cooperation among the RUs.

5. Tasks for the next fiscal year onward

On the point 1, i.e., problems and challenges that this project faced this year and their possible solutions, although collaboration within each RU and between RUs progressed in FR1, efforts still need to brew an atmosphere and structure in which many members freely exchange opinions and work on SusN. PL will continue to promote information sharing and opinion exchanges with unit leaders and encourage unit cooperation missions to further promote members’ involvement. The absence of SL is a matter to be resolved. However, PL will not seek a new SL too quickly but search for suitable candidates through various channels because of the concern that appointing one of the unit leaders as SL or having one of them as SL concurrently will be a source of confusion.

On the point 2, i.e., any particular issues regarding the RIHN support system for project research, the number of events with RIHN PRU is increasing, and hope to encourage this collaboration. We expect cooperation in use of the information and data accumulated by RIHN CPs in analysis for the common sites, especially Lake Biwa. The position of the INI East Asia director that PL takes is beneficial to the achievement of international missions of RIHN such as networking in East and Southeast Asia. Therefore, PL will share relevant information with RIHN, and hope necessary supports from RIHN. PL is working on inviting the 10th International N Conference to Kyoto (early Nov. 2026 candidate), for which PL expects RIHN to co-host a public symposium in the program. Co-hosting the N conference, first opportunity in Japan, will be a valuable achievement of RIHN. JaNA in both Japanese and English versions will be published as books of the RIHN Book Series, hoping supports of RIHN.