Analytical Method: Nitrogen (total) in soils

Instruments and Reagents:

Cat.No. 173016  Spectroquant® VIS Spectrophotometer Prove 100 or

Cat.No. 173017  Spectroquant® UV/VIS Spectrophotometer Prove 300 or

Cat.No. 173018  Spectroquant® UV/VIS Spectrophotometer Prove 600 or

Cat.No. 109748  Spectroquant® Photometer NOVA 30 or

Cat.No. 109751  Spectroquant® Photometer NOVA 60 or

Cat.No. 173632  Spectroquant® Colorimeter Move 100

Cat.No. 114946  Rectangular cells 10 mm and/or

Cat.No. 114947  Rectangular cells 20 mm and/or

Cat.No. 114944  Rectangular cells 50 mm
Cat.No. 114537  Spectroquant® Nitrogen Cell Test
Cat.No. 100613  Spectroquant® Nitrogen Cell Test*
Cat.No. 114763  Spectroquant® Nitrogen Cell Test*
Cat.No. 102382  Calcium chloride dihydrate for analysis
Cat.No. 116754  Water for analysis
Charcoal activated for soil tests
*not compatible with Move 100
Calcium chloride solution 0.025 mol/l:
Dissolve 3.68 g calcium chloride dihydrate with 1 l of water for analysis.

Sample preparation:
In a glass bottle mix 50 g of naturally moist sample, free from coarse stones, with 100 ml of a calcium chloride solution 0.025 mol/l. Add a spatula-tipfull of charcoal activated for soil tests and shake the closed bottle in a shaking machine for 1 hour (alternative stir in a beaker). Let the suspension settle and filter it through a folded filter.
For determination of the water-content dry a similar sample to constant weight in the drying kiln at 105 °C. A drying of the sample before determination is not advisable because of the fast change in the nitrogen-forms. The analysis should take place very quickly. Storing the sample in plastic bags at room temperature changes the analysis values after a short time already.
Determine with the above mentioned test kits.
Nitrogen (total) content in mg/kg N = analysis value in mg/l N x 2


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