I can't answer about how much - it all depends on what your soil looks like, what you going to plant and when and so on.. However, I can point you to the difference in what "horse manure" could be. The manure you can get from big horse farms usually contains 70-80% of bedding, that is mostly wood shavings. They do not break in a year... They sometimes do not break even in 3 years, if you didn't mix it very well with the soil and have a clump left it here. They take away your soil nitrogen. I only used this type of manure for mulching, after composting it for a year. But even this, mixed next year with soil made the soil worse, not better. Then I found a source of strait horse manure - the lady doesn't use bedding, it is usually mixed with a very small amount of hey. This is a real, good staff. But even this one I only add after at least 3-4 month of composting and only to the cultures that love nitrogen - mainly cabbage. The rest goes in compost pile and makes nice black compost. At first it heats up for a while, and then worms start to work on it. It attract so many worms, that it looks pink when you touch it with a shovel. So it is almost vermicompos when it is done. This is how I know it is done - worms go away). You also can add leaves and green staff to it, but normally N/C ratio is good as it is for composting in the horse manure.
Sorry if I didn't answer your questions, just shared my own experience.
Good luck!

a little over 21 cubic feet, so close to one cubic yard. If you do not bury it, the shavings will not rob nitrogen short term, however, when you do not bury it about half the nitrogen evaporates, so long term it is worse.

Thanks for the replies,
So If I'm understanding this correctly, I should know if the horses have been eating wood shavings. If so, the manure has the potential to suck up the nitrogen in the soil. And also, I should plan on digging it is so that about 50% of the nitrogen does not evaporate which would only make the wood shaving problem worse. Do I have it?

Two rows at 32 feet by 4 feet gives 256 square feet. That is 21 cubic feet at one inch depth or 64 cubic feet at 3 inches deep. The three inch depth gets you 2.3 yards, or one full sized pickup truck bed loaded to the gunnels. Three inches of horse patootie dug in six months down the way isn't going to hurt your chemical balance at all.

There's no need for gloom and doom in adding organics to the soil. Load it on and either dig it in right away or wait to dig it in next Spring when the ground's dried out. Nothing will be wasted under snow.

One false idea that many people have is that manure is good fertilizer. It is a terrible unbalanced erratic unreliable fertilizer on it's way to becoming compost. With (say) three truckloads (the horse guys hopefully have a bobcat rather than handing you a spading fork!) of material, and if you have the room, put EVERYTHING into a compost pile and only use the results of that. The wetter the better. You can start now, spread some on the rows now, and still have an amount of compost for the Spring.

The more long-term you can make gardening, the easier it becomes. Piles are slow but piles are long-term-reliable. You can even leach compost/manure tea from them. And with piles those brown-green carbon-nitrogen ratios are moot.

Dear grubby_me,
That is encouraging and sounds reasonable. I have a feeling I am shoveling the stuff myself - but I don't know yet. I will get a truckload for this year and see what happens.
Thanks.

Horses don't eat wood chips- that is bedding the horse stands on. It get put into the manure pile along with the poop when cleaning. So it's likely a lot of bedding mixed with some poop.

I compost straight manure from my girls. If I put it directly into or onto the raised beds, it will be pretty much still there in spring. I have no idea why it doesn't disappear like it does in the compost pile but it doesn't.

Horse manure is interesting. Bedding could be good (straw or wood shavings) if it is urine soaked. But a lot of times the way they clean stalls is they just go through it with a fork. The wood shavings, wet or dry slip through. Only the manure is caught by the tines of the fork.

The wood shavings would only come into it when they "muck out" the stall altogether, removing all the old bedding material down to bare ground. Like I said, if it has urine in it, even this might be good stuff, but it would probably be best to let it compost.

Getting to the crux of your question, I think adding an inch of manure now, and tilling it in, will very likely be a good thing come spring. I would avoid tilling in large amounts of wood shavings. But it will be visually obvious if the manure has lots of wood shavings.

Last year I put a fair amount of horse manure in one of my beds and mixed it in. And it seemed to work well for radishes this spring. Mind you, where I live we don't get snow in the winter. Just a light frost in the early morning hours.

--McKenzie

I used horse manure (partially composted) two years ago and regretted it.

First: the wood shavings issue: true. Most places use some king of stuff on the ground to soak up the stuff, Wood shavings, straw, rice shells, other husks etc. That all goes into the manure.

I picked up the manure from a farm. He told me the stuff on the back side of the pile was at least 6 month old (partially composted).

Biggest problem: I had unending growth of weeds. That is when i learned that horses don't digest the seeds and they stay in manure even for 3 years. So you will be pulling a lot of weeds.

As I built each raised bed (needed due to gopher infestation), I forked/dug down as deep as possible, then added clean horse manure, partially composted. I watered and turned this as much as possible, then I built my boxes with hardware cloth for the gophers. Finally, we got some organic planting mix to fill each bed (we did about 1-2 beds per year). Less weeds and a lot of HM goodness!
I know nothing of snowy areas! LOL Nancy

Yes, I have seen a lot of weeds in horse manure, too. But I have a lot of windblown weeds anyway. So When I put it in in the early fall, I watered and covered the bed with black plastic. This caused almost all of the weed seeds to sprout immediately, and then they died due to the lack of light. I think it took about 2 weeks.

--McKenzie

It doesn't change what you get, but from decades of experience with horse poop, I can tell you that most weed seeds do not go unscathed through horses except for grass seeds. But a lot of the weed seeds in hay get dropped into areas where the horse eats and into the bedding. And a lot of seeds happily grow around a poop pile left in a field to get picked up there too.
I found if I pick up the manure daily, I get almost no weed growth.
But the unlikelihood of a non-horse person to be that selective about the manure they get means it doesn't matter in the end- you get weeds unless you get the compost pile hot enough.

I get some partially rotted horse manure that has quite a bit of hay in it...no wood shavings. Yes, I get some clover seedlings sometimes....not weeds. I work it into many areas in the late summer or fall. I do avoid lettuce and spinach areas and also lima beans, sweetpotatoes, and melons. The reason for avoiding melons and sweetpotatoes is to cut down on fungal diseases. For limas...it makes them grow too big and bushy and delays bean bearing.