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Re: [SANET-MG] CO2 Extraction - Soil Testing

Hey Joel -

I looked into the Morgan soil test several years back and
went to the library to see the original agricultural experiment
station bulletins, as below.

It was an early soil test extract solution that resulted in a quick
test with color-coded results.  The bulletins have the original
color plates.  The LaMotte Soil Test Kit was based on the
Morgan Universal Soil Extract and they still sell soil test kits
to farmers as well as professional labs.

I think that Carey Reams adopted the Morgan soil test for
this reason.  He was a farm advisor who taught farmers how
to do their own quick tests and make adjustments during
the growing season, using soil and foliar amendments.   He also
likened the weak acetic acid buffer for available plant nutrients
to be be similar to organic acids from root exudates and
so forth.

As you know, the modern labs have a long list of specific
soil extracts for regional soil conditions and elemental analysis,
including Morgan, Modified Morgan, Mehlich, Olsen, etc.
Colorimeters and spectrophotometers provide detailed and
accurate results.

Morgan, M. F. 1939. The Universal Soil Testing System. Connecticut
Agr. Expt. Sta. Bull. 392.

Morgan, M.F. 1941. Chemical Soil Diagnosis by the Universal Soil
Testing System. Connecticut Agric. Exp. Sta. Bull. 450.

Lunt, H.A., C.L.W. Swanson, and H.G.M. Jacobson. 1950.
The Morgan Soil Testing System.  Connecticut Agric. Exp. Sta.
Bull. 541.

Interestingly, the eco-farming system still follows the advanced
methods that Carey Reams advocated.  In addition to soil
monitoring, they have adopted the three-pocket meter approach
to tissue sap monitoring, using the Brix, pH, and EC meters.

Perhaps you would like to check in with ATTRA and get
the resource list titled "An Eco-Farming Approach to Foliar
Fertilization," available in print only.

Steve Diver

Is any one familiar with the history of the Morgan extractant ?


Joel Gruver
Dept of Soil Science
NC State University

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