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Re: Proper compost

The definition of properly composted material, when applied to thermal compost, is that it has reached temperature throughout the material for long enough that weed seed, human pathogens and most of the plant pathogens and pests have been killed.  There should be no E. coli in properly composted material. 

If someone SAYS material was properly composted, and the material has E. coli in it, then it is not properly composted material.  Simple logic.

Most people mean a compost is finished if it has heated and come back down to ambient temperature.  Does that guarantee that appropriate temperatures were reached, for long enough, through the whole pile?   Long enough to kill the E. coli and other human pathogens?

It should mean that.  But if people are calling a compost finished, and the compost still has E. coli in it, then the compost was not truly finished.  It's still just partially decomposed organic matter. 

Because organic matter stands in a pile and heats a bit, does that make it compost?   No.  Did the composting process get started?  Yes, but it was not allowed to finish.  If you leave organic matter in a pile long enough, will it become compost?  Sure, but when do you know when it is "finished"? 

There are standards.  Excuses that because it's too expensive to turn, or monitor, or aerate organic matter properly, and so not remove E. coli fully, does not mean it's ok to call the material compost.  Because people are not willing to do a proper job, does not mean that we change the definition of compost. 

Could there be categories of quality in compost?  Yes.  Especially if composting operations are not doing what is necessary to produce compost that is completely and correctly processed. 

Data showing the amount of E. coli in compost should be necessary, along with other chemical and biological properties, to document compost quality. 

Implementation of standards remains to be seen.  But because someone calls something good compost does not mean that it is so.  Data are required.  Properly composted material does not contain E. coli.

Does this mean most of the commercially-sold "compost" produced in the US is not properly composted?   Yes, that's what it means.  Doesn't change the definition of properly composted material, however.

Elaine Ingham
President, Soil Foodweb Inc.