Horn manure 500

What is horn manure (preparation 500)?

Horn manure, known in biodynamic practice as preparation 500, is the most important of the biodynamic preparations and the central soil preparation of the method. It is one of the two field spray preparations, the preparations that are stirred in water and sprayed, as opposed to the compost preparations, which are worked into manure and compost.

The starting material is fresh cow manure. It is packed into a cow horn and buried in the soil over winter. During these months the manure transforms: what comes out of the horn in spring is a dark, crumbly, humus-like and almost odourless mass. Before use, a small amount of it is stirred in water for an hour, the dynamisation, and then sprayed onto the soil in the evening.

The quantities are very small compared with the effect attributed to it: about 300 grams are enough for one hectare. Horn manure is therefore not a fertiliser in the usual sense. It is meant to set processes in motion, not to supply nutrients.

Horn manure and horn silica: the pair of opposites

Horn manure can only be understood together with its counterpart, horn silica 501 (preparation 501). The two form a deliberately designed pair of opposites.

Horn manure works from below, on soil, roots and the dark, moist processes of the earth. It is applied in the evening and onto the soil. Horn silica works from above, on light, ripening and the plant above ground. It is sprayed in the morning into the air around the plants. Rudolf Steiner described this interplay in an image: horn manure pushes "up from below", while horn silica "draws from above", both attuned to each other, "neither too weak nor too strong". Together they cover both the root zone and the light zone.

Where does the number 500 come from?

The numbering of the biodynamic preparations from 500 to 508 dates from 1928. It was originally meant as a code name and has since become a practical abbreviation that is understood internationally. Anyone who says "500" means horn manure.

Origin and context

Horn manure goes back to Rudolf Steiner and his Agriculture Course (GA 327), which he gave at Whitsun 1924 at Koberwitz estate to around a hundred farmers. In the fourth lecture of the course, Steiner describes how the preparation is made from manure and cow horn, how it is diluted, stirred and applied to the field. The course is regarded as the founding text of biodynamic agriculture.

The first preparations were made during Steiner's lifetime: Ehrenfried Pfeiffer took part in making the first batch of horn manure together with Ita Wegman and Günther Wachsmuth. The detailed practice of making and using it, as it is common today, was worked out by the following generation, for example by Eckard von Wistinghausen, Pierre Masson and Walter Stappung, whose works form the technical basis of this entry.

The idea behind manure and horn

Steiner's reasoning for using cow manure in a cow horn comes from his spiritual-scientific world view and is presented here as the original concept, not as a scientific statement. The idea: with its long digestive tract, the cow processes large amounts of feed and releases forces that the animal itself does not need. Steiner saw the horn as an organ that holds these forces back and radiates them back into the body, unlike a deer's antlers, which give forces off. When the manure is packed into the horn and buried over winter, at the time when, in the biodynamic picture, the earth "breathes in" and is open to cosmic forces, these forces are said to gather and intensify in the dung. Steiner himself said that animal manure still contains "the disposition of the I", a term from anthroposophy that marks horn manure as a remedy that gives forces rather than merely supplying nutrients.

Making horn manure

Making it follows a fixed annual rhythm and places clear demands on the material, the horn and the soil.

Manure and feeding

Use fresh, firm cow manure without straw, from cows that have calved. The best quality comes from grazing or grass-clover with hay and straw feeding. Silage or beet-leaf feeding is considered unsuitable. In Central Europe the cow pats are collected in autumn around Michaelmas (end of September), as fresh as possible and stored for no more than a few days.

The right cow horn

The casing is a well-shaped, undamaged horn from a cow that has calved several times. Such horns can be recognised by the "calving rings", constrictions at the base of the horn that form when milk production starts after a calving. A cow horn is relatively heavy, thick-walled and twisted in a spiral. Horns from bulls and oxen are unsuitable: they have no rings, are thin-walled and mostly filled with bone. Boiled or damaged horns are no good either. The manure is packed firmly into the horns until no cavity remains.

Burying over winter

The filled horns are buried about 30 to 50 centimetres deep in deep, humus-rich arable or meadow soil, with the opening facing down so that no standing water can get in. Avoid waterlogging, the root and crown area of trees, and the immediate vicinity of walls and roads. Mark the position of the pit carefully and note it in the farm diary, because after cultivation it is hard to find again. The horns stay in the soil over winter; they are dug up for spring sowing around Easter, and the finished horn manure is removed.

