From mmiller@pcsia.com Sat Mar 11 19:56:49 2000 Date: Sat, 11 Mar 2000 10:27:39 -0600 From: mmiller@pcsia.com To: sanet-mg@ces.ncsu.edu Subject: manure usage on certified organic farms Here is some background information by Russ Bullock from when this topic was discussed last September. Mike Miller "Enteric bacteria (from the Family Enterobacteraceae, including Enterobacter, Shigella, Escherichia, and Salmonella species) are found in soils amended with both organic and synthetic fertility amendments (research that I have been involved with show that on average, after amendment of soil with organic amendments such as cattle manure, swine manure, and different kinds of composts, a spike of enteric bacteria occurs, with between 1*10 to log 6.4-8.1, or more than 1000000 to 100000000 colony forming units, CFU, per gram of soil occurring in soils). Often populations will decline over time in soils amended with organic amendments, while increasing in soils amended with synthetic fertilizers, and over studies have found no significant difference over time in soils regardless of amendment type (1*10 to log 7.2-7.4 CFU's per gram soil). The major point I want to make is that even in soils _never_ (to my knowledge, and one study was conducted on experimental research stations) amended with organic amendments enteric bacteria are _Always_ present. The major question is whether the populations present are pathogenic to people. For the most part, the answer must be no. If pathogenic enteric bacteria were always present in soil, and since most soils (regardless of fertilizer type used) contain enteric bacteria, more food-borne illnesses (on fresh vegetables and fruit) would be attributed to them. Pathogenic enteric bacteria are accustomed (and thrive) in the gut of vertebrates (both warm- and cold-blooded organisms), usually with temps at 37 degrees C (for mammalian pathogens), and an abundant food source. The soil is an oligotrophic environment of highly variable temps and food availability, rarely meeting the optima for growth and development needed for our pathogenic friends. Any organic amendment (regardless of composting, although composted organic amendments have many advantages over uncomposted manures, not the least of which is smell) that is incorporated into the soil and left alone until harvest (2 to 3 months for most vegetables, longer for other crops) few if any pathogenic enteric bacteria will likely remain." To Unsubscribe: Email majordomo@ces.ncsu.edu with the command "unsubscribe sanet-mg". If you receive the digest format, use the command "unsubscribe sanet-mg-digest". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". All messages to sanet-mg are archived at: http://www.sare.org/san/htdocs/hypermail