Module 3: Use of Conventional Techniques for Evaluating Phosphorus in Soils


Lecture 1: Isotherm determination

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Describes how isotherms are determined, explains some isotherm models, and gives details on sorption isotherm experiments to evaluate phosphorus sorption properties of soils and sediments. Provides additional details on equations for the Langmuir isotherm, the single point isotherm and the Freundlich isotherm.

  • References
    • Bache, B.W., and E.G. Williams. 1971. A phosphate sorption index for soils. J. Soil Sci. 22:289-301.
    • Graetz, D.A., and V.D. Nair. 2000.  Phosphorus sorption isotherm determination. In:  Pierzynski, G.M, editor, Methods of Phosphorus Analyses for Soils, Sediments, Residuals, and Waters. Southern Cooperative Series Bulletin No.396. SERA-IEG 17 Regional Publication.
    • Harris, W.G., R.D. Rhue, G. Kidder, R.B. Brown, and R. Littell. 1996. Soil Sci. Soc. Am. J. 60:1513-1521.
    • Reddy, K.R., G.A. O’Connor, and P.M. Gale. 1998. Phosphorus sorption capacities of wetland soils and stream sediments impacted by dairy effluent. J. Environ. Qual. 27:438-447
    • Nair, V.D., and K.R. Reddy. 2013.  Phosphorus sorption and desorption in wetland soils.  In: DeLaune, R., Reddy, K.R., Richardson, C.J., and Megonigal, P. (ed). Methods on biogeochemistry of wetlands. Soil Science Society of America Publication. (in press).
    • Reddy, K.R., M.R. Overcash, R. Khaleel, and P.W. Westerman. 1980. Phosphorus adsorption-desorption characteristics of two soils utilized for disposal of animal wastes. J. Environ. Qual. 9:86-92.Rhue, R.D., Harris, R.G., 1999. Phosphorus sorption/desorption reactions in soils and sediments. In: Reddy, K.R., O’Connor, G.A., Schleske, C.L. (Eds.), Phosphorus biogeochemistry in subtropical ecosystems. Lewis Publishers, Boca Raton, pp. 187–206.

    Additional References

    • Dari, B., V.D. Nair, and W.G. Harris. 2017. Approaches for evaluating subsurface phosphorus loss potential from soil profiles. Agric. Ecosyst. Environ. 245: 92-99.
    • Dari, B., V.D. Nair, and W.G. Harris. 2017. Parameters for Site-Specific Soil Phosphorus Loss Modeling from Soil Test Data. SL442. 
    • Dari, B., V.D. Nair, J. Colee, W.G. Harris, and R. Mylavarapu. 2015. Estimation of phosphorus isotherm parameters: a simple and cost-effective procedure. Front. Environ. Sci. 3:70. doi: 10.3389/fenvs.2015.00070.



Lecture 2: Applications of fractionation and isotherm parameters

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Describes phosphorus loss from a Spodosol, focusing on P extracted from high P-impacted soils, low P-impacted soils, and wetland and stream sediments. Discusses applications of isotherm parameters in particular environmental situations.



Lecture 3: P retention and release from biochar

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Defines biochar and describes its history and its use as a soil amendment. Discusses implications of biochar for phosphorus retention, and the soil properties that influence the effects of biochar application.



Lecture 4: The Phosphorus-Index (P-Index)

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Describes the P-Index, a site-specific tool for P risk assessment.



Lecture 5: The Quick P Field Test

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Explains the quick P field test, its advantages and uses, its methodology, its correspondence to Mehlich 1-P and water soluble P, and its detection limits.

Next - Module 4: Recent Developments in Techniques for Evaluating Phosphorus Release from Soils