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Authors
Advisor(s)
Abstract(s)
The use of animal slurry in modern agricultural systems is receiving considerable attention, mainly due to the
latest increase in chemical fertilizer prices. However, the use of raw animal slurry to fertilize horticultural crops
can, on the one hand, lead to significant ammonia emissions and, on the other hand, be an important source of
zoonotic pathogens. Therefore, proper treatment is required. The present study explored the modification of the
pH value of pig slurry using by-products from different agro-industrial activities as a strategy to control these two
problems. Three approaches were used, namely acidification and biological acidification (bio-acidification) to pH
5 and alkalization to pH 9.5. The most promising of the 14 different additives and additive combinations initially
considered should be able to reach the target pH at a dose of less than 20% (m/m). The presence of Salmonella
and the number of Escherichia coli colony forming units (CFU) were evaluated in the slurry for each selected
treatment. To ensure that treated slurry remains of interest as an organic fertilizer, the impact of treated slurry on
plant germination and nitrogen (N) availability was also assessed. The by-products from the brewing and yeast
industry failed to reduce the pH to 5. In fact, the bio-acidification of pig slurry was only possible with additives
rich in carbon. Although slurry sanitization (<1000 CFU E.coli g 1 slurry) was not guaranteed by all treatments, a
reduction in E.coli numbers was observed with all additives. The ammonium content of the treated slurry was
significantly reduced (up to 20%) with treatments involving bio-acidification. N mineralization was evidenced
for all additives used for slurry alkalinization but no N mineralization was observed when using acidification
with H2SO4 or by-product spent acid. The phytotoxicity bioassay showed that most additives do not have a
negative impact on germination. The results presented here suggest that agro-industrial by-products are capable
of modifying the pH of pig slurry. Depending on the pH modification strategy and additive used, treated slurry
may be safer and of higher fertilizing value than untreated (raw) slurry.
Description
Keywords
Pig slurry Bio-based fertilizers pH modification Slurry sanitization Potential N mineralization Phytotoxicity
Pedagogical Context
Citation
Chrysanthopoulos, Stamatis, et al. “Agro-Industrial by-Products as Alternative Additives for the Agronomic Valorization of Pig Slurry through pH Modification.” Journal of Cleaner Production, vol. 434, Jan. 2024, p. 140052
Publisher
Elsevier