FAYETTEVILLE, Ark. – The United States could exhaust its domestic phosphorus supply within 40 years. Europe, Latin America and Southeast Asia already depend on imports from China and Morocco to meet their needs. Without phosphorus, crops cannot grow — and without a reliable supply of the mineral, the world’s food supply is at risk.

“You talk to any farmer and they know the ‘NPK.’ The nitrogen, phosphorus and potassium, so NPK, are the three big ones that we typically have to add to make sure we have enough to grow crops,” said Becca Muenich, an associate professor of biological and agricultural engineering at the University of Arkansas. The chemical symbol for potassium is K.