I’m pretty new to composting, and have been following the composting work of scientists like Elaine Ingham and David Johnson. I’m looking for advice on composting materials I collected. I am attempting to build a large 4’ diameter composting bin. I collected manure from a friend of a friend’s residential farm (donkeys, goats sheep and chickens) and I ended up taking the more mature manure which was mixed with straw and turned periodically and looked like it was already mostly composted. About 10% of it was pieces of manure. See photos. My plan is to go back and get fresh manure for my compost pile to get a proper C/N ratio, and possibly use the mature manure in the garden. Is this risky? Should I put the mature manure back through a full composting cycle? Or maybe put it through a pasteurizing heat process before using it in the garden?
First off, don't kill the lovely mycelium you have growing in that aged manure.
If you want to kick start a new compost heap, that stuff is golden, just add in mixed with some fresh and you will get a really good finished compost.
If you want to use that aged manure now, go for it, it is ready as is or as I said above, you can use some of it as a biological seed in a new compost heap.
High quality hay sounds nice but was it sprayed with anything? do the animals receive antibiotics? do they get a wormer? These are the things that can make what should be good stuff not so great.
You just need to know so you can approach using it in a method that if needed, will remediate and cleanse those not so great material residues out of the way so they don't affect your plants or soil microbiome.
I ended up needing to use all the fresh manure and mature manure in the compost pile, and I still only made it to about 3-1/2 feet high. I will try to get more info about the hay and any animal treatments. This type of compost pile is meant to go for 6 months to a year, so I'm curious if that is enough time to break down any of these harmful substances.
I originally left out the details about the composter. If anyone is interested, here is a paper on the composter: Johnson-Su composting bioreactor and a youtube video of Dr. Johnson building one: youtube video
Six months is going to be far and away enough time for the mycelium to do their work of remediation on any of the possible chemical compounds, so as long as the heap behaves as a heap should, no worries.