Soil microbes

Coming late to this discussion I'd just like to point out that the 
biodynamic preparations have shown to be an effective microbial input. 
 The 500 prep, made from cow dung and sprayed on pasture in spring and 
autumn is the best for large, general areas.  The others can be 
incorporated into any composting process and used on the soil or as 
foliar feeds.  John Reganold led a study in New Zealand comparing 
biodynamic and conventional neighbouring farms with identical soil 
profiles.  Microbial activity was one of the signficiant differences.  
The study was published in Science April 17 (?) 1993.