No not at all. If you were going to add any "SOIL" I would only add a scoop of a previously composted amendment that contains "mycorrhiza" per the label. Otherwise just add dried mulched leaves :)
This post was edited by LoneCowboy on Fri, Feb 28, 14 at 14:48
We just had a discussion on this topic and a wide variety of opinions were expressed but no there is no reason to add soil to the compost material.
Once it was thought that putting good, rich soil on the material to be composted would add the bacteria that would digest that material. Today we know that all of the material we put into be composted already has the bacteria that will digest them in place, that is why the foods left out develop the fuzzy stuff on them.
Mycorrhiza refers to a relationship some fungi have with plants and not to any specific fungi. That relationship is most often symbiotic, mutually beneficial, in that the fungi get sugars from the plant in exchange to providing necessary nutrients to the plant. Mycorrhiza is not a specific fungi that you can add to soil or compost no matter what the sellers of products may tell you. Each plant develops this relationship with different fungi.
Yes, the addition of soil or clay to compost produces a superior product - higher CEC and better water retaining capacity. The addition of 5% to 10% soil or clay slurry will wet the material better than just water during composting and produces a compost with a better clay-crumb structure. This type of compost is sometimes referred to as humified compost.
Here is a link that might be useful: Humus Theories
I think some people are missing the word need in the OP's question.
The correct answer is no. You certainly may, but it is not needed.
I don't know how to link a thread, so I pulled up the recent discussion on this topic. Lots of info in the discussion.
I don't go far to put my compost into my garden beds, so I take advantage of the gophers' hard work and scoop up the mounds of clay soil I find that they have very nicely chewed up into a fine blend and add that to the compost!
It works out perfectly! Compost/soil added to the tops of the, beds, lightly tilled in , no worm kill that I can see!
But, for the most part, it's not necessary ! Nancy
Sir Albert Howards original Indore recipe for composting was 6 inches of vegetative waste, 2 inches of animal manure and 1/8 inch of good rich soil (to get the bacteria necessary to digest the material into the mix). Later research, in the 1950's, showed that the materials being composted already had the bacteria that would be digesting them and soil was not necessary to the composting process. Many of us found that to be true when we stopped adding soil to our compost piles and the digestion process worked just as well without that soil.
If someone likes the extra work involved in digging soil up to add to the compost pile they can do that, as long as they understand it will do little for the process.
Only soil added to my compost is when I add weeds that I pulled. Sometimes some soil hangs on to the roots.
But I don't actively add soil to my pile.