The Discovery of Horn Clay and Biodynamics

By Hugh Lovel

With thousands of lectures and uncounted insights Rudolf Steiner launched anthroposophy as a study of human wisdom. With extraordinary learning in both the classics and modern science, Steiner combined his immense erudition with innate clear seeing gifts to forge a vision of the world that at once was both spiritual and scientific.

This was an awesome, overwhelming act for others to follow. To date it would be hard to find a more thoroughgoing response to the need for a scientific world view with soul, purpose and wisdom. Unfortunately, it is characteristic of such figures and movements that a core of orthodox adherents develops which ossifies into a cult of true believers unable to think for themselves, dependent upon quotation from scriptures. Biodynamic agriculture, which grew out of Rudolf Steiner¹s work, has not escaped some measure of this. For one thing Steiner’s insights, even though more than 75 years old, are still ahead of our universities.

In lecture two of his agriculture course, Steiner touched on the importance of clay as a mediator between the lime and silica poles of nature. He emphasized clay’s primary role in conducting the silica forces, which develop deep within the earth, upward for plant development towards fruit and seed. No matter how else clay is described or what we do to make it fertile–all is of secondary importance. The important thing is clay promotes the upward stream associated with silica.

Needless to say this is revolutionary thinking. Soil testing only measures the extent clay acts as a reservoir of nutrients. After testing the soil, we may apply lime and other nutrients, but the key question really is how to move these nutrients upward to the fruit. What moves the nutrients is the silica stream, with clay as the conductor. Reading Steiner’s agriculture shows he had encyclopaedic knowledge and insight to share–with very limited time to share them. He could only hit the high spots, going on to the next insight and the next.

He said in lecture two that later he would give recommendations for treating clay to better conduct the growth forces welling out of the earth. However, later he failed to do so. We know he meant to give a second agriculture course, but he fell ill and died without doing this. So for 75 years biodynamic agriculture proceeded with horn manure (BD 500) and horn silica (BD 501) but no horn clay. Steiner didn’t give enough indications, so who knew how to pack the horns or use the finished horn clay? Characteristic of the paralysis of true believer cults, little was done by experiment.

With changing a light bulb, it is clear that a minimum of one, though possibly under some conditions more, persons are necessary. And experiments could determine how many are required under what conditions. With making and using horn clay things are similarly clear cut. Experiments could have proceeded at any time. Now after 75 years they have. The results are most interesting.

“Let me remark here that if we are dealing with a soil that does not carry these influences upward during the winter as it should, it is good to furnish that soil with some clay, the dosage of which I will indicate later.” –Rudolf Steiner

My first experience with biodynamic horn clay was at Michael Topolos’ winery in Forestville, California. This merlot vineyard adjoined a busy two lane highway, with pollution near the road. WE applied Horn clay here as part of a back-to-back sequence of all of the BD preps, and a belt of selected plants were established at the boundary by the road.

More than twenty years of biodynamics makes me aware of subtle nuances. What I perceived at the roadside was gas, oil, rubber and asbestos. What I perceived stepping down into the vineyard below the road was soil, foliage and ripe grapes. Just a couple steps made a remarkable difference. Up on the road I could see in my mind’s eye a protective membrane enveloping the vineyard. The difference between being within this membrane and being outside was like the difference between life and death.

The horn clay created a dome, like a plastic greenhouse covering, which enveloped the entire vineyard and protected its biodynamic energies. All of the BD preps held together and worked in concert. Though this vineyard was only a few years biodynamic, this was best interaction of the preps I had ever seen including that on my own farm.

From then on I knew I must investigate horn clay beyond my philosophical discussions with Hugh Courtney and Harvey Lisle. We took the contemplation of horn clay into use. With horn manure and horn silica we only had the up and down forces with no middle, no coordination holding things together. Clay is that glue. With horn clay plants not only work into the atmosphere–they are held there to fruit and ripen. Moreover, with horn clay the soil is stimulated to better receive what works back into it when digestion occurs.