Preparing and storing

The finished horn manure either stays in the horn, packed in peat, or is shaped into balls about the size of a fist and dried slightly in an airy, shady place, just enough that no soil organisms or seeds can develop in it. It is stored surrounded by a layer of peat or untreated coir in a container made of wood, clay or stoneware, cool and frost-free (details under storing the preparations). Horn manure should be made fresh every year; a small leftover can be mixed with fresh material. Wistinghausen and Stappung describe the making in detail.

Effect on soil and plants

In the biodynamic understanding, horn manure works mainly through the soil and the root system, but it also supports growth through the leaf. The guiding idea is not "adding nutrients" but "enlivening the soil". Steiner understood good fertilising as making the earth alive, so that the plant does not root in "dead earth". Horn manure is meant to set this liveliness in motion.

In concrete terms, it is credited with stimulating soil life, encouraging root formation, improving soil structure and supporting the build-up of humus. Experienced practitioners such as Alex Podolinsky described horn manure as the preparation that gives the soil "structure": crumb, aeration, water-holding capacity. It fits this picture that the other preparations add to this basic structure, while horn manure lays the foundation.

From a scientific point of view, there are indications that make some of these observations tangible. Research (summarised, for example, by Scheper, Raupp and Baars 2009) suggests that horn manure contains plant-active, hormone-like substances, and several authors describe an effect as a microbial "inoculation": horn manure introduces and stimulates soil microorganisms. These findings are reported here via the biodynamic literature and have not been checked against the primary sources. They do not fully explain the effect attributed to horn manure, but they show that part of it can be measured.

Using horn manure

When applying it, timing, stirring and quantity decide the result. What counts is to observe the soil and the plants and act accordingly.

When and how is horn manure sprayed?

Horn manure is applied in the evening and onto the soil, when, in the biodynamic picture, the forces are drawn into the earth. The main seasons are spring and autumn, when the earth "breathes out" and "breathes in". Typical occasions are preparing the soil before sowing and planting, freshly mown or grazed land, and autumn after the harvest. In a home garden, choose the moment when the soil has been largely cleared of mulch and green manure and prepared for sowing.

A proven trick: dip the roots of seedlings briefly into the stirred preparation before planting them out, to encourage root formation.

Quantity and water

The rate is about 300 grams of horn manure per hectare per application, dissolved in water. For making it, about four cow horns and one litre of fresh cow manure are reckoned per hectare. For the home garden, Steiner himself gave a practical measure: roughly half a bucket of water with the contents of one cow horn for a manageable vegetable plot. The exact amounts of water and preparation vary with the source, the area and the farm; on large areas the amount of water can be reduced considerably.

In drought, stagnation and disease

In prolonged drought it has proved useful to spray horn manure in the evening and horn silica 501 the next morning to stimulate growth, the pair of opposites working together. Horn manure is also used when growth stalls. It is important to keep this in perspective: horn manure works best on a balanced soil. Where there is heavy over-fertilisation or nutrient deficiency, the preparations are mainly busy balancing out these disturbances and develop less of their actual potential.

Stirring (dynamisation)

Before application, the preparation is stirred rhythmically in water for an hour: create a strong vortex in one direction, break it into chaos, then build a vortex in the opposite direction, for the whole hour. This is meant to transfer the preparation's forces to the water. Stir by hand with a stirring stick or with a stirring barrel. Apply promptly after stirring, because the effect of the stirred preparation fades after about a day. More detail: dynamisation and applying the preparations.

Horn manure and Demeter

For Demeter farms, horn manure is not optional. The Demeter standards require horn manure to be applied at least once a year during the growing season on all land. Using the biodynamic preparations is a defined biodynamic practice and distinguishes Demeter from all other organic associations. For hobby biodynamic gardeners it is voluntary, but it is regarded as the heart of the method (more under Demeter certification).

Effect: what does science say?

A scientific assessment needs a distinction. The isolated effect of the single preparation in its high dilution is hard to prove and remains disputed; the biodynamic concept of forces can hardly be tested with the usual methods. For the biodynamic farming system as a whole, however, there is robust data: the DOK long-term trial of the Research Institute of Organic Agriculture (FiBL), running in Therwil, Switzerland, since 1978, compares biodynamic, bio-organic and conventional farming and shows high soil fertility for the biodynamic system, with higher humus content and clearly increased activity of soil organisms.

It is well established that composting and a living soil promote fertility. The exact contribution of a single horn manure application is not. Promises of healing or miracles do not suit the preparation.