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Phosphorus availability from the solid fraction of pig slurry is altered by composting or thermal treatment
- Christel, Wibke, Bruun, Sander, Magid, Jakob, Jensen, Lars Stoumann
- Bioresource technology 2014 v.169 pp. 543-551
- combustion, composting, drying, heat treatment, phosphorus, phosphorus fertilizers, pig manure, pyrolysis, temperate soils, temporal variation
- 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 16weeks. 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.