Cold Climate nitrogen fixing trees

Hi Permies! long time reader first time commenter.

looking for a nitrogen fixing tree for my area (east coast of canada, bay of fundy, zone 5a) I have about 30 fruit trees planted so far in 3 different areas on my farm, Apples, Pears, Plums, Cherries, Peach and Apricot. I am planting in guilds designed to come together over time, but I still haven't nailed down the large N fixing chop and drop element.

I have grown out honey locust collected from trees my area but the spikes are pretty gnarly. I am a barefoot farmer so that has been ruled out for me, gonna dig up the ones I already have planted in zone 2 and move then to a zone 4 area and hope that they don't grow back form any roots I miss. I have a few sea buckthorns bought from the nursery, but they haven't really done very well so far on my land. I started a bunch from seed this spring so hopefully they will be more productive that way. I have a couple of siberian peashrub which look promising, but its too early to tell.

I guess I am really wondering if anyone in my climate has had success using speckled alder as the n fixer? it grows in the wetter spots of my site and is the first to take over old fields in this area. I know my dad and grandfathers would think I was absolutely nuts for actually planting speckled alder, but maybe that is the sign that its the right thing to do from a long term soil building standpoint? following natures signs instead of fighting them?

Alder should work well. Russian Olive and Siberian Peashrub?

I have Autumn Olive, Seaberry, Siberian Pea Shrub, honey and black locust.  Honey locust is easy to find in a non-thorny variety, and is used extensively as an ornamental shade tree here.  I find them really beautiful.  I have a couple hundred planted right now that I started from seed.
Some of them grown from seed will not match the parents and will have thorns, but I have plenty so I'll just remove those if it becomes an issue.  My Autumn Olive are improved varieties that don't have thorns.  Siberian Pea Shrub doesn't have thorns.  You mentioned Seaberry, but my Seaberry bushes have thorns as bad as honey locust.  I have never tried Alder.

Autumn Olive makes a great guild tree for me and I have them around my apple trees and spread around my land at different places.

Be careful with the Russian Olive, some places here in the states consider them invasive species and you can get in trouble planting them intentionally.  Not sure about your local area though.

Jonathan Ward wrote:Be careful with the Russian Olive, some places here in the states consider them invasive species and you can get in trouble planting them intentionally.  Not sure about your local area though.

Autumn Olive is considered invasive here as well, but what am I to do if they just happen to pop up around my apple trees?

I'm not sold on autumn olive either, although it is reccommended by alot of the folks I follow on the net.

any suggestions on how to propagate alder? wait for seeds in the fall? or will spring softwood cuttings be worth trying? they grow so easily on their own that it will be funny if they are hard to propagate

Black locust thorns are nothing like honey locust thorns, so maybe you'd like that one.

I was curious about the speckled alder and looked it up.

According to the maps on wkikipedia
https://en.wikipedia.org/wiki/Alnus_incana
Eastern Canada is the native habitat of the rugosa subspecies, so that could be an ideal choice.

Also, they mention that butterflies go nuts for these, so I may look into planting one myself!

FoodsGood Farm wrote:Hi Permies! long time reader first time commenter.

looking for a nitrogen fixing tree for my area (east coast of canada, bay of fundy, zone 5a) I have about 30 fruit trees planted so far in 3 different areas on my farm, Apples, Pears, Plums, Cherries, Peach and Apricot. I am planting in guilds designed to come together over time, but I still haven't nailed down the large N fixing chop and drop element.

I have grown out honey locust collected from trees my area but the spikes are pretty gnarly. I am a barefoot farmer so that has been ruled out for me, gonna dig up the ones I already have planted in zone 2 and move then to a zone 4 area and hope that they don't grow back form any roots I miss. I have a few sea buckthorns bought from the nursery, but they haven't really done very well so far on my land. I started a bunch from seed this spring so hopefully they will be more productive that way. I have a couple of siberian peashrub which look promising, but its too early to tell.

I guess I am really wondering if anyone in my climate has had success using speckled alder as the n fixer? it grows in the wetter spots of my site and is the first to take over old fields in this area. I know my dad and grandfathers would think I was absolutely nuts for actually planting speckled alder, but maybe that is the sign that its the right thing to do from a long term soil building standpoint? following natures signs instead of fighting them?

I'm confused, are you looking for a Nitrogen fixing tree or plants for chop and drop? you mention both as if they were interchangeable, which they aren't.

Chop and drop refers to items like alfalfa (Lucerne), clovers, comfrey, and other well known nitrogen fixing plants.
Trees don't chop and drop usually because of the heavy trunks, which would need to be chipped up. Just like the other rhizobium using nitrogen fixing plants, the trees use nodules to house the rhizobium and that means to get the maximum benefit to the soil you would need to kill the tree.
It is a lot faster to grow the annual types for chop and drop where you get both the N and the mulch layer (which will decompose into the soil surface and work down towards the second horizon).

If you are looking for tree type N fixers for your area I'd go with the Betulaceae family and particularly the Alnus genus(alders are a member).
If you go to ontario native trees you should be able to find the trees that will do best in your area.

Redhawk