Evaluation of availability of phosphorus reserved in Andisols for high yield of crop and savings of phosphorus resources.

Research Project

Project/Area Number	08660069
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	Plant nutrition/Soil science
Research Institution	Tohoku University
Principal Investigator	ITO Toyoaki Tohoku University, Experimental Farm, Faculty of Agriculture, Associate Professor, 農学部・附属農場, 助教授 (10176349)
Project Period (FY)	1996 – 1997
Project Status	Completed (Fiscal Year 1997)
Budget Amount *help	¥400,000 (Direct Cost: ¥400,000) Fiscal Year 1997: ¥400,000 (Direct Cost: ¥400,000)
Keywords	Colloidal composition / Allophanic Andisols / Nonallophanic Andisols / Total soluble inorganic phosphorus / EDTA-NaF extractable phosphorus / Anion exchange resin extractable phosphorus / pH / Al injury / 蓄積無機態リン / 可溶性蓄積リン / EDTA-NaF抽出リン / 陰イオン交換樹脂抽出リン / 高収量・省資源 / 土壌管理 / 蓄積土壌リン / 黒ボク土 / リン酸吸着活性 / リン可給性 / 根量
Research Abstract	Phosphorus (P) fertility of Andisols was evaluated with reference to colloidal composition of soils. P sorption capacity was strongly correlated to active aluminum (allophane and Al-humus complex). Nonallophanic Andisols with major active aluminum of Al-humus complex showed a higher P sorption capacity per active aluminum than allophanic Andisols with major active aluminum of allophane. Soil available P content decreased with increasing of P sorption capacity of soil. Total soluble inorganic P reserved in soil was extracted by EDTA-NaF solution. Plant absorbed greater amounts of P from allophanic Andisol than nonallophanic Andisol with equal level of total soluble P and available P (Truog and Bray methods). Nonallophanic Andisol needed more available P for good plant growth with compared to allophanic Andisol. Allophanic Andisol showed higher value of Truog-P and anion exchange resin extractable P than nonallophanic Andisol with equal amount of total soluble P.However, nonallophanic Andisol showed higher value of Bray-P and acetic acid extractable P than allophanic Andisol with equal amount of total soluble P.It was concluded that the accurate evaluation of P availability of Andisols must be conducted by extraction methods in consideration for soil colloidal composition. Plant available P decreased in nonallophanic Andisol with low pH less than 5.3.Soil available P contents did not change within the pH range of 4.5 to 7.0. In low pH,the inhibition of root elongation by Al injury caused the reduction in P absorption of plant.