Saturated Extract (SE)

Samples should be logged in the log book.


  1. Fill 600 mL plastic beakers with sample mix. Bring to field capacity with distilled water, stirring gently to avoid breaking encapsulated fertilizer pellets and allow to equilibrate for 1 h.
    1. Note: At saturation, the sample will flow slightly when tipped andcan be easily stirredwith a spatula. The saturated sample should have no appreciable wateron the surface,nor should it have stiffened. If additional water needs to be added,allow to equilibrate an additional 1/2 h.
  2. Vacuum filter through # 4 filter paper and collect at least 110 mL of the extract.
  3. Pour an aliquot into a test tube to determine extractable P, K, Ca, and Mg routinely in the laboratory, using the ICP.
  4. Save 100 mL to use for the rest of the analyses.
  5. Determine soluble salt content on the solubridge and convert to mmhos/cm by moving decimal three (3) places to the left. Record value with 2 decimal places.
    1. (See Plant and Feed Manual for meter instructions.)
  6. Determine soil pH by glass electrode in a separate subsample by routine lab procedure.
  7. Determine NO3-N by FIAlab nitrate analyzer.
  8. Saturated extract results are reported on the Special Analyses Report sheet. Lab number should be the log book number for that sample as recorded. Method of extraction is SE. Nutrient analyses should be reported in ppm. These values may be calculated by dividing soil test lb/A values by 8 (now done automatically by the computer). NO3-N values do not require calculation.