Researchers have uncovered new insights into how phosphorus from recycled materials moves through soil—offering guidance to support more sustainable fertilizer use.
Phosphorus is an essential nutrient for plant growth, yet many soils lack enough of it to support strong crop yields. Farmers often rely on fertilizers made from mined phosphorus, a limited, non-renewable resource.
As global agriculture shifts toward more sustainable practices, researchers are exploring alternative fertilizer recipes made from waste materials. These “recycled” ingredients include sewage sludge (leftover solids from water treatment), sewage sludge ash (from when those leftovers are burned), and meat and bone meal (bones and tissues that are not consumed).
In a recently published study, researchers from Denmark, Brazil, Germany, Lithuania, and Switzerland used the Canadian Light Source (CLS) at the University of Saskatchewan to examine how phosphorus from these recycled fertilizers behaves in different soils over time. The goal was to better understand when and where this phosphorus becomes available to plants—critical information for improving its effectiveness in agricultural settings.
The researchers used the CLS to identify the chemical forms and precise amounts of phosphorus present in both the fertilizers and soils.
“Phosphorus is one of the most difficult elements in the soil to analyze in a conventional lab,” says Aimée Schryer, lead author of the study and postdoctoral researcher at the University of Copenhagen. “It’s hard to make reliable conclusions or recommendations that you can use in the field based on those results; it’s more of a guess.”
“That’s why using the synchrotron was so helpful. It allowed us to discover exactly what's within our soils and within these recycled fertilizers so that we're much more confident with our conclusions.”
The team found recycled phosphorus behaves differently than conventional mineral fertilizers. While mineral phosphorus typically becomes less available over time, some recycled sources—particularly those derived from sewage sludge—became more available with time and moved further through the soil as time passed.
Click here to see more...