KCl Extractable Aluminum

Reagents
Potassium chloride (KCl)

Preparation of Reagents
1.0N KCl: Dissolve 74.56g KCl per liter in deionized water and make to volume.

Sample Preparations and Procedure
Weigh, in duplicate, 10g soil into 125mL Erlenmeyer flasks. Include blanks. Add 50mL 1.0N KCl to each, swirl gently to thoroughly wet, cover and allow to stand overnight.

Attach appropriately numbered 125mL Erlenmeyer flasks equipped with Buchner funnels and Whatman No. 42 filter paper to vacuum manifold. Moisten filter paper and turn on vacuum to seal it. Swirl sample vigorously and pour into filter funnels using the vacuum to avoid dislodging the filter paper. Using vacuum as necessary, sequentially leach five 10mL aliquots of KCl through each sample and blanks.

Swirl each filter flask to mix and transfer about 30 mL to numbered plastic bottles. Refrigerate. Discard the remaining sample.

Sample Calculations
Meq/100g = ((sample ppm * sample dilution factor)-(blank ppm * Blank dilution factor)) *elemental constant

Elemental constant for Aluminum = 1/89.9 = 0.01112.

References
Soil Survey Laboratory Methods Manual. August 1992.  p.193.  U.S. Department of Agriculture.