The effects of soybean cultivation as one of rotation crops on the capacity of soil inorganic nitrogen supply

Research Project

Project/Area Number	24580019
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Research Field	Crop science/Weed science
Research Institution	The University of Tokyo
Principal Investigator	YAMAGISHI Junko 東京大学, 農学生命科学研究科, 准教授 (60191219)
Co-Investigator(Kenkyū-buntansha)	OKADA Kensuke 東京大学, 大学院農学生命科学研究科, 教授 (80391431)
Project Period (FY)	2012-04-01 – 2015-03-31
Project Status	Completed (Fiscal Year 2014)
Budget Amount *help	¥5,590,000 (Direct Cost: ¥4,300,000、Indirect Cost: ¥1,290,000) Fiscal Year 2014: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000) Fiscal Year 2013: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000) Fiscal Year 2012: ¥2,730,000 (Direct Cost: ¥2,100,000、Indirect Cost: ¥630,000)
Keywords	環境調和型農業 / 作付体系 / 無機化 / 無機態窒素 / 団粒構造 / 土壌肥沃度 / 食用作物 / ダイズ / 団粒 / 土壌微生物
Outline of Final Research Achievements	The cultivation of soybean was known to promote the growth of succeeded crops, though soybean absorbed so much nitrogen from soil with assimilated nitrogen by nodules. We examined the effects of soybean (nodulated and non-nodulated soybean) cultivation on soil properties. As results, inorganic nitrogen content in soil, soil aggregation destruction and soil respiration were highest under nodulated soybean cultivation, followed by non-nodulated soybean and then corn cultivation. The growth of barley was also better after soybean cultivation than corn cultivation, because barley could absorb more nitrogen. Therefore, we concluded that soybean produced inorganic nitrogen by reduction of soil aggregation and increase of microorganisms’ biomass.