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A Reevaluation of Phosphorus‐32 and Resin Methods in a Calcareous Soil
Author(s) -
Bowman R. A.,
Olsen S. R.
Publication year - 1979
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/sssaj1979.03615995004300010022x
Subject(s) - calcareous , chemistry , phosphorus , soil water , soil test , wetting , soil science , geology , materials science , paleontology , organic chemistry , composite material
Four experiments were run to evaluate the resin and 32 P methods as valid laboratory methods in a calcareous soil. Recovery of four levels of added KH 2 PO 4 , after several cycles of wetting, drying, and mixing was evaluated. Total‐exchangeable P (TEP 24 ) was determined by the carrier‐free method, and resinextractable P by equilibrating 1 g soil sample with 2 g resin overnight. Equilibrium of 31 P and 32 P on the soil‐solid phase was evaluated by measuring specific activities with time. Different soil‐solution ratios, using water and 0.01 M CaCl 2 as extractants, were evaluated to determine their effects on the total exchangeable P. Water and four different salts at three different molarities were used as extractants with 1 and 2 g resin to determine total released P in solution and on the resin. The recovery experiment showed a high correlation between added and recovered P, using both TEP 24 and resin methods; the time‐equilibration study indicated a lack of complete equilibrium between 31 P and 32 P after 2 hours shaking, and a near complete or complete equilibrium at 24 hours; different soil‐solution ratios did not affect total exchangeable P, and water extracted the most resin‐P and 0.01 M CaSO 4 the least (roughly one‐half of pure water):