Analysis of Phosphorus Extraction from Spent Mushroom Compost Application on Reclaimed Mine Soils

Open Access
Groff, Serena Joy
Area of Honors:
Environmental Resource Management
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Richard Charles Stehouwer, Thesis Supervisor
  • Robert David Shannon, Honors Advisor
  • phosphorus
  • mine soils
  • abandoned mine soils
  • mushroom compost
  • amendment
  • reclamation
  • soil fertility
  • nutrient
  • adsorption
Abandoned mined lands are often regarded as infertile zones with limited agricultural potential. However, reclamation with organic materials has been shown to greatly increase biomass crop production on such sites. In Pennsylvania, mushroom industries are looking for an efficient way to handle spent mushroom compost (SMC). Applying SMC to mine soil increases fertility, but also introduces an environmental concern due to high levels of phosphorus (P). Therefore, the fate of P applied from SMC needs to be understood to a greater extent. This laboratory study investigated P loss from surface-applied SMC and its subsequent transport through mine soils. Mine soils amended with manure + paper mill sludge or lime + fertilizer were obtained from a site in Schuylkill County, either with no added SMC or 15 ton/acre repeated applications. A mechanical vacuum extractor was utilized to simulate a 5-year precipitation event so that leachates could be collected after passing through two 5-cm soil layers and P movement could be measured. Colorimetric analysis by an automatic Lachat allowed orthophosphate fractions to be identified, whereas an ICP analysis machine was used to determine total P. By subtracting ortho-P from the total, organic P fractions were obtained. The orthophosphate fraction accounted for about 75% of each leachate. It was found that the spent mushroom compost layer leached approximately 59.7 mg total P/g compost. Repeated applications of SMC increased the amount of P sorption on manure + paper mill sludge reclaimed soils when compared to the reclaimed soils without SMC application. In both treated soils, the amount of P leached below 5-cm was minor in the context of environmental concerns. For all simulations, the subsoil layer effectively immobilized the remaining P. This study shows that P was retained despite previous applications of SMC. Once future studies answer questions about the impacts of other variables on field application of SMC, mushroom industries can begin to efficiently handle their waste product.