e4cc7769_he_Merseyside_Skeptics_Society__Mode_of_application
[Biodynamic Preparations] 502 [Contents of the preparation] Flower heads of yarrow fermented in a stag’s bladder [Mode of application] 
Applied to compost along with preparations 503-507. Together these control the breakdown of the manures and compost, helping to make trace elements more available to the plant
Biodynamic Whine « The Merseyside Skeptics Society
Mode of application