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Phosphorus Release Kinetics and Extractable Phosphorus after Long‐term Fertilization
Author(s) -
Steffens D.
Publication year - 1994
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/sssaj1994.03615995005800060018x
Subject(s) - chemistry , phosphorus , lime , soil water , alfisol , phosphate , zoology , kinetics , phosphorite , environmental chemistry , calcium , biochemistry , soil science , biology , geology , paleontology , physics , organic chemistry , quantum mechanics
If different P fertilizers have been applied for a long time, it is difficult to measure the P availability. The objectives of this study were to investigate (i) the kinetics of soil P release by electroultrafiltration (EUF), (ii) extractable P using different soil extractants, (iii) plant P uptake, and (iv) the importance of considering both the P release kinetics and extractable P for plant P uptake prediction. This study was conducted with 15 European Alfisol topsoils with different histories of P and lime applications. The soils had received P as basic slag phosphate (BSP), superphosphate (SP), partially acidulated phosphate rock (PAPR), and phosphate rock (PR) for a long period. Plant P availability was measured in a 4‐yr pot experiment with different plants. Phosphorus release kinetics analyzed by EUF were better described by the Elovich equation than by other diffusion functions. The Elovich b values, which can be used as an index of release rate, ranged from 53.5 to 140.0 mg P kg −1 soil min −1 . These b values were more closely correlated to cumulative plant P uptake ( r = 0.96) than P extracted with water ( r = 0.90), calcium acetate‐calcium lactate‐acetic acid (CAL) ( r = 0.89), Mehlich 3 ( r = 0.81), and double lactate ( r = 0.79). Only Elovich b values in the PAPR and PR treatments were significantly correlated to cumulative plant P uptake ( r = 0.92). The cumulative plant P uptake of the 15 soils was well predicted with the fitted equation: y = 27.8 + (0.40 CAL P) + (0.83 b ), r = 0.99, where y denotes the plant P uptake and b is the Elovich b value (mg P kg −1 soil min −1 ) and CAL P is the adsorbed P. This indicates that considering the b value as a parameter for P release and the amount of CAL‐extractable P for determining P availability following different fertilizer applications is a better estimation of plant P uptake than consideration of only one index of P availability.