Effects of extraction time and phosphorus speciation on soil test phosphorus data: A case study of Illinois agricultural soils

Anthony P. Miller, Yuji Arai

Research output: Contribution to journalArticlepeer-review

Abstract

Bray P-1 and Mehlich III STP extractions aim to assess the concentrations of labile P in soils. It is unknown, however, how the observed quantity of labile P is affected by the release of variable P species. The kinetics of orthophosphate (Pi), organic-P (Po), and colloidal P were evaluated in manure-amended and chemical fertilizer-amended Central Illinois agricultural soils using Bray-1 and Mehlich III extractants. In both soils, Bray and Mehlich III extractable P increased with increasing time. The extracted P species are not only Pi but also Po and colloidal P. Between 10 and 15% of total Po was extracted from each soil with manure amended soils releasing more total Po than fertilizer amended soils. BrayP-1 and Mehlich III extracted colloidal P from manure-amended and fertilizer-amended soils, but concentrations were only significant after 1–3 h. The results indicate that P speciation and extraction time have major impacts on the results of STP extractions, therefore, to fertilizer recommendation.

Original languageEnglish (US)
Pages (from-to)62-69
Number of pages8
JournalGeoderma
Volume305
DOIs
StatePublished - Nov 1 2017

Keywords

  • Bray
  • Mehlich III
  • Phosphorus
  • Soil test phosphorus
  • Speciation
  • Time

ASJC Scopus subject areas

  • Soil Science

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