Self-sustaining nitrogen supply system in long-term unfertilized paddy-field

Research Project

Project/Area Number	24658014
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Single-year Grants
Research Field	Crop science/Weed science
Research Institution	Hirosaki University
Principal Investigator	SUGIYAMA Shuichi 弘前大学, 農学生命科学部, 教授 (00154500)
Project Period (FY)	2012-04-01 – 2014-03-31
Project Status	Completed (Fiscal Year 2013)
Budget Amount *help	¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000) Fiscal Year 2013: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000) Fiscal Year 2012: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Keywords	イネ / 有機栽培 / 施肥 / 窒素収支 / 収量 / 水稲 / 無肥料 / 土壌微生物 / 水稲栽培 / 有機農業 / 窒素肥料
Research Abstract	Fertilization including both chemical and organic forms is essential for sustainable crop production. However, several paddy field farmers in Japan successfully attain high yield without any fertilization for more than 30 years. To clarify this mechanism, six paddy rice fields in Tohoku region were compared in terms of nitrogen balance. Tillering activity during vegetative growth stage was a key component in regulating rice field. High-yield paddy fields had higher ability to supply mineralized nitrogen resulting from high soil decomposing activity than low-yield fields.