New research suggests thermally treated sewage sludge from wastewater treatment plants could replace commercial fertilizers. Photo by Kekyalyaynen/Shutterstock

ANTANANARIVO, Madagascar, Aug. 15 (UPI) -- A new study suggests sewage sludge could serve as a sustainable and effective plant fertilizer.

Phosphorous is essential to the diets of both plants and animals. In commercial agriculture, fertilizer ensures crops get enough of the vital nutrient.


The production of commercial fertilizers requires a lot of energy. Thermally treated sewage could serve as a sustainable substitute, researchers say.

When scientists fertilized ryegrass plots with thermally treated sewage and commercial triple superphosphate fertilizer, they measured comparable soil and plant benefits. Thermally treated sewage encouraged improved shoot growth and suggested the potential for greater root development.

Though commercial fertilizer allowed for more uptake of phosphorous, the diversity of nutrients in the sewage sludge encouraged microbial activity that immobilized phosphorous. Thus, phosphorous that wasn't immediately absorbed by plant roots remained in the soil for later use.

"It was shown to have a higher agronomic effectiveness in comparison with commercial fertilizer," Andry Andriamananjara, a researcher at the University of Antananarivo in Madagascar, explained in a news release.

The research was published in the journal Frontiers in Nutrition.

"Although on the short term it enhanced the microbial biomass and therefore phosphorus immobilization, on the longer term the phosphorus captured by this microbial biomass can again become available for the plants," Andriamananjara said. "Moreover, sewage sludge is a non-limited continuously available and sustainable fertilizer source."