Biodynamic Preparations — 500 (Horn Manure), 501 (Horn Silica), 508 (Horsetail)

Biodynamic farming follows the ideas of Rudolf Steiner (1861-1925), an Austrian educator and philosopher, who set them out in eight lectures in 1924 at the request of a group of farmers in Koberwitz, in present-day Poland. In those lectures Steiner described a farm as a self-sustaining, closed organism, producing all of its own inputs. Like organic farming, biodynamics rejects synthetic inputs, and organic certification is the minimum requirement for biodynamic certification. The major difference is that biodynamics requires special preparations, numbered 500 to 508, either sprayed on the vines in tiny quantities or added to the soil through compost. Steiner outlined nine preparations, made from cow manure, quartz (silica) and seven medicinal plants, though he did not single-handedly invent biodynamics: today's understanding of it evolved over several decades through the work of his followers. Three of the nine are used as sprays: 500 (horn manure), 501 (horn silica) and 508 (common horsetail). The other six, 502 to 507, are applied to the vineyard through compost.

• 500 and 501 begin as cow manure and ground quartz, each buried in cow horns in the soil
• 508 is made from common horsetail (Equisetum arvense)
• Some preparations are first transformed in animal organs used as sheaths; the organs themselves are not used on the vineyards

Preparation 500 starts as manure from a lactating cow, placed inside a cow horn and buried in the soil over winter. When the horn is dug up, its contents, called horn manure, are stirred in water and sprayed on the soil in the afternoon. Preparation 501 starts as ground quartz, made into a paste with water, placed inside a cow horn and buried over summer; its contents, called horn silica, are stirred in water and sprayed over the vines at daybreak. The horns may be re-used as sheaths. Preparation 508 is made from common horsetail (Equisetum arvense), prepared either as a fresh tea, which is applied to the vines, or as a fermented liquid manure, which is applied to the soil. Before spraying, small quantities of material are added to water and dynamized: the liquid is swirled in one direction until a vortex forms, then in the opposite direction until another vortex forms, and so on, for up to an hour.

• The Demeter Farm Standard calls for 500 to be applied in the later part of the day as droplets that come in contact with the earth, and 501 in the early morning hours as a fine mist that settles onto the foliage
• 508 can be combined with Bordeaux mixture (copper sulfate) and wettable sulfur and sprayed on vines or soil during the waxing moon
• A single horn of preparation is used per hectare
• Demeter requires 500 and 501 to be applied every year; the compost preparations are used whenever compost is made, and Demeter USA requires them at least once every three years

Each spray has a stated purpose in biodynamic practice. Preparation 500 is meant to stimulate soil life and root growth; the Demeter Farm Standard describes it as a soil spray to stimulate root growth, humus formation and microorganism development. Preparation 501, a foliar spray, is meant to encourage photosynthesis and ripening. Preparation 508 is meant to lessen the effect of fungus, and the Demeter standard lists it for disease control. Demeter prohibits chemical inputs except copper, used to fight mildew, and sulfur, of which small doses are suggested. These are the purposes practitioners and certifiers give for the sprays; what the sources say about the evidence is set out below.

• 500: meant to stimulate soil life and root growth
• 501: meant to encourage photosynthesis and ripening
• 508: meant to lessen the effect of fungus
• Biodyvin and Demeter rules can be stricter than organic alone, for example less use of copper sulphate per hectare

Biodynamic certification is not government regulated; it is overseen and granted by private institutions. Demeter, the first biodynamic certification organisation, was established as early as 1928 and regulates all manner of farms, not just vineyards. Unlike organic certification, where a single block may be certified, Demeter requires the entire property to be farmed biodynamically, with at least 10% of the land set aside for natural habitat. Biodyvin is a certification body for European wineries only, and Austria-based respekt-BIODYN is more restrictive in terms of copper usage. In Savennières, in the Loire, Nicolas Joly's parents bought the Château de la Roche aux Moines in 1962; its vines included La Coulée de Serrant, which Joly took over in 1977. He trialled Steiner's methods on a small scale for a year or two, then converted the entire estate, which has been fully biodynamic since 1984. La Coulée de Serrant is a single-vineyard appellation, originally planted by Cistercian monks in 1130.

