Hugelkultur over huge norway spruce stump?

Hello all, I'm new to permaculture, but have been reading Gaia's Garden and this site lately.  I live in Western PA, which has had some really wet years of late, and just had a very large norway spruce with needle blight [which should not be transmittable] cut - and left, chips, trunk, and all - on the property.  Our soil is very poor, mostly clay and rocks, and I was planning to build a raised bed for $$ when it occurred to me i might re-arrange the trunk sections - 15' each - around the stump, which is probably 3' diameter but cut to pretty near the soil surface.  Then I'd pack in the smaller limbs and as much grass and greens and decent soil as I can get, and end up with a large raised bed.  

My questions are -- would this be too large?  I'm 5'3" and the trunk sections come to my knees - I won't be able to reach anything like the centre of the bed, if it covers the stump and roots, and is edged by the trunks, even if they're cut down from 15'.  Also, we're in heavy deer country, so if I plant anything edible it'd need a fence on top of the trunk sections, which unfortunately I won't be able to dig down into the soil probably at all.  So I'd likely need a gate of some sort, and may end up compacting a path through the middle of the bed lengthwise.  I'd probably plant a couple rounds of nitrogen-fixers on top, cut and let lie, before anything of value.  Is this volume of spruce just going to be too much, do you think?  Suggestions?

The site should get 9 hours of summer sun, has no sod on it now, and probably I'll continue to age the wood chips and use them as acidic mulch in a year or two, instead of adding them to the bed.  I could post a photo tomorrow if it'd be helpful.  Thanks for your time!  

Welcome!

You raise some good concerns regarding access and compaction.

Another deep mulch design option to consider is hugelkultur. There are many threads that go into great detail here, so I won't try to recreate that content. But to summarize, you could layer the log, debris, leaf litter, and chips into a mound that over time would slowly break down into rich soil.

On the down slope of the mound, you could plant fruit / nut trees and the captured moisture and rich soil will benefit them greatly creating a "food forest".  There are threads on food forest planning and succession here too.

I'd be leery about burying spruce (or any evergreen) in a hugelkultur style application. Most evergreens are at least mildly allelopathic: they could affect the growth of whatever you plant above them. It's not a 100% "ever do this" scenario, but it would be worth your time to research the subject a little deeper before plunging ahead.

Hello, thanks very much for your replies!  I considered further today, and may have a better plan -

The 4' stump is nearly level with the soil, but has roots galore, so I won't be digging anything in any time soon.  I know spruce isn't the choice wood for hugelculture, but I've got a lot of it!  Two three-foot diameter 15' long trunk sections, and four smaller diameter ones -- what if I created three beds and two walkways, with the larger trunks on the outside aligned N-S (this area of the property is flat, and as full sun as I get anywhere in the yard)... I could fill in with winter branches and some big shards of sugar maple that just lost a huge trunk, but I'll have to bring in soil, too.  This way it won't be loads of evergreen wood actually *in* the hugel beds, but decomposing more slowly as the edging, and the trunk a couple of feet down.  I do have a lot of really slow-decomposing ornamental grass reeds (it's zebra grass) - is this okay near the bottom of the beds, or will it form a water-impervious layer? I don't have a chipper or mower with which to mince them...

We're absolutely crippled with deer here, so I'll probably fence the beds, and use them as our only "edibles" area - the veg, herb, and tasty flower patch.  I'd add a walkway at the front with the door - since I can't reach across 4 feet, the outside beds would be narrower, but this would eliminate the giant-bed compaction and access problem.  Since I can't dig down, these beds would be probably 2.5 to 3 feet high/ deep, like the trunks.  I could plant a couple rounds of cover crops - alfalfa and/or Austrian winter peas in the beds to add nitrogen and chop-and-drop greens, and will be filling up the unfenced areas of yard with lupine and anything else that won't be devoured, like bee balm, new england aster, goldenrod, and foxglove.  

I'll probably try to turn the 5' mound of wood chips, let them season/ compost another year, and them use them as mulch or lasagna layers around rhododendrons and mountain laurel, etc.  Or I could definitely put them into the beds, if it wouldn't be too much nitrogen depletion, and too much spruce?  

Critiques and further advice welcome!  Thanks!

Hi, I think it’s great idea K Cook. I don’t know Norway Spruce in particular beyond the Wikipedia reference, and the European species that American trees are named for are often almost completely unrelated. They simply have some quality reminiscent to their Euro-American taxonomists of their namesake. Still, I have had excellent hugelkulture results using primarily conifers of several species that are not particularly well preserved. The main species I avoid are the extremely rot resistant cedar and redwood here in conifer country in NW U.S. Sitka Spruce, firs and pines are all excellent in hugels for many common plants. Those I have tested with great success are strawberries, grapes, curcurbits, sunflowers, wildflowers of many kinds,many kinds of leafy greens, garlic, onions, beans, radishes, basil, potatoes, and probably several I am forgetting. The nitrogen robbing theory about wood in soil is less true the larger the wood particle size gets, with it being negligible above forearm size, due to surface area ratio being the key factor. Large woody debris is the real tipping point factor in making a temperate old growth forest what it is, a temperate place in temperature and humidity due to the thermal mass and shade of the trees above their fallen branches and ancestors. 75% of the moisture in August in a Pacific NW old growth coniferous rainforest is in the dead wood. This hosts the greatest soil biodiversity on Earth, which is fungally dominated. This soil ecosystem is obviously advantageous to native, coevolved species like the conifers it supports, but it also seems to benefit many of our common fruits and veggies in my observation, and does so in the first year. Here is a before and after with some produce of a new (planted within a week of finishing). Others have had even better results built taller.

Thanks, all!  I think we'll do it, as no one has called me crazy today, trying to talk them into helping... I'll take some before photos, and some after, and post both after whenever "after" ends up being... I'm excited to try it!  
Your photos look great, Ben, thanks for posting.  I think Norway Spruce are only moderately rot-resistant trees here in western PA, and my pieces are well over thigh-size, so here's hoping it works out well.  I'm actually in the middle of one of the last / best stands of old-growth (hemlock and white pine, mostly) in the Eastern US -- Cook Forest State Park  The forests floors are wonderfully spongy and wet, as there's no salvage/ removal of fallen trees, limbs, or leaves/ needles in the park.