Horn clay goes to the very basis of how and why biodynamics works. Back when Rudolf Steiner gave his agricultural lectures in 1924 he emphasized the importance of clay as conducting the silica factor welling up from deep within the earth. This silica factor builds up over the winter and causes plants to grow strongly in spring. Unfortunately in his agriculture , despite his promise, Steiner failed to indicate how the soil should be dosed in regard to clay. When talking about making the horn silica he mentioned the horn cavity probably should be capped off with a plug of clay to seal it. Those who worked with him in Switzerland were taught to make both horn manure and horn silica with a clay plug sealing the open end. However, since Steiner was not explicit in his agriculture course that this clay should be incorporated in the finished horn preparations it became common practice to unearth the horns, take out the clay and throw it away and use the horn manure and horn silica without any clay admixture.

The idea of making horn clay was part of biodynamics from the beginning. In this regard Walter Stappung’s booklet Die Dünger-Präparate, published in Switzerland in 2000, cites Voegele (1926), Lippert (1938) Remer (1980) and Willis (1999). We got the idea of making horn clay from a lecture delivered almost a decade earlier by Gunter Hauk. When asking Gunter how to make the horn clay the response was “No one knows. Steiner didn¹t give any indications.” However, in the process of making biodynamics work so that it made farms self-sufficient and addressed all issues of agricultural importance as Steiner clearly intended it to Willis found he had to make horn clay. Horn clay goes to the basis of how and why biodynamics works.



Geologists know that silica cooks up out of the Earth’s mantle. High mountains are thrust up by the rising silica forces within the earth. In fact it is only through the uplifting, vertical forces of silica that such heavy elements as gold, silver, platinum, lead and uranium are brought to the surface. In plants the silica forces work on the vertical axis driving plants toward fruit and seed. It is through the uplifting activity of silica that the lime elements such as calcium are carried up into leaf, fruit and seed. Steiner pointed out that the outer planets, Mars, Jupiter and Saturn, work upward toward fruit and ripening through the siliceous substances of the Earth. However, the silica forces do not move upward into plants very well without clay as clay governs the ebb and flow of sap within the plant. This is why tomatoes do best in clay soils while potatoes produce better in sandy soils. With tomatoes the silica forces must rise very high in the plant, while with potatoes it is better if this does not occur. In sandy soils where clay doesn’t convey the silica forces so strongly toward fruit and seed potatoes won¹t waste their energies on flower and fruit. Instead the silica forces stay below the surface where potatoes form.  For some other examples, Georgia peanuts and soybeans do ever so well on heavy red clays near Columbus while onions do much better in lighter soils near Vidalia. There are many corollaries to this.


As the Sun evolved from a new star to its present form it converted hydrogen and helium into denser elements. These denser elements often are ejected from the Sun as ionized plumes called solar prominences or coronal discharges. When these ions strike the Earth’s magnetic field they stream in over the poles causing the northern and southern lights.

Earlier in the Sun’s evolution much carbon was given off. In later ages there have been more heavier elements like magnesium, calcium, iron and copper. This is why so many coal deposits are overlayed with limestone. Our planet has long collected material from the Sun, laying it down horizontally as sediments. Just as silica carries vertical forces, lime carries horizontal forces. Every housewife knows that dust accumulates in her closets, but how much more dust settles in open fields?

The significance of lime working horizontally is that it fills things out. So it is of great importance in leaves which spread out horizontally and catch sunlight. It also is lime that fills out the apple, grape or watermelon and makes them juicy and fat. And it is lime that gives legumes like beans or alfalfa the ability to draw nitrogen from its dead form as an inert gas in the air into the life of the soil.


