Biodynamic field spray preparations 500, 500 & 508 | Term used collectively for those three (of nine) Biodynamic preparations which are sprayed directly on the vineyard (or farm), namely Horn manure 500, Horn silica 501, and Equisetum arvense 508 (Common horsetail). Of the other six, five (yarrow, chamomile, stinging nettle, oak bark, dandelion) are inserted into the Biodynamic compost pile, and one (valerian) is poured into and/or over the pile once completed.