Читать книгу Laboratory Methods for Soil Health Analysis, Volume 2 - Группа авторов - Страница 55

1 For soils that have a pH > 7.50

2 Test for the presence of inorganic carbon or carbonate (CaCO3) using concentrated H2SO4 or HCl.

3 Weigh 0.50 mg of the soil into a silver vessel and add 5 drops or (5 mL) of concentrated H2SO4 or HCl.

4 If effervescence is observed, inorganic carbon is present in the soil sample. If inorganic C is not present, go to Step 11.

5 Treat soil containing inorganic C with 0.1 mL of 4N phosphoric acid solution.

6 The treated sample should be allowed to dry for one or two days before analysis. Repeat steps for removal of inorganic C if necessary. Be cautious when handling the tins and do not use Al vessels as they will disintegrate when acid is added.

7 Weigh 50 mg of soil into an aluminum tin capsule using an analytical scale with 0.001 precision.

8 Fold the aluminum tin capsule containing the soil sample and load it on to the analyzer.

9 Weigh a known standard to serve as a check, using one standard every 12 to 20 samples. Standards can either be EDTA, aspartic acid, or soil with a known concentration of C.

* The operation of the analyzer should be operated according to the guidelines of the machine.