For quality control I send the castings off periodically to the #compost lab at ncstate for testing. There are target values for #vermicast lab analysis that I adhere to strictly. Most importantly are pH and C:N ratio. For vermicast, the limiting factors to optimal plant growth are salts, liming equivalencies, copper, and zinc. We get a reading on these factors also. I take composite samples from each batch of #castings, collecting from several locations and depths within the pile to make sure the sample is representative of the entire batch. Samples are labelled carefully in order to match up the lab report with the sample. I also want to say something about the fact that we wait a carefully allotted time - several months - before we even start the screening process. Castings that are “rushed” through are not really castings and don’t have all the #microorganisms present because not all of the material has processed through the worm. This is actually a much more important piec...