DARK HOLLOW FIELD GUIDE
BD500: Horn Manure Field & Garden Spray
BD500, or horn manure, is one of the foundational biodynamic field preparations. This guide describes the traditional way we stir and apply it at Dark Hollow.
Quick start
- Place one unit of BD500 into roughly 2.5 gallons of water.
- Stir for one hour, repeatedly creating a strong vortex in one direction, breaking it into chaos, and forming a vortex in the opposite direction.
- Apply in coarse droplets to the soil with a brush, branch, bundle of grasses, or a clean sprayer that has not held agricultural chemicals.
- One unit can be used for a garden or spread across roughly an acre.
- Apply the stirred preparation promptly, preferably the same evening.
What BD500 is
In biodynamic practice, fresh cow manure is packed into a cow horn and buried in the earth through the winter. In spring, the transformed material is removed and stored carefully. The finished preparation is dark, earthy, humus-like material rather than fresh manure.
Biodynamic agriculture understands this winter burial and transformation as part of a larger relationship among soil, animal life, season, and cosmic rhythms. BD500 is traditionally used to support the soil-building and rooting side of the farm organism.
Water and vessel
We prefer rainwater when available, with well water as a practical alternative. Use water that is comfortably warm rather than cold. A glazed ceramic or glass vessel is traditional, although a clean food-safe bucket can work. The important thing is to actually do the work rather than let perfect equipment become a barrier.
How to stir
Stir strongly around the perimeter until the water forms a deep vortex. Reverse direction, deliberately breaking the ordered vortex into turbulence, and continue until a vortex forms in the other direction. Repeat this alternation for one hour.
At Dark Hollow, stirring is also a period of attention. We often work outdoors, put away the phone, listen to the place, and hold the farm, garden, animals, and land in mind while stirring.
How to apply
BD500 is a soil spray. Dip a stiff brush, cedar branch, or bundle of grasses into the stirred preparation and cast coarse droplets across the ground, or use a clean backpack or tank sprayer with a coarse setting. The goal is broad distribution, not saturation.
Timing
Traditional biodynamic practice generally favors applying horn manure toward evening, when attention turns toward the soil and root realm. Some practitioners also choose earth/root days or other lunar conditions. We treat those calendar indications as part of biodynamic practice rather than prerequisites: good soil conditions and actually getting the preparation onto the land matter too.