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‘A’ Values of Potassium Related to Other Indexes of Soil Potassium Availability
Author(s) -
Nuttall W. F.,
Warkentin B. P.,
Carter A. L.
Publication year - 1967
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1967.03615995003100030018x
Subject(s) - avena , potassium , tracer , soil water , chemistry , fertilizer , radionuclide , isotope , greenhouse , liquid scintillation counting , potash , seeding , soil test , agronomy , radiochemistry , zoology , horticulture , environmental science , soil science , biology , physics , organic chemistry , quantum mechanics , nuclear physics
Abstract A technique was developed to measure ‘A’ values of K with oat ( Avena sativa ) plants grown in the greenhouse and with the radioactive isotope 42 K. The isotope 42 K has a short half‐life (12.42 ± .03 hours) and was applied to the soil as KCl (approximately 2 mc of 42 K/g of 39 K) 14 to 18 days after seeding. Plants were harvested to determine initial quantities of K at the time of tagged fertilizer application. Six days later the fertilized plants were harvested and the activity in the plant tissue was counted in a liquid scintillation spectrometer. For 11 soils the total of exchangeable K plus nonexchangeable K accounted for 56% of the variability in K uptake at the time of tracer application, whereas 92% of the variability in ‘A’ values was accounted for by these measurements. Results from the experiments indicated that both amounts of exchangeable and nonexchangable K should be used as availability indexes.