I doubt N deficiency is your issue if you've been mulching like that all this time. Subsoil isn't where the roots are going to extract minerals if the topsoil has a decent balance of air and water and by now your topsoil must be more than rich enough to support vigorous tree growth.

A soil would have to be extremely acidic to restrict fruit tree growth and even a very thin layer of more neutral soil should be adequate to restore vigor. Your mulch should have long since achieved this result.

I have found that stunted fruit trees are usually the result of a factor other then nutrition. The most common cause is nearby forest trees or any very large trees that have root systems already well established in the soil one is trying to establish the fruit trees. Even supplementary water and fertilizer cannot fully compensate for this kind of competition which can even include a kind of chemical warfare know as aleopathy (a war that more than walnut species are armed for).

If you dig a hole in the area where your fruit trees are and there are a lot of other roots- enough to restrict your shovel, this is probably the problem. Otherwise you probably have some other soil issue that doesn't relate to pH or N deficiency.

It surprises me that competition from other established trees is generally overlooked in the common literature about establishing new plants while competition from weeds is frequently sited. So much of what we know about growing plants is established in agricultural conditions where this kind of nearby competition is not a factor. Herbaceous weeds, however, are an issue in any cultivated field.

If fertilizer is an issue the odds are N is the mineral most likely to achieve a response and the source is not very important, at least in the short term, as long as it is quick release and applied either in the early spring or very late summer to early fall.

Foliat feeding might be worth an experiment too early next spring. Maybe a few separate sprays with a complete soluble fertilizer. The urea in it should solve any N issue, at least temporarily.

You've had the soil teested?

Year 5 after planting is as early as I hope to get fruit. A few trees are sooner, a few trees are later.

Try a light feeding of 10-10-10 in the spring, or 15-15-15.

9-3-6 or 18-6-12 is probably the best way to go, but I've never found one that wasn't outrageously expensive. I can get 15-15-15 for very cheap and then the plants just don't use whatever is excess.

My last bag of 9-3-6 was nearly $50 for a 40 pound bags. My last purchase of 15-15-15 was $12 for a 50 pound bag and the trees are perfectly happy with it. I use the expensive stuff for potted plants.

I do not feed my fruit trees very much or very often. If you feed them a lot, they will get a lot of vegatative growth but perhaps not uch increase in fruit. Fruit flavor tends to be better if trees aren't over-fed.

If the soil tests too acid, you might have to top dress with some agricultural sulfur.

Smoke, you mean lime.

Someone explain to me why these trees would need supplementary N. with the amount of mulch that's been put down which includes grass clippings and manure, which are both high N, especially the grass clippings. The mulch would also compost out close to neutral so the extra N is bound to be a waste of time and acid soil is probably not the issue.

I agree with Smoke that the question about soil testing is relevant but I establish fruit trees for a living and you probably should look at my suggestions as I look at 100 different soils a year. When the trees I plant don't grow well I have to solve the problem or I lose money.

I would look at the possibility of a micro nutrient deficiency as well (or even an excess) although that's never been a critical issue for me on any site that originally didn't produce vigorous growth. Most of my experience, at least in the last 30 years, has been in the northeast, however.

There is a book published within the last couple of years putting together research about roots compiled over the last 100 years. It is worth reading for any serious grower. It is "Roots Demystified" by Robert Kourik. My little family orchard is carved out of the woods and roots from the woods extend at least 100 feet into the orchard. When you look up how much water and nutrients a 200 foot fir tree can pump out of the ground per day, no wonder my fruit trees are struggling. Al

Somehow I forgot I posted this, will add some more info...
Thanks for the tips already here.

The trees were moved once after 2 years because their initial location was too wet. They were then planted in mounds. I root pruned in spring and transplanted in fall for easy transfer.

The actual subsoil is wet and actually very high in actual peat mixed with thin layers of clay/silt- so it is highly acidic. Was an old bog here, historically. No I haven't tested the soil and will this spring, not sure why I haven't- likely because I figured I knew the answer.

