November 28, 2016
They’ve mixed phosphogypsum – a gypsum powder created from producing fertilizer out of phosphate rock – with topsoil, spread the mixture on a former cooling pond at the site and seeded various types of vegetation in the material.
Agrium had been testing native grass species on the pond quite successfully, so teams initiated a tree demonstration at the site last summer, with help from forestry experts.
Close to 1,000 trees – four different varieties of willow and hybrid poplar – were planted, and the results were remarkable. The trees grew on the phosphogypsum/topsoil mix just as well as they would on unaltered agricultural land, if not better.
Phosphogypsum is stored in large piles called gypstacks. Agrium produces phosphate fertilizer at its facilities in Redwater, Alberta and Soda Springs, Idaho, but over 80 countries around the world have gypstacks. Many countries reuse this byproduct gypsum in construction and agriculture, but in North America the phosphogypsum is rarely reused and gypstacks must thus be eventually reclaimed.
Agrium has taken on the responsibility of collaborating with community partners and government officials to research methods to determine the best way to reclaim the land once production has ceased.
Typically, gypstack reclamation involves contouring the piles, covering them with soil and seeding them to a grass mixture. Establishing a forest on a rehabilitated gypstack is a new idea and has many potential benefits, including:
- carbon sequestration
- biomass production for green energy or wood chips
- improved esthetics
- reduced on-site maintenance
- increased ecosystem diversity and long-term sustainability