Bone meal
Bone meal is a mixture of crushed and coarsely ground bone
Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...

s that is used as an organic fertilizer
Organic fertilizer
Organic fertilizers are naturally occurring fertilizers .Naturally occurring organic fertilizers include manure, slurry, worm castings, peat, seaweed, humic acid, and guano. Sewage sludge use in organic agricultural operations in the U.S...

 for plants and formerly in animal feed. As a slow-release fertilizer
Fertilizer is any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use...

, bone meal is primarily used as a source of phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...


Bone meal once was often used as a human dietary calcium supplement. Research in the 1980s found that many bone meal preparations were contaminated with lead and other toxic metals, and it is no longer recommended as a calcium source.

As a fertilizer, the N-P-K ratio
NPK rating
NPK rating is used to label fertilizer based on the relative content of the chemicals nitrogen, phosphorus, and potassium that are commonly used in fertilizers....

 of bone meal is generally 4-12-0, though some steamed bone meals have N-P-Ks of 1-13-0. Bone meal is also an excellent organic source of calcium.

Organic fertilizers usually require the use of microbes/bacteria in the soil in order to make the nutrients in the fertilizer bio-available. That can result in irregular release of phosphorus/calcium. In sterile potting soil, there may be no microbes to release the nutrients.

Finely ground bone meal may provide quicker release than coarsely ground.

Phosphates do not easily pass through soil. So mixing the bone meal with the soil or putting it in the planting hole can help.

Bone meal is frequently used in preparing holes for blooming bulbs, for the phosphorus. It may help tomato plants prevent blossom end rot. However, blossom end rot can happen even though sufficient calcium is present if watering is irregular. High phosphorus fertilizers are also useful for transplant root growth.

Health risks

In the 1990s, bone meal was identified as a vector for bovine spongiform encephalopathy
Bovine spongiform encephalopathy
Bovine spongiform encephalopathy , commonly known as mad-cow disease, is a fatal neurodegenerative disease in cattle that causes a spongy degeneration in the brain and spinal cord. BSE has a long incubation period, about 30 months to 8 years, usually affecting adult cattle at a peak age onset of...

 (BSE, or "mad cow disease") among livestock. It is believed by some that bone meal produced in the 1970s from the corpses of sheep bearing scrapie
Scrapie is a fatal, degenerative disease that affects the nervous systems of sheep and goats. It is one of several transmissible spongiform encephalopathies , which are related to bovine spongiform encephalopathy and chronic wasting disease of deer. Like other spongiform encephalopathies, scrapie...

caused BSE in cattle when it was fed to them, but the pathogen very rarely crosses species, so it is more likely to have spread from cow bone meal.
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