On the periodic table of the elements berylium, magnesium, calcium and strontium are group II, alkaline substances which grasp and hold other elements. On the other hand carbon, silicon and germanium are group IV substances which are very free in their chemical nature. In between  groups II and IV are the group III elements of boron, aluminum and galium. These are the mediators as they both give and take. Clay basically is aluminum silicates, though, of course, clays can contain a wide variety of other minerals. Clay is plastic, absorbent, holds and releases water extremely well and is easily molded into various forms.

According to ancient wisdom man is made of clay, and clay relates to the heart and circulation, as well as the feelings and emotions which bridge between the brain and the guts, the thinking and willing parts of the human being.


Taken by themselves chemical elements in their pure states are lifeless. This is even true of oxygen, the carrier of life. Diatomic oxygen gas in the atmosphere is lifeless. But when oxygen combines with other elements life comes into the picture. Thus in their pure states calcium and magnesium or carbon and silicon are lifeless. But their oxides, lime, silica or carbon dioxide provide the basis for life as we know it.

This is just as true for aluminum, which mediates between lime and silica. Pure aluminum is lifeless. But its oxide, alumina, forms the basis for clay and in combination with silica is clay. As such alumina directly channels the expansive, cosmic, formative, life giving forces of silica into interaction with lime and all the interplay going on between the lime and silica. Not that there is much aluminum in our bodies or in plants. There’s only a small amount. But it is no accident that the Bible identifies man as “made of clay.” Truly it is clay that holds us together, receiving and retaining the forces of order, form and energy that give us life.

How BD Works

Applying the BD preps establishes patterns that organize the energies and substances in nature. The patterns of light and warmth associated with silica bring about photosynthesis, blossoming, fruiting and ripening in the atmosphere where the elements of air and fire are organized in plants. The patterns of tone and life associated with lime bring about digestion and nourishment in the soil where the elements of water and earth are organized by the soil food web. In between these are the ebb and flow of sap in plants that brings sugars down from above to the roots and brings nutrients back up from the soil.

The biodynamic practice of burying cow horns with quartz powder, cow manure and bentonite in them focuses the cosmic pattern energies on the materials in the horns and the material within the horn cavity resonates (inaudibly) like a bell ringing. Ever hold a conch shell to your ear and hear the roar within? The cow horn does something similar though it resonates to the cosmos rather than just to the sea.

This imparts a tremendous pattern force to the horn preparations. Then when these preparations are stirred and sprayed the droplets act as seeds to establish resonant patterns that, in the case of horn silica enhance photosynthesis and ripening, in the case of horn manure enhance digestion and nourishment, and in the case of horn clay enhance the ebb and flow of sap within the plant.

What Horn Clay Does

It doesn’t do all that much good to enhance photosynthesis, fruiting and ripening in the above ground part of the plant and boost the digestive and nutritive activities in the soil at the plant¹s roots if there is insufficient give and take occurring between these two polarities. By itself horn clay doesn¹t do so much. But used in conjunction with horn quartz and horn manure it works as follows.

As its first activity horn quartz enhances photosynthesis, the manufacture of sugars which powers all the complex chemistry in the leaf. The horn manure yields a rich and active soil food web. Yet it is the horn clay that is so key in boosting the ebb and flow of the plant¹s sap resulting in a lively exchange between roots and tops. When the sap in the plant ebbs into the roots sugars and other compounds are exuded into the soil near the plant¹s feeder roots. This provides energy for the mycorhyzae, azotobacters and other soil food web organisms so that nitrogen is fixed and nutrients are elaborated from the soil. As the sap is sucked back up into the plant and flows back to the growing tips these nutrients are taken up in abundance.

Perhaps the most important aspect of this relates to the most mobile nutrient of all, nitrogen. When nitrogen is supplied from external sources it will be available to plants as salts, whether these are oxidized to the nitrates, reduced to ammonia or in some intermediary state such as urea. Nitrogen salts are very soluble and mobile and they are taken up very readily by plants. If they are abundant they depress nitrogen fixation by microorganisms and are taken up by plants to exclusion of more complex nitrogen compounds such as amino acids. This results in salty, watery protoplasm in the leaves and growing tips and the plant must expend considerable energy in elaborating these nitrogen salts into proteins and into its DNA. This can never produce a plant that fulfills its genetic potential.

