Comparing phosphorus indices from twelve southern U.S. states against monitored phosphorus loads from six prior southern studies

D. Osmond, A. Sharpley, C. Bolster, M. Cabrera, S. Feagley, B. Lee, C. Mitchell, R. Mylavarapu, L. Oldham, F. Walker, H. Zhang

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

Forty-eight states in the United States use phosphorus (P) indices to meet the requirements of their Natural Resources Conservation Service (NRCS) Code 590 Standard, which provides national guidance for nutrient management of agricultural lands. The majority of states developed these indices without consultation or coordination with neighboring states to meet specific local conditions and policy needs. Using water quality and land treatment data from six previously published articles, we compared P loads with P-Index values and ratings using the 12 southern P indices. When total measured P loads were regressed with P-Index rating values, moderateto very strong relationships (0.50 to 0.97) existed for five indices (Arkansas, Florida, Georgia, North Carolina, and South Carolina) and all but one index was directionally correct. Regressions with dissolved P were also moderate to very strong (r2 of 0.55 to 0.95) for the same five state P indices (Arkansas, Florida, Georgia, North Carolina, and South Carolina); directionality of the Alabama Index was negative. When total measured P loads were transformed to current NRCS 590 Standard ratings (Low [<2.2 kg P ha-1], Moderate, [2.2-5.5 kg P ha-1], and High [>5.5 kg P ha-1]) and these ratings were then compared to the southern-Index ratings, many of the Pindices correctly identified Low losses (77%), but most did not correctly identify Moderate or High loss situations (14 and 31%, respectively). Th is study demonstrates that while many of the P indices were directionally correct relative to the measured water quality data, there is a large variability among southern P indices that may result in different P management strategies being employed under similar conditions.

Original languageEnglish
Pages (from-to)1741-1749
Number of pages9
JournalJournal of Environmental Quality
Volume41
Issue number6
DOIs
StatePublished - Nov 2012

ASJC Scopus subject areas

  • Environmental Engineering
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution
  • Management, Monitoring, Policy and Law

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