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New Research Reports Ability of Sewage Sludge to Form Sustainable Fertilizer

Researchers from University of Antananarivo, Madagascar suggested that thermally conditioned sewage sludge can be altered into fertilizer to improve soil properties.

A research led by Andry Andriamananjara from the University of Antananarivo suggested use of thermally conditioned sewage sludge as an excellent fertilizer to improve soil properties. The research was published in the open-access journal Frontiers in Nutrition on June 16, 2018.

Phosphorus is a key nutrient for all living beings and its deficiency leads to a disorder known as hypophosphatemia in humans. The deficiency is responsible for diseases such as rickets in children and osteomalacia in adults. In crops, the deficiency reduces the crop productivity.  There is a strong need for increased recycling to ensure phosphorus security, as the source of phosphorus is non-renewable phosphate rocks.  Moreover, efficient use and reduced environmental dissemination of phosphorus is needed to secure the ability to feed a growing population.

Now, researchers from University of Antananarivo suggested that phosphorous is a readily available alternative to commercial fertilizers in agriculture due to increased phosphorus content of sewage sludge. A phosphorus radiotracer technique was used by the team to measure the availability of phosphorus for plants in thermally conditioned sewage sludge. Pots filled with soil were used to grow ryegrass. The pots were labeled with isotopic Phosphorous and thermally conditioned sewage sludge as fertilizer was used. The phosphorous intake of shoot and roots was analyzed along with measurements of radioactivity. The researchers observed increased shoot biomass and increased phosphorus uptake as the plants increased the ability to exploit soil nutrients. However, the total phosphorus uptake from commercial fertilizer was higher than thermally conditioned sewage sludge. Water-soluble commercial fertilizer contain phosphorus that is immediately available for plant uptake. However, thermally conditioned sewage sludge offers phosphorous in a lower available form as microbial activity in the sludge induce competition between microorganisms and the plant roots for phosphorus uptake.