Upgrading of the Solid Fraction of Pig Slurry as Phosphorus Fertilizer: The Impact of Biological and Thermal Processing on P Availability

Research output: Book/ReportPh.D. thesisResearch

  • Wibke Christel
Improved recycling of the solid fraction of separated pig slurry, which is considerably enriched in the essential plant nutrient phosphorus (P), could balance the P input in differently used agricultural areas and reduce the unsustainable depletion of the limited P rock reserves. By subsequent biological or thermal treatment, the P concentration of the pig slurry-derived products is furthermore increased, but these processes are also expected to affect P availability from the respective products. Consequently it was the overall objective of this PhD project to identify options for upgrading the pig slurry solid fraction as well as investigating their impact on the applicability of the product as P fertilizer. Special attention was moreover given to the effect of the soil properties on the development of P availability over time.

In conclusion, both biological and thermal processing of pig slurry solids reduced P availability in the initial phase after soil amendment. Only the solid fraction, had a high initial P availability, which was within the same range as mineral P fertilizer, but P availability decreased significantly within one growing season, whereas the thermally processed materials had a more constant P availability. Due to a significant enrichment of P and considerable reduction in volume, manure-derived char or ash could easily be stored and transported to P-deficient agricultural areas, where it could be applied as slow-release P fertilizer.
Original languageEnglish
PublisherDepartment of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen
Number of pages185
Publication statusPublished - 2014

ID: 123836083