Assessing Methods for Developing Phosphorus Desorption Isotherms from Soils using Anion Exchange Membranes |
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Authors: | S Sato N B Comerford |
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Institution: | (1) Department of Crop and Soil Sciences, Cornell University, Ithaca, NY 14853, USA;(2) Soil and Water Science Department, University of Florida, Box 110290, Gainesville, FL 32611, USA |
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Abstract: | Developing desorption isotherms for inorganic phosphorus (P) is a time-consuming and non-standardized procedure. Anion exchange
membranes (AEMs) have been successfully used in studies of P desorption kinetics and total membrane-desorbable P, but rarely
have they been used for developing P desorption isotherms. Our study had two objectives: (1) to evaluate the suitability of
using multiple strips of AEMs (termed the Multiple AEM Method) to develop P desorption isotherms; and (2) to compare the Multiple
AEM Method with a sequential-extraction approach using AEMs (termed the Sequential AEM Method) to determine if the manner
in which AEMs were used would influence the slope of the desorption isotherm, i.e. the partition coefficient. Both methods
yielded well-defined, but numerically different desorption isotherms for all levels of sorbed P. However, estimated K
d
values among methods were equivalent in the low and medium levels of P sorbed. The Multiple AEM method was quicker than the
Sequential AEM method, but both gave similar K
d
values in an agriculturally significant range of soil solution concentrations. These methods should be tested on a range
of soil type to determine their suitability in developing P desorption isotherms and to move toward method standardization
for desorption isotherms. |
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Keywords: | K d nutrient uptake modeling partition coefficient phosphorus bioavailability tropical soil |
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