Verily, bones should never be wasted, and phosphorous fertiliser production as part of a self-sufficient operation may require burning them. Gardeners may find they can process left over bones through their wood heaters. In general, burned bones may come from almost any source, and some will burn more easily than others. Burnt bones can be crushed into powder and extracted with vinegar or other organic acids using moderate heat to yield soluble phosphates for liquid applications, and if a little elemental sulphur is needed, the vinegar stage is a good place to add it as a small percentage of the total dry matter.
This crude phosphoric extract is useful diluted and combined with the vermiwash and a homeopathic dose of biodynamic valerian preparation to jump start the phosphorous process. Residual bone ash can be added to composts up to about 8 or 10% of the total raw materials, or it can be dried and scattered thinly under fruit trees and flowering shrubs.