Journal of
Soil Science and Environmental Management

  • Abbreviation: J. Soil Sci. Environ. Manage.
  • Language: English
  • ISSN: 2141-2391
  • DOI: 10.5897/JSSEM
  • Start Year: 2010
  • Published Articles: 287

Full Length Research Paper

Re-defining and quantifying inorganic phosphate pools in the soil and water assessment tool

Richard L. Haney
  • Richard L. Haney
  • USDA-ARS, Grassland, Soil and Water Research Laboratory, 808 East Blackland Road, Temple, TX 76502, USA.
  • Google Scholar
Michael J. White
  • Michael J. White
  • USDA-ARS, Grassland, Soil and Water Research Laboratory, 808 East Blackland Road, Temple, TX 76502, USA.
  • Google Scholar
Jeffrey G. Arnold
  • Jeffrey G. Arnold
  • USDA-ARS, Grassland, Soil and Water Research Laboratory, 808 East Blackland Road, Temple, TX 76502, USA.
  • Google Scholar
Elizabeth B. Haney
  • Elizabeth B. Haney
  • Texas A&M University, Texas AgriLife Research and Extension Center, 720 E. Blackland Road, Temple, TX 76502, USA.
  • Google Scholar
R. Daren Harmel
  • R. Daren Harmel
  • Texas A&M University, Texas AgriLife Research and Extension Center, 720 E. Blackland Road, Temple, TX 76502, USA.
  • Google Scholar


  •  Accepted: 19 December 2013
  •  Published: 31 December 2013

Abstract

The soil and water assessment tool (SWAT), a large-scale hydrologic model, is used to estimate phosphate (P) loading in streams and water bodies. The labile, active, and stable P pools are currently used to represent P cycling in SWAT; however, these pools are conceptual without any chemical basis. The current structure allows SWAT to reasonably represent P cycling; however, restructuring and incorporation of recent research results should produce more accurate P simulations. This paper presents a redefined SWAT structure using four inorganic soil P pools (water soluble, labile, active, and stable) combined with soil extraction methods to determine initial values for each pool. The redefined structure was selected by examining the chemical characteristics of laboratory tests relative to soil P pools and analyzing the relationships between test results. Water soluble P, labile P and active P are determined using water, H3A, Mehlich 3 extraction, respectively. Stable P is determined with an acid digestion. Redefining SWAT’s inorganic soil P pools based on soil and extractant chemistry will improve the defensibility, credibility, and the accuracy of SWAT P routines in water resource planning, management, and decision making. 

Key words: Soil and water assessment tool (SWAT), phosphate, soil extractants, H3A, Olsen, Mehlich 3.
 
 

 

Abbreviation

SWAT, Soil and Water Assessment Tool; STP, soil test phosphorus; PAI, phosphorus availability index; NAPT, North American proficiency testing.