Wei Zhang - Evaluation of Two Langmuir Models for Phosphorus Sorption of Phosphorus-Enriched Soils in New York for Environmental Applications

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  Publication Details (including relevant citation   information): Zhang, Wei, Faulkner, Joshua W., Giri,   Shree K., Geohring, Larry D., Steenhuis, Tammo S.,   2009, 174 (10)

  Abstract: The phosphorus (P) sorption isotherm   experiment is a widely used tool in environmental applications   for assessing soil's vulnerability to P loss to runoff or   drainage. The sorbed legacy P (S0) (i.e., the P retained in soils   from previous P applications) participates in sorption processes   but cannot readily be determined in a sorption experiment. Thus,   it is important to accurately estimate S0 for P-enriched soils   (e.g., the soils that heavily receive fertilizer, manure, farm   wastewater, or sewage sludge). Two curve-fitting procedures   (i.e., one-step method and two-step method) with Langmuir models   have been used to estimate S0 and other sorption parameters,   including the P sorption maxima (Smax), the bonding energy   constant (k), and the zero-sorption equilibrium concentration   (EPC0). This study evaluated these two methods on 16 samples of   Langford, Volusia, and Mardin channery silt loam soils at surface   (0-8 cm) and subsurface (61-91 cm) in New York. The results   indicate that the two methods agreed well in estimating P   sorption maxima, and the estimates of k were close. The S0   estimates by the two methods had a good agreement for surface   soils but a poor agreement for subsurface soils, which may be of   little concern because of small S0 of subsurface soils. Although   the one-step method yielded greater EPC0 estimates, the EPC0   estimates by the two methods had an excellent linear correlation   for P-enriched surface soils, suggesting that both methods could   work equally if only the relative magnitudes of EPC0 among soils   are needed. Overall, both methods are acceptable to fit the   Langmuir isotherms.

  Address (URL): http://journals.lww.com/soilsci/Fulltext/2009/10000/Evaluation_of_Two_Langmuir_M odels_for_Phosphorus.1.aspx