Visualizing the Impact of Nitrogen Load Reduction on Tropical Islands through the Food Nitrogen Footprint 
―Scenario of Resource-Recirculating Agriculture and Livestock Industry for 30% Reduction of Chemical Fertilizers―

JIRCAS, in collaboration with the National Agriculture and Food Research Organization (NARO), has made a breakthrough in visualizing the impact of reducing nitrogen loading in food systems on tropical and subtropical islands. 

Recent fluctuations in the prices of chemical fertilizers, food and feed have had a significant impact on agriculture worldwide. This impact is particularly pronounced in tropical and subtropical islands that rely heavily on imports. These regions face challenges due to the underutilization of local organic resources rich in nutrients such as nitrogen. These resources often contribute to nitrogen loading in the environment, leading to negative impacts on coastal coral reefs and marine ecosystems.

The study focuses on Ishigaki Island in Okinawa Prefecture, a subtropical island known for its vibrant agricultural and livestock industries. It aimed to assess the nitrogen load of the island's entire food system, including imported food and feed and exported food. The study also explored scenarios for achieving a 30% reduction in chemical fertilizer use, which is a goal of the Sustainable Food Systems Strategy, MIDORI, by maximizing the use of livestock manure on farmland. The results showed that by utilizing 70% of cattle manure on farmland, nitrogen inputs to crop production could be maintained even with a 30% reduction in chemical fertilizer use, ultimately reducing total nitrogen emissions (nitrogen load) on Ishigaki Island by 18%.

Active use of organic resources from the food system on farmland, combined with reduced use of chemical fertilizers, not only increases agricultural productivity, but also contributes to environmental protection. The food nitrogen footprint applied in this study holds promise for similar tropical and subtropical island regions. It aligns with the United Nations Sustainable Development Goals (SDGs) and the Sustainable Food Systems Strategy, MIDORI, and is expected to aid in the development of strategies to address the recent volatility in chemical fertilizer prices.

The results of this research have been published in the electronic edition of Environmental Research Letters (July 11, 2023 JST).

Authors

K Hamada, S Eguchi, N Hirano, K Asada and N Oka

Title

Assessing nitrogen flow and nitrogen footprint in the food system of a subtropical island with a scenario to mitigate nitrogen load impacted by trade–dependent agriculture

Journal

Environmental Research Letters
DOI : https://iopscience.iop.org/article/10.1088/1748-9326/acdf04

JIRCAS President　KOYAMA Osamu

Program Director：

HAYASHI Keiichi (Environment Program)

Principal Investigators：

HAMADA Kosuke (Tropical Agriculture Research Front)OKA Naoko (Rural Development Division)

Press Coordinator：

OMORI Keisuke (Head, Information and Public Relations Office)
Press e-mail：koho-jircas@ml.affrc.go.jp

NARO

Principal Investigators：

EGUCHI Sadao, HIRANO Nanae and ASADA Kei (Institute for Agro-Environmental Sciences, NARO)

 

Press Coordinator：

SUGIYAMA Megumi (Institute for Agro-Environmental Sciences, NARO)
Press e-mail：niaes_kouhou@ml.affrc.go.jp