旭硝子財団助成研究成果報告2018

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56木下　幸雄68Yukio KINOSHITA森　晶寿69Akihisa MORI農地と農業用水の管理制度設計の検討 −プロパティ・ライツ制度論の適用−(2016採択)Thinking the institutional design for managing farmland and irrigation water in Japan: Comparative institutional analysis based on property rights regimes (Project 2016)タイの環境政策停滞期におけるカドミウム汚染地域農民の代替的生計手段の経済的・環境的持続性(2016採択)Economic and Environmental Sustainability of Alternative Livelihood for Farmers in Cadmium Polluted Area in Thailand amid Stagnated Progress in Environmental Policy (Project 2016)旭硝子財団　助成研究成果報告（2018）農村環境資源の持続性に関わる問題として，農地と水の管理制度のあり方を研究した．まず，日本の農地問題について概観した上，分析の理論的枠組みとしてプロパティ・ライツ制度論について説明した．次に，農地と農地利用権，農業用水と農業水利権のそれぞれについて，管理制度の階層構造とともにプロパティ・ライツとしての不完全性の状況を解明した．また，プロパティ・ライツ制度論を通して2015年までの農地制度の変遷に評価を与えたとともに，農地管理制度と農業用水管理制度の整合性をめぐる複雑な課題を指摘した．本研究が農地政策や水循環政策に対して課題整理に新たな視角を与え，農地および農業用水の管理制度の設計・運用の実務者に有用な知見となることが期待される．This study highlighted institutional design for managing farmland and irrigation water to sustain agri-envi-ronment and resources. First, Japanese farmland issue was briefly described, followed by an explanation of the property rights regimes in part of analytical framework. Then, institutional hierarchies for managing both farmland and irrigation water were revealed, and the property rights attributes of each resource were com-pared across the hierarchies. While this study reviewed major changes in Japanese farmland policy until 2015 through the property rights regimes, it demonstrated degree of consistency relating to management institu-tions between farmland and irrigation water. Furthermore, results from this study could be useful for some policy makers, who design and operate the institutions managing such resources, to present advanced insights and knowledge in farmland policy and water cycle policy.タイ北西部のメーソット郡では，鉱山からの排水が原因とされる汚染により，農地がカドミウムに汚染された．これに対してタイ政府は，バイオエタノール精製工場を建設して農民に健康被害を起こさないサトウキビへの転作を促した．しかし，数年後には農民は再び健康被害を起こしうるコメ生産を行うようになった．本研究の目的は，なぜ農民がコメ生産へと回帰したのかを解明することにある．このために，環境政策を政治経済の文脈から再検討し，現地でのアンケート調査を行った．分析の結果，コメ生産の費用効率性を高めるインフラシステムの存在，サトウキビ生産に不慣れな農民に対する技術的・資金的支援の欠如，政府の当事者意識の欠如と無策が原因であることを明らかにした．In 2002, cadmium contamination in soils was reported at the downstream of the Mae Tao creek in the Mae Sot District in Northern Thailand. Thai government, in response, created the bioethanol plant to encourage farmers to stop rice cultivation and to grow sugarcane. However, farmers gradually resume rice cultivation at the contaminated paddy field not only for their home consumption but also for sales at the market. This paper aims to explore reasons why farmers resumed rice cultivation that increased health risk. In exploration, we revisit environmental policy in Thailand from political economic point of view, and conduct field survey to farmers. Our analysis finds that infrasystem that gives advantage for rice production, lack of technical and financial support that favors sugarcane production, and lack of ownership of and action by the government are the underlying causes.