I've been making compost for 20+ years and will offer a few thoughts on "composted" manure.
Old manure is not necessarily "composted" manure.
They typically classify the ingrediants in compost into 2 categories, Green stuff and Brown stuff. Green stuff contains nitrogen, the Brown stuff contains more carbon. Combine the two, with Moisture and Air, and that's when you get heat, which indicates thermophilic reaction, or "Compositng".
Not to bore anyone with the chemistry.
Green stuff: Manure, grass clippings, vegetable and fruit scraps, etc.
Brown stuff: straw, wood shavings/sawdust, fall leaves.
Brown stuff has a lot of air in it, so keep this in mind.
I use lime and/or woodstove ashes to balance the Ph, as well.
I have heard a lot of different formulas over the years, but, to be general about it, and following what i found that works well, is you need more Browns than Greens. 3:1 Browns to Greens works well in my book.
By weight you can use a 1:1 ratio.
By volume it may be 20:1 or 30:1, Browns to greens, this is due to the fluffier brown material which contains a lot of air.
What does this mean for horse manure? To me, it means unless you use a ton of bedding material, and change it very frequently, you probably won't have enough Browns to fully compost the manure. It's most likely that the typical horse stall clean out will probably need more Browns. (By weight, not volume). Fresh urine is
very high nitorgen, so, add that into the equation, again, more browns are needed for full decomposition.
The heat of the pile will tell the tale. I would say that if your pile rises above 130F degrees in the first 24 hours, then you have a good initial mix. My piles have gone as high as 180F in the center. To kill weed seeds, technically, it has to go above about 125F (that's what I have read). The weed seeds "cook" and that's what kills them. When the temp of the pile falls below 100F, it's time to stir the pile. This time the temp will rise, maybe not quite as far, but it should rise. You mgiht end up stirring 3 or 4 times for full composting to take place. Once it doesn't rise above 100F , you probably have 90% composted material. the last 10% of the action could take months, if you want to take it all the way. This would be more for fine gardeneing, potting plants, etc.
If you spread your "composted" manure and get a lot of weeds and volunteer action, then it wasn't composted fully, just old.
Too dry. This might be simply not enough water, or, it may be the Brown/Green ratio is not good enough, and the reaction is sucking all of the moisture out, before it has a chance to react well.
I do use manure in my compost, but I find I get better compost when using a wider variety of materials. Manure, straw, grass clippings, leaves, woodchips, kitchen scraps. it seems the more diverse my materials, the better all of them break-down to true compost. For me, the more variety of stuff, the merrier.
My buddy has 4 or 5 horses and one of those huge piles of manure that he cannot get rid of quickly enough. Some of it is upward of 2 or 3 years old.
I can tell you, it's old, but it's not composted. When I mix it with my other stuff, it starts breaking down quite rapidly.
I am sorry if this sounded like a lecture. I just wanted to give the basics for actual composting, and explain what I have learned about how manure fits into the equation.
Needless to say, I find that people often confuse old manure with composted manure. If it resembles potting soil or loam and has worms in it, you have some good stuff.
-Another thing I find about composting manure, the better composted it is, the less flies you have! Fully composted manure doesn't attract flies. If your summer pile has flies buzzing, it has more raw material than composted material.
Once you get good at it, and mix the proper materials, you can fully compost fresh manure in about 30 days, and spread it with no fear of massive weeds or worry about keeping the grazing animals off of it.
Again, sorry for the "lecture" tone of this. I'm hoping it helps anyone reading the background of getting the material to decompose faster and better.
I'll be glad to answer any questions after the Pop Quiz.
The SkunkWerx Compost formula:
-Proper ratio of greens and browns. Wider variety of stuff is better.
-Minimum pile size 1 to 2 yards (smaller piles have trouble heating up and staying hot).
-Shredded stuff decomposes faster (mow or shred leaves first).
-Water the pile as it's stacked.
-Throw in some regular old dirt to add substance.
-Better than dirt, Mix in some old compost, soil, or loam from the forest floor (adds the enzymes and bacteria to help form the microbes that does the work).
-Mix in some lime or ashes to counteract any acidic nature of the base materials.
-Check that the pile heats up well.
-Remix when temps fall off. Repeat until pile no longer heats up. remiing is vital to add air, it's also a good time to add more moisture, if needed.
-Even once pile no longer makes heat, the cooler temp bacteria take over and continue the final process, along with worms. This last part is sometimes called "finishing the compost".
For finer gardening screen the compost at approx. 1/2" size. I find screening smaller than 1/2" makes the compost compact too easily. 1/2" gets out the crud, but gives plenty enough air and tilthe for plant growth. 1/4' is the absolute smallest i would ever consider for screening.
