(Modified) Morgan soil test method To determine the Cornell Morgan soil test Pof a soil, the
soil is shaken (extracted) with a chemical solution (sodiumacetate buffered at pH 4.8)
in a particular soil to extraction solution ratio (1:5) and for a certain amount of time (15 minutes). The extract is filtered (Figure 1) and the P concentration in the filtered
extract is measured in the laboratory (colorimetrically).
Cornell University is not the only university that uses the Morgan soil test.
This same test is the basis for fertility guidelines ofthe University of Massachusetts
and a similar chemical extraction solution (ammoniumacetate instead of sodiumacetatecalled the Modified Morgan extraction) is used for fertility guidelines at the Universities o