• Demeter: established as early as 1928; certifies all manner of farms, not just vineyards
• Biodyvin: strongly recommends the Maria Thun calendar and requires growers to keep a farm diary of the timing of all treatments
• Nicolas Joly, La Coulée de Serrant, Savennières: fully biodynamic since 1984

A GuildSomm Master of Wine essay describes research into biodynamics as sparse, notes that many studies group organic and biodynamic vineyards together, calls the tiny quantity used (a single horn per hectare) one of the most common criticisms of biodynamic methods, and separately offers the argument that any perceived benefits are most likely due to growers spending more time and attention on their land. GuildSomm's Kelli White writes that, from a scientific perspective, we really don't know how biodynamics works, and that the majority of evidence remains either anecdotal or too entangled in variables to be definitively interpreted. A UC Davis research summary of a trial by Reeve and colleagues (American Journal of Enology and Viticulture, 2005) describes a comparison from 1996 to 2003 in Ukiah, California, of a certified organic vineyard and one that transitioned to biodynamics in 1996, reporting no differences in soil, leaf tissue analysis, yield, cluster counts and weights or berry weights; yield to pruning weight ratios did differ, with the biodynamic vines better balanced. The trial was a long-term, replicated 4.9-hectare study on a commercial Merlot vineyard. On must composition the two readings differ: the UC Davis summary says the differences observed were too small to be of any significance and that the authors believe it is unlikely that biodynamic preparations contribute to grape quality, while the paper's abstract reports significantly higher (p < 0.05) Brix and notably higher (p < 0.1) total phenols and total anthocyanins in 2003 for the biodynamically treated winegrapes, calls the question of whether the preparations augment winegrape quality unclear and controversial, and concludes that the preparations may affect winegrape canopy and chemistry but were not shown to affect the soil parameters or tissue nutrients measured in the study. A peer-reviewed five-year experiment listed in Sources, set up in 2016 in a commercial vineyard in Switzerland, compared preparations 500 and 501 with an organic control (blocks that received water instead of the preparations): none of the vine and berry physiology parameters showed significant differences except photosynthesis, which was higher with the preparations at one time point; the soil's physical properties were not influenced, and the preparations neither led to significant differences in soil fungal diversity nor seemed to impact the soil fungal communities. In the first four years of a long-term field trial in Geisenheim, Germany, also listed in Sources, biodynamic management had more pronounced effects than organic management in terms of enhanced soil fertility and reduction of vegetative growth; the authors write that the mode of action of biodynamic preparations is still not well understood. A 2019 systematic review listed in Sources found that organic and biodynamic treatments, taken together, showed 21% lower growth and 18% lower yield than conventional viticulture, and observed no overall differences in berry composition, juice or wine quality among management systems.

Biodynamics holds that vineyard and cellar tasks should be timed by the biodynamic calendar to harness planetary, solar, stellar and especially lunar cycles. Demeter encourages adherence to the calendar but does not require it, while Biodyvin strongly recommends the Maria Thun calendar. Thun's calendar is based on sidereal rhythms and sorts days into fruit, flower, root and leaf days, depending on the astrological sign that lies behind the moon: fruit days correspond with fire signs, flower days with air signs, root days with earth signs and leaf days with water signs. GuildSomm's Kelli White writes that Thun's own studies are not considered credible by the scientific community at large, and that Hartmut Spiess, working with Thun, attempted to confirm her results but could not. According to biodynamic producers, fruit and flower days are the best for drinking wine. In a peer-reviewed study listed in Sources, nineteen New Zealand wine professionals tasted 12 Pinot Noir wines blind on a fruit day and a root day; the type of day did not systematically influence any of the wine characteristics evaluated.

• Fruit days: fire signs; flower days: air signs; root days: earth signs; leaf days: water signs
• Demeter: calendar encouraged, not required; Biodyvin: Maria Thun calendar strongly recommended

Primary sources: https://coststudyfiles.ucdavis.edu/uploads/cs_public/62/3a/623a8e4d-ba4c-4c7b-9f13-389e17fd1928/16winegrapebiodynamicmendocinofinaldraft61416-1.pdf, https://wineserver.ucdavis.edu/sites/g/files/dgvnsk2676/files/research-summaries/69%20biodynamic%20vs%20organic.pdf, https://www.ajevonline.org/content/56/4/367 (Reeve et al., American Journal of Enology and Viticulture, 2005), https://oeno-one.eu/article/view/7218 (Rienth et al., OENO One, 2023), https://oeno-one.eu/article/view/2470 (Meissner et al., OENO One, 2019), https://www.ajevonline.org/content/early/2019/02/14/ajev.2019.18047 (Döring et al., American Journal of Enology and Viticulture, 2019), https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0169257 (Parr et al., PLOS ONE, 2017). Secondary sources: https://www.guildsomm.com/research/mw-perspectives/b/mw-perspectives/posts/the-relevance-of-biodynamics, https://www.guildsomm.com/public_content/features/articles/b/kelli-white/posts/contemporary-biodynamics, https://www.guildsomm.com/public_content/features/articles/b/guest_blog/posts/organic-biodynamic-and-natural-wines-explained, https://www.decanter.com/learn/biodynamic-wines-explained-472503/, https://www.decanter.com/learn/sustainability-in-wine-explained-478803/, https://www.decanter.com/premium/nicolas-joly-decanter-hall-of-fame-2025-565729/, https://www.decanter.com/features/a-man-of-principle-249033/, https://www.decanter.com/features/biodynamics-fruit-and-root-days-246375/. Last verified 2026-11-02