| Project/Area Number |
26450083
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Multi-year Fund |
|---|
| Section | 一般 |
|---|
| Research Field |
Plant nutrition/Soil science
|
|---|
| Research Institution | National 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.
|
