1. Select GREENHOUSE from the OPERATION MENU.
2. Use SOL1 and SOL3 instrument calibration standards from the soil analysis section EXTRACTABLE P, K, Ca, Mg, Zn, Mn - ICP METHOD, pages 12 and 13, to standardize the instrument.
3. Report results as ppm.

SOLUBLE NH₄-N (COLORIMETRIC - AUTOANALYZER METHOD)

1. Proceed as in the soil analysis section, EXTRACTABLE NH₄-N, page 27, using the same instrument calibration standards, with the following exceptions:
   1. STANDARDS, step 2 - Instrument readout values will be equal to the final concentration values.
   2. PROCEDURE, step 5 - select NH₄GH from the sample table menu.
   3. PROCEDURE, step 10 - select NH₄GH from the collect data menu.
   4. Report results as ppm.

SOLUBLE NO₃-N (COLORIMETRIC - AUTOANALYZER METHOD)

1. Proceed as in the soil analysis section EXTRACTABLE NO₃-N, page 32, using the same instrument calibration standards, with the following exceptions:
   1. STANDARDS, step 2 - Instrument readout values will be equal to the final concentration values.
   2. PROCEDURE, step 5 - select NO₃GH from the sample menu table.
   3. PROCEDURE, step 10 - select NO₃GH from the data collect menu.
   4. Report the results as ppm.

REFERENCE

1. Warncke, D. D., 1986, Analyzing greenhouse growth media by the saturationextraction method. Hort. Sci. 21:223-225.