Ext. of microalgae, emulsifier and mixts. thereof prepd. in ratio of 1:1, 1:10, 1:100 and 1:100 were added to soil samples used for cultivation of rapeseed and mustard. The effects were assessed after 3 and 6 days by detn. the amts. of germinated plants and the length of their roots. The best stimulation of plant growth was achieved at 1:1 and 1:100 in both cases. Addnl., biostimulant toxicity for Eisenia fetida earthworms was assessed. The biostimulant was added to the soil sample with a predetd. no. of earthworms. After 14 day test, no difference in body mass changes of the earthworms and their mortality were obsd.