The only tree to actually fruit is a horrible scarlet sentinal apple that had actually been moved 4-5 time in 7 years, been chewed by voles nearly every year, and was planted in what turned out to be a puddle for 2 years. Instead of yanking the ugly thing I've decided to move it this spring to a "forever" spot up against the house and take care of it. Yes... it will likely die at that point, I know how it goes.

And there are no nearby trees (150' to the nearest). There is grass around the "mounds" but it has not really encroached the tree mounds yet.

So they aren't actually growing in soil that has had the benefit of heavy mulching for 5 years and their roots were pruned in spring before being transplanted (the rootsystems were too extensive to try to dig them all out?). Have they only been growing in their current site for 2 seasons?

For a weak growing tree it might take 2 seasons to recover from a transplant where you've removed most of their roots- the fine roots at the end of the cuts would have been killed by transplantation.

They've been in their new location 3 complete years.And with that I moved them in huge plugs of dirt (root pruning alled for very little root loss).

GW would not allow two posts in a row yesterday- and what got missed was that the woodchip mulch would likely have removed usefulness of the grass clippings N, and the manure was added Hot in fall just in time for the goodness to get washed out.

Last fall I covered the manure with wood chips in hopes of encapsulating its usefulness.

I realy do think the subsoil is lacking something and I willl have to test it in spring.

The first years application you may loose some N at soils surface with wood chips but in subsequent years it should at worst be a draw, gradually supplying substantial N as it turns to humus. Bacteria actually begin to pull N from the atmosphere in the medium created by pure wood chips. I learned this part on this site but I've known for years that woodchips rarely cause N deficiency for woody plants. Annuals have their roots initially right on the surface so they can be set back.

Fruit trees can pull up N in the early fall as long as they still have some leaves and this is actually a pretty efficient time for application as they tend to send out a surge of fine roots at this time.

Grass clippings supply a very steady release of N and to a lesser degree so do leaves which have a ratio of N to carbohydrate that shouldn't ever create N deficiency.

Anything composting around your plants can pull N from the soil until properly broken down. I mulch around my fruit trees with grass clippings maybe 3 or 4 times a year but my main reason is for a more natural way of weed reduction around the base instead of using sprays all the time. Another added benefit mulch has is it also attracts worms. The down side is, worms attract birds, so I avoid when fruit is ripening. Also when I do much I also add sheep pellets to help against the initial N reduction. & one thing I didn't see here, so I must mention is grass clippings can make the soil more acidic which is great for the Blueberries but not so much for my other trees, so to battle against that I just add a little dusting of lime also. Lime helps to neutralize acidic soil.

Best advice though is educate yourself on the needs of each type of tree, & buy a soil testing kit. Once you know the soil is right for the trees you can then look at other reasons that may be causing problems. Every place around the world is going to be different so I enjoy experimenting with my trees to see what gets me the best results every year. Of course taking into account that you always have an, "on season" then an "off season".

Be aware that giving too much nitrogen to young fruit trees will cause the plant to focus on growth and leaf foliage at the expense of fruit production. If you are impatient and want to start seeing some fruit as soon as possible, adding concentrated nitrogen fertilizer is probably not a good idea.

Actually this is the main reason fruit trees are grafted, in many cases, to stunt the growth so it will not take 10 years to start producing fruit. Dwarf varieties can begin producing fruit as early as 2-3 years.

That's ok parker, it's kind of what I want with the new trees I stuck in last summer. I'm happy to wait for 3-5 seasons to get my 1st lot of good fruit from new trees. Most important to get a good branch & root structure going 1st. & just to add a little more on your comment, over ferting of any kink is bad because if the roots have all they need right there they wont bother going in search of what they need. Small roots, small tree. Now we're talking bonsai. Also you're wasting money putting down fert that the tree isn't going to use. & in our case living in the country that wasted fert is then going to leach into the waterways. Not what I want.