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Specific property of nitrogen discharge in clayey ex-paddy fields related with decline of soil nitrogen fertility

Research Project

Project/Area Number 26450083
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Research Field Plant nutrition/Soil science
Research InstitutionNational Agriculture and Food Research Organization

Principal Investigator

SUZUKI Katsuhiro  国立研究開発法人農業・食品産業技術総合研究機構, 中央農業研究センター 水田利用研究領域, 上級研究員 (90354068)

Co-Investigator(Kenkyū-buntansha) 中島 泰弘  国立研究開発法人農業・食品産業技術総合研究機構, 農業環境変動研究センター 物質循環研究領域, 主任研究員 (10354086)
Project Period (FY) 2014-04-01 – 2017-03-31
Project Status Completed (Fiscal Year 2016)
Budget Amount *help
¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000)
Fiscal Year 2016: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2015: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2014: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Keywords粘土質転換畑 / 窒素流出 / 脱窒 / 溶存有機態窒素 / 窒素・酸素安定同位体比 / 窒素肥沃度 / 硝酸態窒素 / 懸濁態窒素
Outline of Final Research Achievements

Recently, declining yields are of concern in the ex-paddy fields, that were previously used to cultivate paddy. We investigated the specific properties of nitrogen (N) discharge in clayey ex-paddy fields related with decline of soil N fertility.
Nitrate was the main form of N in tile drainage. Nitrate concentrations decreased gradually during each rainfall event, with loss of more than 20% nitrate in the fields with conventional drainage. Stable isotope studies of N and O in the form of nitrate ion suggested that the decline of nitrate is caused by denitrification. Additionally, dissolved organic N (DON) was found in the drainage water, and the DON concentration was up to 70% of nitrate. Water-extractable N in the topsoil was primarily in the organic form and represented up to 30% of the available N.
From these results, we concluded that the nitrate loss by denitrification and discharge as DON seemed to affect the soil nitrogen fertility in the clayey ex-paddy fields.

Report

(4 results)
  • 2016 Annual Research Report   Final Research Report ( PDF )
  • 2015 Research-status Report
  • 2014 Research-status Report
  • Research Products

    (3 results)

All 2017 2016 2014

All Presentation (3 results)

  • [Presentation] 粘土質転換畑での降雨流出過程における硝酸イオンNO同位体分別係数比2017

    • Author(s)
      鈴木 克拓、中島 泰弘
    • Organizer
      日本土壌肥料学会2017年度仙台大会
    • Place of Presentation
      東北大学青葉山新キャンパス(宮城県仙台市)
    • Year and Date
      2017-09-05
    • Related Report
      2016 Annual Research Report
  • [Presentation] 粘土質転換畑に特有な窒素の流出 - 脱窒による消失と溶存有機態での流出2016

    • Author(s)
      鈴木 克拓、中島 泰弘
    • Organizer
      日本土壌肥料学会2016年度佐賀大会
    • Place of Presentation
      佐賀大学本庄キャンパス(佐賀県佐賀市)
    • Year and Date
      2016-09-20
    • Related Report
      2016 Annual Research Report
  • [Presentation] 粘土質転換畑における降雨時の急激な脱窒 -硝酸イオンの窒素・酸素安定同位体比による検討-2014

    • Author(s)
      鈴木 克拓、中島 泰弘
    • Organizer
      日本土壌肥料学会2014年度東京大会
    • Place of Presentation
      東京農工大学小金井キャンパス(東京都小金井市)
    • Year and Date
      2014-09-09 – 2014-09-11
    • Related Report
      2014 Research-status Report

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Published: 2014-04-04   Modified: 2018-03-22  

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