From jgruv@wam.umd.eduSun Jul 14 00:58:40 1996 Date: Sat, 13 Jul 1996 11:56:53 -0400 (EDT) From: joel b gruver To: sanet-mg@amani.ces.ncsu.edu Subject: effects of fertilization on microbial ecology/ N budget of vermicomposting Hello to all, I am currently reading through the Proceedings of the 9th international symposium on Soil Biology and Conservation of the Biosphere. (ed.) J.Szegi I have 2 questions. One article by a Russian scientist discusses the effects of fertilization on microbial ecology. It suggests that high levels of fertilization promote the growth of"toxigenic" microorganisms. At a certain threshold which is very high for Mollisolls but much lower for Spodisolls fertilization causes crop yield reduction due to the phytotoxicity of microbial products. The organisms mentioned are mainly fungi in the Penicillum and Asperigillus genera. Is any familiar with this phenomena ? A second article discusses N fixation in the gut of earthworms and presents that the vermicomposting systems studied produced 40%+ N in excess of the N content of the organic materials fed to the earthworms. The worm species was E. eugeniae and the substrate was Paspalum dilitatum grass. Is it generally recognized that earthworms host substantial amounts of N -fixation ? Joel Gruver U of MD, Agronomy