Reuse Phosphorus on Farmland

The important nutrient for potatoes can be reclaimed from wastewater in the form of struvite

By Soil Science Society of America

Phosphorus is one of the main ingredients for healthy plant growth. Plants get phosphorus from the soil, and much of it is applied to farm fields in the form of fertilizers.

The major current source of phosphorus, which comes from rock, is running out. Plus, it must be mined and then chemically converted and transported long distances. This costs money and uses valuable resources. The Soil Science Society of America’s (SSSA) February 15, 2022, “Soils Matter” blog took a look at research that is making a circular phosphorus cycle through struvite reclamation. Bloggers Kristofor R. Brye, University of Arkansas, and Lauren Greenlee, Pennsylvania State University, wrote about their research into reclaiming phosphorus, in the form of struvite, from wastewater treatment plants. Their research is looking at alternative ways to retrieve phosphorus, such as in the form of struvite. Struvite is a chemical

Above: Electrochemically precipitated struvite is applied to the surface of soil in eastern Arkansas for a corn study, in 2020. Struvite slowly dissolves in the soil, which may reduce nutrient losses in runoff and help the crops grow. Photo courtesy of Niyi Omidire

Left: Reusing phosphorus from wastewater treatment plants creates a cycle. Crops are grown on farms, sold in markets, and eaten. Wastewater treatment plants recover valuable phosphorus, which is then applied back onto the farm. Photo courtesy of staff members from the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America compound that contains not only phosphorus, but magnesium and other elements like nitrogen. All of these are important nutrients for crops.

Struvite has shown promise for use in agriculture as an alternative fertilizer-phosphorus source. Both greenhouse and row-crop studies suggest that struvite is a viable fertilizer compound compared to traditional fertilizers.

Wastewater treatment plants work to purify water so that it can be reused. They fall under strict standards from the Environmental Protection Agency.

LARGE-SCALE EXTRACTION

Struvite can precipitate from wastewater in similar ways to rock candy formation. Scientists have found that it is not only possible to pull struvite from wastewater, but that it can be done on a large scale.

Brye and Greenlee’s teams used both chemical and electrochemical