ISSN: 0041-3216 (Online), 0041-3216 (Print)
Volume 70 Number 1
Comparison of extractants for determination of available P, K, and Ca in some Grenada soils
The Bray Pl extractant for estimation of available P and 1N NH4OAC (pH 7 .0) solution for estimation of exchangeable K and Ca have been adopted for routine analysis of Grenada soils by the Grenada Soil Testing Laboratory. The multi-element extractants, Mehlich 1 and Mehlich 3 solutions, were compared with these standard soil test extractants for available P and exchangeable K and Ca on nine Grenada soils. All the relationships were significant. For available P the best relationship was between the Mehlich 3 and Bray Pl extractants (r2 = 0.88). The relationship between the Mehlich extractants and Bray Pl was improved when the cultivated form of the Capitol clay loam was excluded. The best relationship for exchangeable K was between the Mehlich 1 and the NH4OAC extractants (r2 = 0.96); for exchangeable Ca, it was between the NH4OAC and the Mehlich 3 (r2 = 0.97). These results show that either the Mehlich 1 or Mehlich 3 extractants can be used instead of the standard methods for routine analysis for P, K, and Ca in these soils.
Keywords: Grenada soils; Soil testing; Extractable nutrients; Soil extractants