Phosphorus availability from the solid fraction of pig slurry is altered by composting or thermal treatment

Bioresour Technol. 2014 Oct:169:543-551. doi: 10.1016/j.biortech.2014.07.030. Epub 2014 Jul 12.

Abstract

The alteration of easily available phosphorus (P) from the separated solid fraction of pig slurry by composting and thermal processing (pyrolysis or combustion at 300-1000 °C) was investigated by water and acidic extractions and the diffusive gradients in thin films (DGT) technique. Temporal changes in P availability were monitored by repeated DGT application in three amended temperate soils over 16 weeks. P availability was found to decrease in the order: drying>composting>pyrolysis>combustion with increasing degree of processing. Water extractions suggested that no P would be available after pyrolysis above 700 °C or combustion above 400 °C, respectively, but during soil incubation, even char and ash, processed at 800 °C, increased P availability. Low-temperature pyrolysis vs. combustion was found to favor P availability as did application to acidic vs. neutral soil. Composting and thermal treatment produced a slow-release P fertilizer, with P availability being governed by abiotic and biotic mechanisms.

Keywords: Combustion; Diffusive gradients in thin films (DGT); Digestate compost; Manure char; Slow pyrolysis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biodegradation, Environmental
  • Carbon / analysis
  • Charcoal / chemistry
  • Chemical Fractionation
  • Diffusion
  • Hydrogen-Ion Concentration
  • Nitrogen / analysis
  • Phosphorus / isolation & purification*
  • Sewage / chemistry*
  • Soil / chemistry*
  • Sus scrofa
  • Temperature*
  • Time Factors

Substances

  • Sewage
  • Soil
  • biochar
  • Charcoal
  • Phosphorus
  • Carbon
  • Nitrogen