In the early 1800’s, it was discovered that phosphate (P) is beneficial for plant growth. As the value of “pounded” bones were recognised as a P source, the demand grew quickly in the early 19th century. Unprocessed bones (hydroxyapatite; Ca5F(PO4)3OH) were crushed and applied to the soil at a rate of 1 t/A or more. In England, the demand for bones outstripped the domestic supply and by 1815, bones were imported from the Continent, reaching a maximum of 30,000 t/yr (Nelson, 1990). This led the famous plant nutritionist Justus von Liebig to complain:
“England is robbing all other countries for their fertility. Already in her eagerness for bones, she has turned up the great battlefields of Liepsic, and Waterloo, and of Crimea: already from the catacombs of Sicily she has carried away the skeletons of many successive generations. Annually she removes from the shores of other countries to her own the manuerial equivalent of three million and a half men…. Like a vampire she hangs from the neck of Europe” (Liebig).
The observation that not all bones were equally effective as a plant nutrient source led to experimentation to acidify the bones before adding them to the soil. One early innovator, John Lawes applied raw bone to his farm fields without seeing any additional crop growth. This led him to experiment with treating bones with sulphuric acid, which proved to be very effective. In 1842 he was granted a patent for “superphosphate of lime”, composed of calcium hydrogen phosphate and calcium sulfate. The manufacturing of superphosphate quickly spread around the world and marked the beginning of the modern fertiliser industry.
Phosphorus is the basis for all life on earth. It is the sixth most abundant element in living organisms, is a necessary constituent of DNA and our genetic code and provides the energy for all metabolic processes. Phosphorus is essential to global food security. The production of food, feed, fibre, and energy supporting population growth would not be possible without P. However, P lost from agriculture can cause problems with water quality resulting in eutrophication, and the raw material for making P fertiliser, rock phosphate, is a non-renewable resource. To ensure sustainability the recapture, re-use and circularity of nutrient resources essential. Thallo® our clean phosphorus and nutrient-rich fertiliser captures and re-uses this resource repeatedly and combined with its other elements has brought the early work by John Lawes into the 21st century.
Securing the nutritional needs for our increasing population will continue to drive a healthy demand for P. Innovation will continue to broaden our viable choices for P, which combined with social drivers, will continue to generate momentum towards a more closed P cycle. Further advances in plant breeding, agronomy, and fertiliser technology are required for today’s agricultural systems on soils with high P sorption capacity.
Today improved recovery of P that is directly consumed in human food and in animal feed will certainly gain more importance as P recycling from various waste streams is emphasised. Future efforts to more effectively reuse and recycle P derived from waste streams will likely include P sources that also favour root biology, sustain agricultural productivity, enhace environmental benefits and sustainability – we intend to be one of the leaders in this area.