Development of field methods for evaluating acquisition of potassium by rice plants

Research Project

Project/Area Number	25870340
Research Category	Grant-in-Aid for Young Scientists (B)
Allocation Type	Multi-year Fund
Research Field	Plant nutrition/Soil science Environmental agriculture(including landscape science)
Research Institution	Kyoto University
Principal Investigator	MORITSUKA Naoki 京都大学, (連合)農学研究科(研究院), 助教 (10554975)
Project Period (FY)	2013-04-01 – 2015-03-31
Project Status	Completed (Fiscal Year 2014)
Budget Amount *help	¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000) Fiscal Year 2014: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000) Fiscal Year 2013: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Keywords	水田土壌 / カリウム / 根域 / 空間変動 / 固定容量 / 空間変動解析 / 根域土壌 / 局所施肥 / 水田 / 非交換態 / 局所施用
Outline of Final Research Achievements	Experiments were attempted to find how rice plants acquire potassium (K) in a paddy field. I obtained the following results. 1) In a field experiment where planted and unplanted plots were equipped, it was found that exchangeable K in soil decreased from planting to full heading stages and increased thereafter. 2) At a greater scale covering five paddy fields, only a weak relationship was found between exchangeable K and boiling HNO3-extractable nonexchangeable K. The former and the latter fractions were regulated by organic matter and clay contents, respectively. 3) The K-fixation capacity was quantified by saturating a soil sample with KCl, which was followed by repeated extraction of fixed K with NH4OAc and HCl. The K-fixing capacity thus evaluated was found to increase, when the soil was located around plant roots or it was subjected to flooding.