Be it cakes or grain spawn, it should be 100% colonized. Gently pack the jars in a super thick construction trash bag or something similar to transport them to their new home. DO NOT open the jars until they are ready to be broken up and dropped into the substrate. The less exposure to the outside world the better. #2 Place your unpasteurized horse poo in a doubled Rubbermaid bin or a large stock pot
Using a bin inside a bin helps with the weight of the water. It also helps hold in the heat, but it mainly helps the walls remain solid versus bending outward and possibly cracking under the pressure.
#3 Hydrate the straw or manure in the container with water that has been heated to 145F-165F. Tap water is usually 120-160 depending, so starting out with hot tap water is a good start. allow the water to naturally drops back down to 80F (usually takes about 6-8 hours), then strain with a mesh bag or pillow case. Don't worry about field capacity when straining, that can be adjusted by squeezing it out by hand when creating the patch & mixing spawn.
Dry materials are easier to transport, but honestly I like to soak my straw or manure in a pot or Rubbermaid bin so that it is pasteurized, eliminating competition from other fungus and mold. It IS possible to use unpasteurized straw or manure & hydrate on site, but I do not recommend it.
#4 Bag the substrate for transporting to a remote location.
Make sure the bag you use can sustain the weight of the substrate and the water. Regular trash bags usually don't hold up too well.
#5 Crumble a bottom layer of straw or horse poo in a very shady area (a circle, square, or a line-like row will work), keep the depth fill in mind when choosing shape.
Try to avoid pine trees because their needles make the ground soil acidic. regardless, if you do use pine areas, cover all the ground so it is a solid patty. Make sure this layer has sufficient air and will drain if it rains hard. No flat solid mats, that would invite anaerobic molds... a light aerated mat. #6 Shake & apply your spawn on top of the layer you just placed down, 1:4 ratio is what I use.
If you are using cakes, obviously these need to be crumbles to make multiple spawning points. Grain spawn naturally does this so the jars just need to be shaken hard.
#7 Lightly sprinkle more straw or horse poo on top of the spawn to cover it like a casing layer to protect the spawn from contams & drying out.
Again, make sure these layers are aerated and fluffy to avoid unwanted anaerobic molds from growing. you can pack the whole pile together tightly when the layers are completedbut only after. This takes a bit longer to perform but its worth it to know the pile even and will breathe well. A layer of pure coconut can be sprinkled over the over top layer like a casing layer or mulch.
#8 keep the patch well hydrated and wait for the harvest.
It's that easy, no digging holes or soaking straw, simply wetting the manure will hydrate it enough. If you even wanted to you could also bump up the Nitrogen level by adding 1 Tsp. of blood meal per 8 cups of horse manure. A lazy person could simply sprinkle the blood meal on the top of the patch and let it wash into the patch overtime; but i prefer to mix it in during the hydration process. The problem with a lazy method is the unknown measurements, so if you are lazy aim lower rather than the high end, or else your efforts will be all for nothing, and you mycelium will be chemically burned.