So what is mushroom soil? In our area it is probably a mix of horse manure and used bedding straw. That is first composted by the farmer to raise the temperature and break it down a bit. Then it is steam sterilized, spread in mushroom houses, and inoculated with mushroom spawn. The mushrooms feed on the organics in the mushroom compost, grow to maturity, and are harvested. The soil is then known as "spent mushroom compost" and is sterilized once again before being removed for disposal from the mushroom house. Weed free from the composting and steaming procedures. The mushroom soil (2-1-1, ph 6.8) is then used as an organic fertilizer or soil amender. I was surprised at how weak those fertilizer numbers are, so a great part of the value is in the organic roughage that it adds to soil.
A couple of the long time gardeners and mushroom soil buyers at the park were recently contacted by the farmer who has been selling the soil. Apparently it is easier to sell mushrooms to eat, than it is to sell mushroom soil to garden. He needed to get in a new crop of mushrooms in the houses, and had no place to get rid of the spent mushroom soil in the houses. If the park could take 30 to 50 truckloads, he would deliver it for FREE. As in totally free!!! But it had to be that many, or nothing doing.
Thus began the negotiations with the park manager about where we could put this free bounty. Some gardens on the edges could take deliveries directly, but the bulk of it would go along the side by the park compost piles, mostly out of sight from the public. The next problem was the wet soil at the park from summer and fall rains creating the possibility of the truck getting stuck. So after a stretch of decent weather, the mushroom truck started dropping its treasure.
So now when I go to the park I usually take my pitch fork and 20 gallon tupperware containers. A full container is quite heavy as the soil currently has a high water content. I can move a container into my wagon or a wheel barrow, but certainly can not carry one any distance. It is thus a tedious procedure to haul the stuff to my interior garden, where I then painstakingly apply it around plants, trowel by trowel. It does look pretty on the garden, and I do expect an explosion of growth in the fall garden.
Update: 10/24/11 Yesterday I arrived at the park at about 8:00 AM to load some wood chips to augment the path areas. I was surprised to see the big mushroom truck there already. With his dumper elevated but nothing else happening. I forked three containers of chips, and still nothing happening with the truck. I saw movement in the cab and concluded the driver was having a smoke or a chat on his cell phone. I went over to the mushroom pile near my garden to get a container of that black gold. Still no truck movement. As I left the park, I stopped to chat with the gate attendant, Jay. Jay's comment, "See your buddy, the mushroom soil guy, got stuck." Ah, mystery solved. Will they quit deliveries now?