In the eight lectures on agriculture given at Koberwitz by Rudolf Steiner in June 1924, the biodynamic preparations are the main focus of lectures four and five. After 90 years the biodynamic preparations developed from Rudolf Steiner's spiritual research remain a core part of biodynamic farming practice, an approach based on a spiritual understanding of man's connection to the earth and cosmos and the concept of a self contained farm individuality.
Two complementary spray preparations
The first one, "horn-manure", also called "500" (after E. Pfeiffer's discovery of 500 million bacteria in one gram of the finished preparation), is made from cow manure. This manure is put into a cow horn and then buried for 6 months over winter in fertile soil. It strengthens the vitality of the soil and develops root structure and helps to "push plants up from below".
The second one, "horn-silica" also called "501" is made from finely ground quartz (as fine as flour according to R. Steiner). This is put into a cow horn and buried in the soil during summer for 6 months to gather the Earth's summer forces. This brings a 'light effect' to the plants. It is sprayed over the aerial part of the plants and "draws the plants upwards".
Six preparations normally added to compost and manure
Four of these preparations undergo a fermentation process beneath the earth enclosed within an animal organ sheath. In one case the preparation is first hung up and exposed to the summer forces before being buried in the autumn. A stag's bladder is used for yarrow flowers (502), for chamomile the small intestine of a cow (503), for oak bark the skull of a domestic animal (505) and dandelion flowers are carefully wrapped in the mesentery of a cow (506).
Two of the preparations require no such 'cover'. Stinging nettle is buried directly in the soil for a whole year (504) and from valerian a liquid extract is obtained directly from the flowers (507).
The transformation of living substances (soil, plants, animals and food) through the use of small quantities of alchemically transformed substances – the biodynamic preparations – is an original impulse unique to biodynamic agriculture.