The goals of the present study were to evaluate the suppressive capability of anaerobicall y digested slurry
(ADS) against Phytophthora capsici and to determine the key factors of disease control in ADS. This was
achieved by the investigations of the changes in microbial populations and the levels of antimicrobial
comp ound during anaerobic digestion (AD). AD had no significant impact on the numbers of antag onistic
fluorescent pseudomonads or Bacillus sp. The contents of total phenolics, volatile fatty acids and sugar fed
with the raw slurries to the reactors were decreased by AD. However, the bioreactor effluents had higher
concentrations of humic substanc es and ammonia than the feedstocks. Moreover, AD had a different
influence on the content of amino acid in the pig manure compared to the dairy manure. The results
obtained indicated that the key inhibitory factors of ADS might be attrib uted to ammonia and humic
substances