I would check it's ph before adding liberally. It may be fine, but I remember on a post in the past that lime is sometimes added to mushroom compost and horse manure. It 's better safe than sorry.

There is a lot of misinformation out there about spent mushroom compost, such as that lime is added. Since the pH of SMC is about 6.8 adding lime would be a waste of money, something commercial people are not too apt to do.
Last time I looked at the price of SMC and manure they were comparable.

Here is a link that might be useful: About Spent Mushroom Compost

It seems as if you are "lasagna gardening", or just using the raised bed to compost in until spring comes? At that note, decomposition can sometimes tie up nitrogen and can have other adverse affects like poor plant growth the first year or so while the compost is decomposing. Its that reason, I try to have compost piles for composted, and raised beds for growing. I also wouldn't add bread, just plant waste..

I do, mulch my garden heavily with leaves mixed with grass clippings and other plant waste, so you could consider this composting. But, it's important to note, it's more of a mulch, it's not the right ratio to heat up and create nitrogen tie up problems,etc.. The leaves/grass clippings as a mulch stays in contact with air, so they will not pull nitrogen out of your soil, which halts plant growth, it can get the nitrogen from being exposed to air..

I would find good compost/soil(mushroom or not), fill the raised bed with compost, mulch with a couple inches of plant matter, your good to go.

I would remove all the uncomposted bread and other stuff and make a seperate compost pile, don't add bread, meat, dairy next time. Remove all the ubcomposted material, fill the raised bed with quality composted material, after the raised bed is filled with compost/soil, mulch with a thick later of plant material like leaves or grass clippings. Note: the reason i mix my leaf mulch with grass clippings is to speed up decomposition. But it is not so quick to heat the mulch. You want efficient decomposition with minor disadvantages, nitrogen tieup, etc..

This post was edited by Natures_Nature on Mon, Feb 17, 14 at 11:36

Assuming this stuff is fully composted, it's compost and does not need to be added to a compost pile. I'd put it directly into the soil, now or store it until spring.

Why not compost bread? That's another myth. Meat and dairy almost everyone agrees with, but no reason not to add baked goods, in my opinion.

Thanks to all. I'll store it.

Make sure the compost can breath, it needs plenty of oxygen or it will ruin.. Make sure you keep the lid off the container, and try to use a container that can breath...

Natures_Nature, it's in plastic bags. I put them under a shed.

Maybe I need to poke a hole in the bags so it can breath? Or open the bags and put in barrels with holes?

It is leftovers from last year, that is why it is so cheap. I opened one and it still smells earthy.

the mushroom compost from a big operation near me is high in potassium salts. I had a lot of white salts showing up on the top my soil. A little is probably ok, but I won't be using it again. Of course the manure around here is almost entirely ruined by grazon herbicide and poor animal management.

Poking holes in those bags may allow the Spent Mushroom Compost to "breath" and will allow moisture in that will allow the bacteria to become active and digest that compost so possibly it will be gone if stored long enough. There is no real good reason to store that compost for any length of time.
Spent Mushroom Compost high in Potassium Salts, what ever that is, would not grow mushrooms and would therefore be useless for what is was mixed for.

Here is a link that might be useful: About salts

This post was edited by kimmsr on Thu, Feb 20, 14 at 7:06

I used to be under the impression that mushroom compost had to be excellent, sort of like the manure based composts I had made and used for 25 years in my greenhouse and nursery work. I am not a chemist and do not do soil sampling anymore. I do know what salts are and how high EC levels are damaging to plants When I used up to 1/4 of spent mushroom compost in my potting mix, plants did poorly and salts appeared. In addition our county agent in the local paper described the spent mushroom compost locally available as having high levels of potassium salts...he does have access to high quality soil analyses. Maybe they're using lots of potassium nitrate to feed the mushrooms...I don't know about that. Go ahead and punch holes in the bags if you like. I haul my soil amendments in the pick-up and do the best I can with local available ingredients...minus the peat moss and perlite I can't seem to replace.