Researchers from the Ministry of Education in China have discovered a sustainable slow-release fertiliser in an ingredient commonly found in diarrhoea medicines.   

The substance, attapulgite, is described as a "carrier" for plant nutrients in a report in ACS' journal Industrial & Engineering Chemistry Research.

Boli Ni and colleagues explained that about half of the 150 million tons of fertiliser used worldwide every year goes to waste, as most fertilisers release nutrients too fast for the crops to use. This creates problems of run-off, which leads to pollution, necessitating a new approach to fertiliser development.

Existing slow-release fertilisers have drawbacks, which Ni's team claim is not the case with attapulgite, an inexpensive, nutrient-rich clay used for decades to treat diarrhoea as well as in other medical preparations.

The substance is being mined commercially by two companies, including BASF chemicals. It is an example of Fuller's earth; a group of highly plastic, sedimentary clays.

Working with colleagues from the American Chemical Society, Ni’s team released a report which describes the development and successful tests of a new fertiliser made using attapulgite, guar gum, used in cosmetics and to thicken foods, and humic acid from decayed plant material.

The team found slow-release pellets made using the three ingredients were easy to prepare, reduced nutrient loss via runoff and leaching, improved soil moisture content and regulated soil acidity and alkalinity.

Ni commented, "All of the results indicate that it may be expected to have wide applications for sustainable development of modern agriculture."

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