Saturated Media Extract (SME)

The Saturated Media Extract is a water extract of the entire media sample. No attempt is made to sieve the sample before analysis. A representative sample of the media is wetted with deionized water until water just barely stands on the surface. The mixture is allowed to stand for 90 minutes and then filtered under suction. The filtrate is analyzed for important plant nutrients: nitrate and ammonia levels are determined by colorimetry, and phosphorus, potassium, calcium, magnesium, sodium, iron, manganese, zinc, copper, molydenum, and boron are all analyzed by ICP-AES. Results are reported as ppm (mg/L) in the media extract. The electrical conductivity is also determined on the above filtrate. The media pH is determined on a separte 5 cc subsample that is wetted with 5 mL of deionized water, allowed to stand for 15 minutes, and the pH determined using a pH meter with reference and glass electrodes.