Anaerobically digested poultry slaughterhouse wastes as fertiliser in agriculture

Chemical and physical analysis, 27-d plant growth assays with carrot (Daucu s carota) and Chinese cabbage (Brassica campestris var, chinensis), and 5-d phytotoxicity assays with Chinese cabbage and perennial ryegrass (Lolium p erenne) were used to investigate the suitability of anaerobically digested poultry slaughterhouse waste for fertiliser in agriculture and the effect o f aerobic posttreatment on the properties of the digested material. The digested material appeared to be rich in nitrogen. In 27-d assays with digested material as nitrogen source, carrots grew almost as well as those fertilised with a commercial mineral fertiliser used as reference, whereas, the growth of Chinese cabbage was inhibited. In further 5-d phytotoxicity assays, the digested material inhibited the germination and root growth of ryegrass and Chinese cabbage, apparently because of organic acids present i n it. Aerobic post-treatment of the material reduced its phytotoxicity but, probably due to the volatilisation of ammonia, resulted in loss of nitroge n. (C) 2001 Published by Elsevier Science Ltd.