Iris Publishers - World Journal of Agriculture and Soil Science (WJASS)
Trends in Soil Measurement Performance of
Australasian Laboratories by Methods and Time
This paper describes Australasian soil-measurement performance using
data from inter-laboratory soil proficiency programs
of the Australasian Soil and Plant Analysis Council Inc. Rapid
assessments focused only on grand median percent robust coefficients
of variation (%CVs) from 2004-05 through to 2014-15 inclusive, where
grand medians by method were calculated across 12 soil
samples annually. The %CV data were subdivided into three groupings
(2005-2008, 2009-2012, 2013-2015). For 19 soil tests, CVs
declined from 12.8% to 10.6% to 8.8%, suggestive of small improvements
in measurement quality with time. Detailed assessments
used data from 2009-10 to 2014-15 and included tests regulated for use
in “reef catchments” of North-east Australia. Relationships
between median-concentrations and associated robust %CVs were initially
assessed with power-functions, with each subsequently
solved for realistic analyte levels. Predicted trends for each method
for the six years were then plotted. From these, soil tests with
most variation were Total P, Bray-1P and Acid P.
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