
%0 Journal Article
%A Poile, GJ 
%A Ring, SM 
%A Conyers, MK 
%A Slattery, WJ 
%T The influence of centrifuging on phosphorus (Olsen P) soil test values
%J Soil Research
%D 1990/08/01
%V 28
%N 4
%P 559-562
%K 
%R https://doi.org/10.1071/SR9900559
%U https://www.publish.csiro.au/paper/SR9900559 
%X Variation in soil Olsen P tests can arise from the method of separation of the solution extract from the soil. With increasing centrifugation of the NaHC03 extract solution, we observed a decline in solution P values and these approached the P values obtained on soil-filtered extracts. The decline in solution P with increasing centrifugation was associated with a decline in organic carbon in the NaHC03 solution. We caution against unpublished modifications to methods and recommend that for consistency, simplicity, speed and cheapness, the NaHCO3 extract be soil-filtered as in the original method. 
