Wood chips mixed with the soil will tend to consume N until they have decomposed. Whether that is a problem for your trees depends upon the N content of the soil prior to the chips, and to some extent your climate. But unless the soil had a bunch of N (a lot of manure or the like) then most likely it will be N deficient. A problem is that you can't really test right now as it is still winter (depending upon your zone/location), and so the chip decomposition bacteria and fungi are not yet in full swing.

You could plant and monitor the soil's N values during the growing season, and adjust with supplemental N as needed, tapering off towards fall to allow the trees to harden off. Although the timing of this may be tricky.

Wood chips in the soil with require high amounts of nitrogen to break down. Not a good idea. The bacteria will pull the nitrogen out of the soil to break the wood down, and that nitrogen will not be available to the tree until they are done. Mushrooms will grow on the wood chips buried too, you should form a nice crop of shrooms! You would never want to put raw manure near a plant. Composted is fine. Let it sit a year before using raw. But not ideal. Usually compost is not used around trees. But if you have wood chips in the soil, heck it might all balance out! I would use 100% native soil. It has to eventually grow in it, and current thought is to just start them in it. But I understand you want to make mounds which is an excellent idea. That follows conventional advice these days. Mound your trees!

Thanks for the replies. Mabey I will make the inner circles of the mounds mostly native soil and add the horse manure to the chippy stuff around the outside.

As far as the raw manure goes, wouldnt' it be ok if it is getting "rained in" slowly over winter with a layer of mulch separating it from the roots? That is if we get some rain. Real bad drought in northern CA.

"As far as the raw manure goes, wouldnt' it be ok if it is getting "rained in" slowly over winter with a layer of mulch separating it from the roots? That is if we get some rain. Real bad drought in northern CA."

Yes, it is composting that way. It's better. I don't know much about it, but I heard it can be hot, and have too much nitrogen and burn roots. So this sounds like a way to compost it under the trees. Seems OK, but I'm no expert.
Part of the problem with say bringing in better soil is the plant tends to not want to leave the better soil, but on a mound that is a little different. In flat ground you can cause a bathtub effect. Where the water pools in the new soil. This isn't a problem here. When amending is needed, they say to mix with native soil, so that would help too.
By next summer you can mix the manure deeper in.
Once the trees are a little older, you really don't need to fertilize. The horse manure aged a year is great for gardens. I wish I had a source.

There is concern in some parts of the country about mixing wood chips with soil contributing to disease issues and for this reason alone it may be wise to use it only for mulch, which is considered safe in this regard.

However, for decades I've read of using wood chips as a base to help create raised beds- particularly in vegetable gardens. It can also be used this way for trees, but I would at least contact my cooperative extension to assess the local disease pressure that might be involved in this approach. Such raised beds will settle more quickly than something more stable as wood chips break down- rapidly losing volume.

Bacterial activity on the woodchips is drastically increased when it it incorporated into the soil compared to its use as a mulch and the carbohydrate to nitrogen ratio in wood does lead to the bacteria pulling N from the soil to complete their dietary needs. This happens even when used as a mulch, but the slower break down and the fact that N is only drawn from the soils surface will usually render this mute as an affect on the trees.

Over time the affect of the mulch actually increases the overall N. content of the soil as the N feeding bacteria die off and the N from their bodies combined with the contributions of organisms that pull N. out of the atmosphere push the equation the other way.

N. derived from compost and organic matter in soil tends be delivered to trees at greatest rates when soils are warmest which encourages vegetative growth- good for establishing trees but not necessarily helpful to bearing age trees.

This means that if you are growing fruit organically you actually can benefit by the judicious use of raw manure spread on the surface in early spring or early fall, particularly urine soaked bedding, for a quick shot of water soluble N that will be drawn for use of the spur leaves when energy is going to fruit formation in early to mid spring.

Another problem with wood chips for raising beds is that as they decompose, they shrink and the beds sink, so they're no longer raised. The tree will sink with it so you can't keep adding soil, as it will cover the graft union.

Blueberries do well in soil that has been amended with various kinds of vegetable fiber, including wood chips. I think this has to do with providing food for fungi that ultimately colonize the blueberry root system, and over time enhance to ability of the blueberry shrub to take up nutrient from the soil. I can't say for certain that cherry trees would benefit from wood chips. I agree that the soil will settle as the chips decompose. With regard to nitrogen sources, I would be inclined to use something like Miracle-Gro or Schultz's Plant Food, diluted with water and applied per the label, in order to be certain that the tree has sufficient food to grow well. If I had manure available, I would compost this material before using it on my orchard.

Thank you all! So, I guess even horse manure is too hot for fruit tress. I have a whole truck of it now. I will try and find a good place for most of it and put a tarp over it for next year and just put a little on top of the mulch of my trees to get rained in over winter/spring.
Guess I'll make the mound bigger to make up for the settling. Thanks for that heads up harvestman and i'l check with the Ag ext. on the specifics of Cottonwood chips in my area.

Thank you all! So, I guess even horse manure is too hot for fruit tress. I have a whole truck of it now. I will try and find a good place for most of it and put a tarp over it for next year and just put a little on top of the mulch of my trees to get rained in over winter/spring.
Guess I'll make the mound bigger to make up for the settling. Thanks for that heads up harvestman and i'l check with the Ag ext. on the specifics of Cottonwood chips in my area.

If the horse manure has dried, it won't contain that much nitrogen. Most of the nitrogen escapes as ammonia as it dries. What you apply will mostly be organic matter, minerals, and other nutrients with a smaller amount of nitrogen.

Cool, thanks beeone. That's the confirmation i've been waiting for. I think the trees will appreciate a top dressing of it to rain in over winter. i just have to pray for the rain.

Horse manure can also contain weed seeds.It depends on the source.A friend told me once,he used it on a garden and they were coming up all over the plot.From what I've read so far,it's difficult to get it hot enough during composting to kill them. Brady

thanks Brady. I'm guessing if horse manure is not hot enough to kill weeds it's not going to be too much N to put a thin layer on top of the mulch around the trees. i have started doing so about 6 inche away from trunk to about 2 ft out from there.
Hopefully the mulch will be enough of a barrier to prevent the weeds sprouting. I'll plan on a round of weeding in spring anyway.

I never worry about weed seeds around fruit trees because, at least with establishing trees, I maintain a thick, wood chip mulch over any manure I might use.

These days I don't actually use much manure but I used to collect free stable waste from horse farms that was a mixture of shredded wood, urine and manure and I'd use it fresh when mellowed wasn't available. I've never hurt a tree with it, but I usually spread it in mid to late fall.

I just have to tell the story my dad tells of gardening when he was a boy-using humanure. Apparently humans don't digest tomato seeds well, and boy they had lots of tomtoes in their garden.