Abstract

The relative contribution of phosphorus (P) from agricultural nonpoint sources to surface water quality problems has increased in recent years as point sources of P have been reduced significantly. Phosphorus contributes to eutrophication, which restricts water use for fisheries, recreation, industry, and human consumption due to increased growth of undesirable algae and aquatic weeds, followed by oxygen shortages as the
biomass decomposes. The increased attention on P has increased the demand for information on methods of analysis for soil, water, and residual materials for environmentally relevant forms of P. The purpose of this publication is to present these methods in a single document. Previously, the methods have appeared across a wide variety of documents or only in the scientific literature. It is not the intent of this publication to define a uniform set of recommended methods for agronomic soils tests, water, or residual materials. The methods presented here are intended solely to provide a set of uniform testing methods for environmental scientists working across an enormous range of soil and climatic conditions, with the hope that comparable methods may lead to improved communication and understanding of this complex issue.

FOREWARD

As scientists focus on the fate of phosphorus applied to agricultural lands, it has become increasingly clear that a standard set of soil testing methods is needed to enable uniform comparison of results across county, state, regional, and even national boundaries.

By contrast, soil testing developed with a high priority on meeting local needs. As a result, many local variations in extractants and laboratory procedures have been made to achieve timely analysis and improved correlation of soil test results with plant responses within well-defined regions. Over time, enormous amounts of information on individual soils, crops and extractants have been developed using these localized modifications and laboratory methods. Soil testing labs cannot easily change from one extractant to another. The cost of repeating these calibration experiments for many soils and crops is prohibitively expensive, and the changes would initially preclude users from comparing
results across years. Even so, a set of standard reference methods can be useful for laboratories wishing to consider a new analysis for a particular element, and for comparing results across laboratories. In 1992, SERA-IEG-6 selected 15 reference procedures for soil testing laboratories in the southern region. Criteria for selection included the accuracy of the method in predicting crop responses, and general
acceptability by workers in the soil testing field.

This publication in no way attempts to define a uniform set of recommended methods for agronomic soil tests. The methods presented here are intended solely to provide a set of uniform testing methods for environmental scientists working across an enormous range of soil and climatic conditions, with the hope that comparable methods may lead to improved communication and understanding of this complex issue.

For more information on agronomic soil testing methods, and the source of many of the procedures described here, the reader should refer to the recent bulletins compiled by the various regional committees working on nutrient analysis of soils, plants, water, and waste materials (SERA-IEG-6, NRC-13 and NEC-67).

TABLE OF CONTENTS

Methods of Phosphorus Analysis for Soils, Sediments, Residuals, and Waters: Introduction.........1
Gary M. Pierzynski, Kansas State University
A.N. Sharpley, USDA-ARS, University Park, PA
Soil Test Phosphorus: Principles and Overview........................................5
J. Thomas Sims, University of Delaware
Sample Collection, Handling, Preparation, and Storage........................ 10
Frank J. Coale, University of Maryland
Soil Test Phosphorus: Bray and Kurtz P-1............................................ 13
J. Thomas Sims, University of Delaware
Soil Test Phosphorus: Mehlich 1.............................................................. 15
J. Thomas Sims, University of Delaware
Soil Test Phosphorus: Mehlich 3.............................................................. 17
J. Thomas Sims, University of Delaware
Soil Test Phosphorus: Olsen P.................................................................. 20
J. Thomas Sims, University of Delaware
A Phosphorus Sorption Index ................................................................... 22
J. Thomas Sims, University of Delaware
Determination of Water- and/or Dilute Salt-Extractable Phosphorus . 24
M.L. Self-Davis, University of Arkansas／P.A. Moore, Jr., USDA-ARS, Fayetteville, AR／B.C. Joern, Purdue University
Phosphorus Extraction with Iron Oxide-Impregnated Filter Paper (Pi test)................................................................... 27
W.J. Chardon, DLO Research Institute for Agrobiology and Soil Fertility, The Netherlands
Determination of the Degree of Phosphate Saturation In Non-Calcareous Soils ..................................................... 31
O.F. Schoumans, Winand Staring Centre for Integrated Land, Soil and Water Research, The Netherlands
Phosphorus Sorption Isotherm Determination ....................................... 35
D.A. Graetz, University of Florida／V.D. Nair, University of Florida
Bioavailable Phosphorus in Soil ................................................................ 39
Andrew Sharpley, USDA-ARS, University Park, PA
Total Phosphorous in Soil .......................................................................... 45
M.R. Bender and C.W. Wood, Auburn University
Phosphorus Fractionation.......................................................................... 50
Hailin Zhang, Oklahoma State University／John L. Kovar, USDA/ARS, Ames, IA
Phosphorus Fractionation in Flooded Soils and Sediments ................... 60
Philip Moore, USDA-ARS, Fayetteville, AR／Frank Coale, University of Maryland
Determination of Phosphorus Retention and Flux in Soil...................... 65
Thanh H. Dao, USDA-ARS
Sampling Techniques for Nutrient Analysis of Animal Manures.......... 71
D.A. Crouse, S.C. Hodges, C.R. Campbell, J.P. Zublena, North Carolina State University
Determining Water Soluble Phosphorus in Animal Manure................. 74
M.L. Self-Davis, University of Arkansas／P.A. Moore, Jr., USDA-ARS, Fayetteville, AR
Total Phosphorous in Residual Materials ................................................ 77
M.R. Bender and C.W. Wood, Auburn University
Sample Collection, Handling, Preparation and Storage......................... 84
P.M. Haygarth, Institute of Grassland and Environmental Research, England／A.C. Edwards, Macaulay Land Use Research Institute, Scotland
Analyzing for Dissolved Reactive Phosphorus in Water Samples......... 91
D.H. Pote, USDA-ARS, Booneville, AR／T.C. Daniel, University of Arkansas
Analyzing for Total Phosphorus and Total Dissolved Phosphorus in Water Samples ............................................. 94
D.H. Pote, USDA-ARS, Booneville, AR／T.C. Daniel, University of Arkansas
Using the Iron Oxide Method to Estimate Bioavailable Phosphorus in Runoff ............................................................. 98
R.G. Myers, Kansas State University／G.M. Pierzynski, Kansas State University