The principle, equipment, reagents, standards, autoanalyzer solutions, procedure, and quality control are the same as those specified in the soil analysis method for extractable NH₄-N pages 27-31 (or go here), with the following exceptions.

1. Standards - step 2 - the instrument readout column is changed to be identical with the final concentration column. The concentration in the instrument readout column is changed to ppm.
2. Procedure - step 5 - changed to: Select NH4WATR from the sample table menu.
3. Procedure - step 10 - changed to: Select NH4WATR from the collect data menu.