However, if the plant is sending sugars to its roots and feeding azotobacters which are fixing atmospheric nitrogen the plant gets its nitrogen requirement in the form of amino acids rather than nitrogen salts. These are assembled without further ado into proteins and the plant can manifest the full complexity of its genetic templates so that its cells are turgid, cell structure is dense, brix is high, protein is high and flavors are out the roof. Then all the toxic rescue chemistry becomes superfluous if not damaging, weeds lose out in the race to keep up with larger seeded robust crops, insects and diseases fall by the wayside and the bottom line is NO FERTILIZER COSTS.

The results obtained with a BD program using horn clay are best when NO salt fertilizers whatsoever are used, and especially no salt nitrogen. Compost applications at modest levels may be advisable, especially on land where silage or hay is cut and the growth is removed.

However, heavy applications of compost are inadvisable because the nitrogen compounds in the compost will oxidize to the nitrates and having nitrogen salts present in the soil dilutes the plant¹s sap and makes its protoplasm salty and watery. The key is to get the exchange going between sugars from the leaves and amino acids from the soil so that the plant maxes out and high yields of the finest quality are obtained.

Doing Horn Clay

Builder¹s supply stores commonly sell sodium bentonite clay, which is cheap and makes a very good horn clay. Other clays will do and some may be particularly superb, but bentonite is one of the classic clays with good water absorption and release and a good cation exchange capacity. Getting cow horns may be more of a problem, but if you know of folks in the slaughter business these too can be obtained. The best horns are from mature cows living on free range that have had several calves. It is important that the horns have heavy weight compared to their volume, because such horns have a stronger resonance or better “ring.”

Ideally horn clay should span the entire year in the horn, both summer and winter. Clay functions differently in summer than in winter and both the ebb and flow functions should be present. This means one can bury horns filled with (moisten first) bentonite at the spring equinox and unearth them after the following spring equinox. Or one can bury them at the fall equinox and go all the way until the following fall equinox passes. But in case one has the basic patterns of full year horn clay and one wants to emphasize either just the summer or just the winter patterns one can bury horns filled with clay from spring equinox to fall equinox (summer horn clay) or bury them from fall equinox to spring equinox (winter horn clay).

Application by stirring and spraying can cover 15 or 16 acres per barrel full. With a stirring rod suspended from a tripod one gets the water in the barrel moving in one direction, builds it up, puts a lot of energy into it, gets the vortex really whirling and draws the stirring rod in to center where it spins up with increased angular momentum as it nears the axis. And then. . . at the center it comes to rest with the whole barrel of solution spinning round it. You can see the etheric vortex lines cut across with the counter vortex lines of laminate water layers. These vortex/counter-vortex lines form a pattern like a great sunflower, such as Van Gogh painted so often. Each cycle grows, matures, senesces and is swept away.

The stirrer takes the pole back out of center, enters in the vortex in the counter fashion, and disrupts the dying cyclone into seething . . .chaos . . .Then winds into a new vortex–stoking it with energy and building to crescendo once again. Generation after generation goes the dance of life. Vortex/counter-vortex, leading, building, evolving inexorably to a universe of higher orderedness.

Then the spray is filtered and applied with a spray rig. Horn quartz is sprayed in the early morning as a mist into the atmosphere. It is supposed to evaporate upwards into the atmosphere. Horn manure is sprayed on the soil in late afternoon in very large droplets. It is supposed to sink in, and if one can disc it in or plow it down it seems to work better. With horn clay one wants a moderately fine spray in the afternoon to cover the surface of the soil or the lower trunks of trees so as to form a skin or diaphragm at the surface to mediate between the dynamic patterns of the atmosphere and the soil.


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