University of Illinois researchers have shown a substance separated from wastewater holds promise as a “triple win” for phosphorus (P) use in farming. Struvite can substitute for popular P fertilizers, while at the same time reduce P runoff from farm fields and possibly boost nutrient uptake in crop plants

We visited recently with Andrew Margenot, the leader of field-scale trials testing magnesium monoammonium phosphate (MAP), a known fertilizer since its discovery in European medieval sewage waste sites in the 1850s. He says the compound was labeled struvite at that time, but it’s only recently gained traction as a possible substitute for MAP and DAP.

The Illinois study covered 14 field trials in plots ranging from 1,000 square feet to 2 acres. Results indicates struvite may benefit growers and environmentalists if it were to become a commercially viable fertilizer. 

“We found struvite can be a drop-in substitute for MAP and DAP in soybean production, showing no yield drag over the popular P sources,” Margenot says. “In fields with soils low in magnesium, it showed a bump in yields.”

Margenot says struvite is an insoluble, crystalline structure filtered out of wastewater treatment facilities, which reduces the P content of treated water.

“Since MAP and DAP also contain nitrogen, the use of nutrient-stable struvite could reduce field runoff problems and nitrogen (N) loss through leaching,” he says. “With fall-applied anhydrous ammonia applications, we knife in the N source with stabilizers to keep in place, but we don’t do that with MAP and DAP.”