Prepared horn manure 500P-502-507 | A soil spray used by some practitioners of Biodynamics. It was created by Alex Podolinsky, Australia’s best-known biodynamic thinker and practitioner. Podolinsky’s preferred name for his preparation is 500P; but here and to be consistent in indicating by code number exactly which Biodynamic preparation or preparations each spray or treatment contains (See the Biodynamic preparation numbers 500-508) a slightly elongated description of it is used. Thus here the term Prepared horn manure 500 + 502-507 is used and indicates exactly which seven (of nine) biodynamic preparations it contains.

Background | Podolinsky felt European biodynamic farmers’ insistence on stirring their spray preparations by hand rather than mechanically meant that only small areas of cropland would ever become biodynamic. ‘The world’s population has increased four times in my lifetime and we can’t feed everyone with small-scale, backyard biodynamic farming,’ Podolinsky told me. Podolinsky reminded his critics that Steiner had accepted mechanical stirring as valid when giving the Agriculture course. Podolinsky argued that mechanical stirring was capable of producing more consistent results than hand stirring, like deeper vortices in the water (although for recent advice to the contrary see Chapter 4). Podolinsky also felt Europe’s biodynamic farmers had shown themselves to be no better qualitatively than their organic counterparts because their solid biodynamic preparations 500 + 502-506 appeared so dry as to be incapable of carrying the formative life forces lacking in contemporary agriculture. For more on this debate see Storing Compost Preparations – Dry or Moist?

In his adopted Australia, Podolinsky began refining his method for large-scale biodynamics. This, coupled with his interest in Ehrenfried Pfeiffer’s field spray concentrate led Podolinsky to develop a spray which he called the Prepared 500. Some Australians refer to it as “powercow”, while another name for it is prepared horn manure or 500P, although Podolinsky maintained that it was misguided to describe horn manure 500 as any kind of ‘manure’.

Making Prepared horn manure | It would appear 500P is made from freshly excavated Horn Manure 500 to which are added the six Biodynamic compost preparations 502-507. The whole is aged for 6 (or 12) months in copper containers. When needed, the material is diluted in water, dynamized and sprayed in the same way as Horn Manure 500. The 500P is said to build organic matter quickly and can deepen topsoil (hence its nick-name of ‘powercow’ in Australia). Its main attribute is to allow a copious if shallow root system to develop. This would appear to be useful in Australian conditions: no recent glaciation, arid conditions, risk of saline sub-soils due to irrigation. 

Podolinsky’s ‘prepared 500’ spray shares similar advantages to those offered by Maria Thun’s barrel compost spray 502-507 in being a less labour-intensive way of getting the six Biodynamic compost preparations 502-507 on the land, with the bonus of combining it with Horn manure 500 in a single spray. Devotees of ‘prepared 500’ say it initiates biodynamic processes more strongly in the soil than Maria Thun’s barrel compost 502-507 which (they claim) merely helps soil generate and digest organic matter (eg fallen leaves or recently ploughed in cover crops). Neither Podolinsky nor Thun maintained prepared 500 or barrel compost were to be thought of as a long-term substitutes for solid biodynamic compost 502-507, however.

Using Prepared 500: This is stirred (dynamized) in water and sprayed on soil in the same way and in the same volume as Horn manure 500.

Critique of Prepared horn manure | The late French consultant François Bouchet suggested Podolinsky’s ‘prepared 500’ risked creating an unwelcome opposition between two force poles, namely between Horn Manure 500 which stimulates growth forces (building of organic matter, enhanced root expression), and the six Biodynamic compost preparations 502-507 which exert forces to aid the correct decomposition of organic matter in compost (decomposition forces). If he (Bouchet) was correct one might expect, all other variables being equal, a wine grown using 500P might exhibit a less clearly defined centre or backbone compared to one grown using (classic) Horn manure 500 due to excess vegetation, enhanced risk of fungal disease and reduced grape ripeness. Bouchet claimed that while ‘prepared 500’ may build topsoil by “animating” it, it does so only in such a way as to cause plant roots to remain in the topsoil, encouraging shallow (horizontal) rather than deep (vertical) rooting.

