The sludge can be spread in a suitable bed. If you have a location that has been known to produce wild Morel mushrooms in the past , hell yeah - go for it. If you don't have such a location it is best if your prepare a suitable planting bed. A sandy soil with a modest amount of wood ash [not from treated wood] , wood chips and peat moss is best. A shaded and naturally moist but not water logged area is also advisable.
At the base of dead and decaying elm, sycamore or ash trees, if any are available is ideal. Your next step is to wait a few years and see what happens - be sure to inoculate multiple locations, as some will ultimately fail.
Another method, that is a tad more costly is using grow kits and mushroom spawn from reputable dealers. Mushroom Spawn is spores that have developed a little further to the point of being mycellium. The mycellium is usually infused into wood chips, sawdust, or grains and marketed as such.
Preparing a suitable morel bed
Any location you select should be shaded. Soil should be sandy adding some peat moss will help. Clay or rocky soils will not suffice . The soil should be moist but not saturated - it should be well draining. Ashes from non treated wood seem to be advantageous. Morel mushroom hunters have noted that Morels seem to pop up in areas that have had recent forest fires, perhaps due to the ash.
The regions best suited to grow Morel should be temperate climates, those that have all four seasons in moderation- not frigid and not balmy hot or tropical. Mix your spawn into the prepared suitable bed and cover with a layer of wood chips preferably chips from one of the trees they are known to favor - sycamore, ash, elm, poplar.
Although the mycellium may take hold rather rapidly, it shant produce any mushrooms for several years. With patience, perseverance and the help of the mushroom fairy you should have some Morels growing .... eventually.
A third slightly more involved method involves inoculating the actual trees where you want your Morel mushrooms to grow. Inoculating the tree roots with morel mycelia, is best. It can also be done with the slurry / sludge described earlier in this article.
Inoculation can done when planting saplings of suitable trees, when the roots are exposed. Saplings and young trees that that have been inoculated with morel spores/mycelia are sometimes available online also. If you don't plan to be planting any trees in the foreseeable future it can also be done by spreading the slurry near the base of the tree, although results are not as favorable.
I recently tried an experiment, dug around the roots of a poplar tree in the woods adjacent to my property and spread some slurry on them, don't know how this is going to turn out - I'll let you all know in a few years, assuming someone doesn't buy the property and build another darn house.
Digging up wild morel mushrooms for transplanting to your property has worked if you can find any. Be sure to harvest them with the soil and mycelium intact. The soil that hosted the wild morels should contain the elements your morel needs as it did host them in the wild. Be sure you can tell the difference between a true Morel and a false one. The false morels are at times toxic. See - How to Identify Morel Mushrooms
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