aged manure

Asked May 14, 2020, 9:55 AM EDT

I recently purchased a farm with a large cattle barn and piles of aged manure. Can manure age out? Not sure how long it's been there, I have owned the property for 2 years. It's pretty dry and in more of a peat moss looking state. If usable, what's the best way to incorporate, should it be moistened or chucked into the compost, can it be directly added to amend soil?

Ionia County Michigan

1 Response

Hello and thank you for using eXtension for you composting question. you have a couple of good questions here. And I will respond to comments not in a question that should be. I will address them in the bullet points below

· Q. I recently purchased a farm with a large cattle barn and piles of aged manure. [Is it composted?]

o A. piles of manure are just that, piles. If the piles have dried out because they are inside the barn or are in very large piles outdoors, then the composting activity has stopped and they are not yet compost on the inside. My recommendation is to turn and re-pile it, wet it down and see what happens. If it smells or heats up you need to finish the composting process.

· Q. Can manure [compost] age out?

o A. Yes, if compost piles are outdoors. Just like soil, rain water leaches the nutrients out of the compost and reduces to its base mineral elements over time. Figure unused compost leaches out in about 3-5 years depending upon the pile size and mineralization has started. Recommendations are that compost be applied within three years of finish. However, if you see a lot of uncomposed materials in your piles, hay or grasses, then there are organic materials present and nutrients that can be re-composted. Turn and re-start the process.

· Q. If usable, [is it usable?]

o A. Your compost should still be usable regardless of its age if it was properly composted. If it wasn’t and it is still composting, once incorporated it will re-start the process but caution should be used because the uncomposted bits can cause pockets of nitrogen take up and or burn tender seedlings. Even mineralized compost is useful to add to gardens, it just will lack nutrients requiring the addition of fertilizers.

· Q. What is the best way to incorporate, should it be moistened or chucked into the compost, can it be directly added to amend soil?

o A. I would guide you back to the first answer before adding to your gardens. When adding composted cow manure to your garden use it at an 8:1 ratio of soil or mixed with other compost to manure. To put it in other terms less than one inch deep applied on the surface or mixed with something else, unless you are certain that it has mineralized. Then you can incorporate into the soil a bit more heavily as any chance of burning is pretty much gone. Manures are very high in phosphates so regular soil testing to monitor or testing your compost is important. Both can be done through MSU Soil Labs https://homesoiltest.msu.edu/. I don’t recommend using it on vegetable gardens for human consumption as manures can still contain pathogens.

To recap briefly, yes you can use it, check to make sure it is finished composting in the middle of the piles, and use wisely.