While this may suit market gardeners growing mainly annual crops like vegetables, Bouchet saw it as problematic for perennial crops like vines reliant on a permanent, thus invariably deeper or at least more extensive root system to express their sense of terroir. For this, classic horn manure 500 remained the best tool, Bouchet said (see the Lime-Silica polarity for why). Yet what appears a drawback from Bouchet’s European perspective may be a boon for those whose subsoils suffer salinity as a result of over-irrigation. Prepared 500’s popularity in Australia may thus be a reflection of how important irrigation is to farmers there. Sub-soils which exhibit both salinity and sodicity as a result of irrigation poison crops which root too deeply. Hence a soil spray like ‘prepared 500’ which builds topsoil without necessarily encouraging deeper rooting appears to have its place.

Patented preparation?The other aspect of Prepared Horn Manure 500P is that the precise way it is made appears to be almost like a secret, given by Mr Podolinsky only to a select group of people. This contrasts with how the Biodynamic method was publicly and exhaustively described in detail by Rudolf Steiner in his 1924 Agriculture Course. When Vincent Masson, son of the (now late) Pierre Masson, spoke at the 1914 UK Biodynamic Agri-Culture conference (details below) he provided plenty of detail regarding how he made both Horn manure 500 (‘the horns should not touch each other in the ground’) and Horn silica 501 (from ‘milky white quartz from the French alps’). Vincent also gave full details on his preferred moment to add the Biodynamic compost preparations 502-507 to compost piles (‘right at the start when the pile is being made’). About the precise manufacture of Prepared Horn manure 500P Vincent Masson said nothing substantive whatsoever, despite presenting a detailed series of slide images showing the effects of 500P on soil.

This silence is perhaps unsurprising, given that on page two of the second edition of the English language version of his father Pierre’s book, ‘A Biodynamic Manual’ which Vincent also revised and edited (see Bibliography, below), it states ‘500P should only be made by experienced Biodynamic practitioners who have been specifically trained, so detailed instructions are not provided here.’

The Masson position is unambiguous that 500P is and I quote ‘significantly more effective than the traditional [Horn manure] 500 preparation. [500P] is suitable for use everywhere and replaces [Horn manure] 500 in most cases.’

I disagree with this claim, based on my observations of the taste differences of wines grown using 500 versus 500P over the last 20 or more years. I find wines grown with 500P can lack a centre. This is most clearly detectable in 500P wines from France’s version of Australia, namely the drier areas of Mediterranean France like Roussillon, Languedoc, southern Rhône, and Provence. If 500P was so good why do only three Australian wineries (as of mid-2018) appear to have Demeter certification in Australia, not forgetting that Alex Podolinsky acquired the right to use the ‘Demeter Bio-Dynamic’ trademark there in the 1950s (this is why Demeter Australia is not part of Demeter International). Biodynamics is growing steadily everywhere worldwide. Except in the country that invented the Biodynamic spray ‘suitable for everywhere.’

Steiner said to consider the suggestions he made in his Agriculture Course as not being the final word, and that farmers should experiment and not get stuck in a timewarp. I agree, and the work done by Podolinsky and the Massons is not in any way invalid. But I cannot believe that Steiner (and those who worked him) would have spent so much time and effort creating and explaining the importance and distinct differences between the role and preparation of compost, the role and preparation of the 6 compost preparations, and the role and preparation of horn manure 500 if what he had really wanted to say was: ‘you know what, on second thoughts just lump the six compost preps 502-507 in with the Horn manure 500. This will actually be significantly more effective than the 500 preparation I just spent all that time telling you about earlier so that each one of you would have exactly the same knowledge as me with nothing hidden. In fact, 500P will replace the 500 in most cases. Just remember to avoid trying to make it yourself, unless you are an experienced biodynamic practitioner and have been specifically trained.’


Monty Waldin., Biodynamic Gardening (Dorling Kindersley, 2015).

Monty Waldin., Biodynamic Wine (Infinite Ideas, 2016).

Pierre Masson., ‘A Biodynamic manual‘ (2014, Floris Books, Edinburgh, second edition, revised and edited by Pierre and Vincent Masson.Translated by Monique Blais), p.20-22.

Vincent Masson., talk given on Friday evening 31st October 2014 at the Biodynamic Agri-Culture – A Matter of Life Conference hosted by the Biodynamic Association UK at Glasshouse College in Stourbridge in the West Midlands of England.