Evaluation of nutrient load inputs to winter-flooded paddy fields by overwintering Tundra Swan

2018 Fiscal Year Final Research Report

• Project/Area Number: 15K07647
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Rural environmental engineering/Planning
• Research Institution: Okayama University (2018); Shimane University (2015-2017)
• Principal Investigator: Somura Hiroaki 岡山大学, 環境生命科学研究科, 准教授 (90403443)
• Co-Investigator(Kenkyū-buntansha): 森 也寸志 岡山大学, 環境生命科学研究科, 教授 (80252899)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: 物質循環 / 冬期湛水水田 / コハクチョウ / 水環境保全 / 持続可能な農業

Outline of Final Research Achievements

In this study, we evaluated an influence of overwintering Tundra Swan against water quality and soil fertility in winter-flooded paddy fields. In the field survey, we observed the daytime behavior pattern of the birds and understood their activities. We collected surface water in the paddy fields and analyzed water qualities such as T-P and T-N. In addition, the paddy soils before and after overwintering were collected and analyzed pH, EC, T-N, Available-P, and C/N ratio. As results, regarding the water quality, a statistically significant difference was confirmed between the number of staying Tundra Swan and the water quality fluctuation. However, soil fertility and the number of the birds were still unclear.

Free Research Field

地域環境工学・計画学

Academic Significance and Societal Importance of the Research Achievements

農地は食糧を生産する重要な場ですが，私たち人間だけではなく野生動物も利用しています．コハクチョウは毎年１０月中旬頃ロシア極東から日本へ飛来し，３月中旬頃から徐々に帰郷します．越冬するコハクチョウの一部は，冬場に水田内に水を貯める冬期湛水水田を寝ぐらとして利用し，日中は畦畔で休んだり，周辺農地で採餌したりします．水田や周辺農地で多くの時間を過ごすコハクチョウは，糞という分解されやすい有機物の形で栄養塩を水田内や農地へ供給します．コハクチョウの越冬行動を観察し，水域や土壌へ供給された栄養塩量を正しく評価することで営農に生かすと共に，流域内物質循環の解明を通して水環境の保全に繋げたいと考えています．