Form and Availability of P in Selected Virginia Soils as Related to Available P Tests1
- D. C. Martens,
- J. A. Lutz and
- G. D. Jones2
Relationships among inorganic P fractions, P extracted by the acid fluoride (Bray no. 1), and dilute acid (Mehlich) soil tests, and the P supplying power of Davidson clay loam, Groseclose and Nason silt loams, and Wellston fine sandy loam were evaluated by correlation and regression analyses. The soils under study contained wide ranges in contents of inorganic P fractions and of P extracted by the soil tests due to application of various alnounts of different P sources during long-term field investigations. Correlation analyses indicated that P from the A1 phosphate fraction was the main source of P to oat plants (Arena saliva L. ‘Andrew’) grown in the greenhouse on the four soils.
Statistical data showed that P from the AI phosphate fraction was the predominant source of P extracted from each of the four soils by the acid fluoride soil test. Similar data indicated that the dilute acid soil test extracted P from mainly Ca phosphate in the Nason and Wellston soils and from A1 phosphate in the Groseclose soil. The close relationship between dilute acid extractable P and Ca phosphate in the Nason silt loam and Wellston fine sandy loam was explained as extraction of P from rock phosphate which had been applied to the soils during long-term field investigations. Phosphorus extracted by the dilute acid soil test was not closely related to any of the inorganic P fractions in the Davidson clay loam.
Acid fluoride extractable P was more closely related than dilute acid extractable P to P uptake from each soil, except the Groseclose silt loam. Phosphorus extracted by both soil tests was equally related to P uptake from the Groseclose soil. The acid fluoride extractable P contents required to attain maximum yield was inversely related to the clay contents of the Davidson, Groseclose, and Wellston soils.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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