Bone meal
Bone meal is a mixture of finely and coarsely ground animal bones and slaughter-house waste products. It is used as a dietary supplement to supply calcium (Ca) and phosphorus (P) to monogastric livestock. As a slow-release organic fertilizer, it supplies P, Ca, and a small amount of N to plants. Uses. Dietary supplement. Bone meal, along with a variety of other meals, especially meat meal, is used as a dietary/mineral supplement for livestock. It is used to feed monogastric animals with bone meal from ruminants, however, it can contribute to the spread of bovine spongiform  encephalopathy (BSE) or "mad cow disease". Proper heat control can reduce salmonella contaminants. 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; for this reason, bone meal is no longer recommended as a calcium source. Fertilizer. Bone meal provides phosphorus and calcium to plants, along with a largely inconsequential amount of nitrogen. The N-P-K rating of bone meal is typically 3-15-0 along with a calcium content of around 12% (18% CaO equiv.), although it can  vary quite a bit depending on the source from 1-13-0 to 3-22-0. As bone meal is water-insoluble, it needs to be broken down before the plant can absorb it, either by soil acidity or by microbial activity producing acids. According to the Colorado State University, it can only be broken down in acidic soil (pH < 7.0) and releases its nutrients over a span of 1 to 4 months. History. The process was first suggested by Justus von Liebig (dissolving animal bones in sulphuric acid) around 1840 and first used in Britain by Rev James  Robertson in Ellon, Aberdeenshire in 1841. Before Liebig the expansion of agriculture had depleted the soil of essential nutrients. In desperation, farmers collected the bones from major battlefields like the Battle of Waterloo and the Battle of Austerlitz to crush them and refertilize the soil. In 19th century Europe, large scale production and international trade in bone meal was seen as essential for agricultural development.