CCMP: Alkaline Soil Extract

(Provasoli et al. 1957)

Combine two parts dH₂O with one part rich organic garden soil (containing no recent applications of chemical fertilizer or pesticides). Add 2-3 g NaOH/liter. Autoclave for 2 hours, cool and filter. This concentrated extract is then diluted 50:1 with dH₂O to make the final working stock.