The search for a sustainable slow-release fertilizer—a key to sustaining global food production at a time of burgeoning population growth—has led Chinese scientists to an ingredient used in some diarrhea medicines. They describe use of the substance, attapulgite, as a “carrier” for plant nutrients in a report in American Chemical Society’s journal Industrial & Engineering Chemistry Research.

One of the lead researchers, Boli Ni, contends that about half of the 150 million tons of fertilizer used worldwide every year goes to waste. That’s because most fertilizers release nutrients too fast for the crops to use. The rest can run off farm fields and create water pollution problems. Existing slow-release fertilizers have drawbacks, which Ni was not quoted as explaining.

Ni’s team turned to the environmentally friendly substance attapulgite, an inexpensive, nutrient-rich clay used for decades to treat diarrhea and for other applications. It once was an ingredient in Kaopectate marketed in the United States. They also included guar gum, used in cosmetics and to thicken foods, and humic acid from decayed plant material.

The Chinese report describes development and successful tests of a new pelleted fertilizer composed of those three ingredients. The slow-release pellets were easy to prepare, reduced nutrient loss via runoff and leaching, improved soil moisture content and regulated soil acidity and alkalinity, according to the researchers.

“All of the results indicate that it (the fertilizer) may be expected to have wide applications for sustainable development of modern agriculture,” Ni is quoted as saying.

The fertilizer product granules have a clay matrix, guar gum inner coating and guar gum-g-poly/humic acid superabsorbent polymer outer coating. Granules reportedly have consistent size of 2 to 3 millimeters, are low moisture and provide high mechanical hardness.

Per the research published abstract, “The experimental data and analysis in this study indicated that the product prepared by a simple route can effectively reduce nutrient loss in runoff or leaching, improve soil moisture content and regulate soil acidity and alkalinity levels.”

The authors noted funding came from the Ministry of Education in China and Gansu Province Project of Science and Technologies. No private industry funding was acknowledged.