Manure in biodynamics
Manure is the central farmyard fertiliser of a biodynamic farm. Cow, horse, goat and chicken manure each have their own properties; stable manure, solid manure and slurry are the basic forms of storage.
What is meant?
In biodynamic practice, manure is a central farmyard fertiliser: the organic excretions of the farm animals, mixed with bedding, composted and returned to the land. In the biodynamic view, it is the material link between animal, soil and plant and thus a cornerstone of the farm organism.
In English, "dung" usually means the droppings themselves and "manure" the droppings mixed with bedding and used as fertiliser; in everyday use the two words are often interchangeable. The main distinctions are by animal species and by form of storage.
Types of manure by animal
Cow manure is the most important type in the biodynamic canon. In the Agriculture Course, Steiner gives it a special place, with the cow as the bearer of the digestive and transforming power typical of biodynamics. Cow manure is relatively low in nitrogen and rich in fibre, with a balanced mineral content, and is regarded as "warm and calm", well suited as a compost base in which the compost preparations can take effect. The preparation horn manure 500 is also made from cow manure.
Horse manure is hotter and more intense: higher in nitrogen, faster to decompose, the classic material for hotbeds and cold frames. In biodynamic practice it is common on farms that keep horses, but it is not a required element.
Goat and sheep manure are fine-grained and dry, with a high potassium and nitrogen content. They are traditionally valued for berries, vines and fruit; many biodynamic farms in southern Europe and the Alps work mainly with small ruminants.
Chicken and poultry manure are very rich in nutrients and must be composted or heavily diluted before use, because fresh they can damage plants. They play a minor role in biodynamic practice, mainly as an addition to the main manure on farms that keep chickens.
Pig manure is not widespread; pigs are kept less often than ruminants in the biodynamic tradition. When it does occur, it is usually diluted heavily with straw and worked into the main compost.
Forms of storage
Stable manure is the classic form: animal excretions plus bedding (straw, hay, wood shavings), trodden down in the stable and kept moist, then stored on the manure heap as solid manure.
Solid manure is compacted, stored manure, firmer than when it was produced and further along in decomposition. In biodynamic practice, solid manure is usually processed further into compost, treated with the compost preparations and matured for months before it goes onto the field.
Slurry is the liquid form: animal excretions with little or no bedding, collected in tanks or pits. Biodynamic practice views slurry critically, because it can lead to a one-sided nitrogen effect and to soil compaction when spread. Demeter farms keep slurry to a minimum where possible and prefer solid manure compost. Where slurry does occur, it is treated with barrel compost or with the compost preparations before it is spread.
Manure compost is the end product: solid manure inoculated with the compost preparations and matured, which goes onto the field. It is the central source of fertiliser on a biodynamic farm and the point at which the effect of the preparations enters the soil's cycle of substances.
What biodynamics sees differently
The biodynamic method differs from the rest of organic farming in how it values manure, not mainly in quantitative terms (nitrogen, phosphorus, potassium) but in qualitative ones. What matters is not the nutrient calculation but how the manure has been treated: how long it has been stored, whether it has been inoculated with the preparations, whether it comes from the farm's own stable or has been bought in.
In the classic farm organism, the farm's own manure from its own livestock is considered the best. Bought-in manure is possible but less valued, because it brings in the "information" of another farm. The Demeter standards limit the share of bought-in organic fertilisers; they set out the details themselves.
In practice
On a classic biodynamic farm, the manure cycle runs like this: animals in the stable; manure and bedding onto the manure heap; solid manure compost inoculated with the six compost preparations; left to mature for six to twelve months; mature compost spread on the land before the growing season. The quantities depend on the farm system; figures of 15 to 25 tonnes per hectare per year are given.