Phosphogypsum Stack Reclamation Using Soil Amendments and Short-Rotational Woody Species

Abstract

Phosphogypsum (PG) is a by-product of phosphorus fertilizer production that is stored in large piles (stacks). Typically, PG stack reclamation focuses on topsoil caps vegetated with grass which has limited economic return. Therefore, a study was conducted using the short-rotational tree species (Picea glauca, Populus balsamifera) to determine their potential in PG stack reclamation. Five soil amendments (compost, compost with mycorrhizal fungi, manure pellets, black earth, mycorrhizal fungi) with a control (no amendment on PG) were used in a field experiment to determine whether they would enhance the growth of the planted species. After two years, amendments had little effect on the height, diameter or biomass of either species. P. balsamifera on PG (control) was significantly healthier than in amended soils. The healthiest and most successful trees for both species were found in the control treatment. Organic amendments (compost, manure) had significantly higher nitrate and phosphorus than most of the other treatments. Black earth and mycorrhizal fungi did not affect any soil properties relative to the control. This study suggests short-rotational forestry plantations of Populus balsamifera appear to be meeting reclamation objectives for PG stacks, similar to traditional grass covers; however, the built soil profile could limit tree success in future.