Honey Locust - nitrogen fixing? Other uses?

Hi Stefan, thanks for coming to the forums at Permies. I look forward to seeing the whole DVD, but so far have just seen the shorter teaser video a few months ago.

I believe in that video that you were using Honey Locust as one of the trees in your permaculture orchard, largely for nectar for pollinators, and to block same genus trees from being too close together for pest insects.

I know there is some controversy about whether Honey Locust fixes nitrogen (or less of it), since it doesn't produce root nodules, but is a legume. What's your experience on this?

When hearing Mark Shepard present back in February 2014, I was surprised to hear him say that he'd planted plenty of Black Locust in his plantings, and not noticed a difference in terms of assisting nearby fruit trees, though he said there was a measurable difference on grass and herbaceous plants near the locusts. He also mentioned the important fact that locust thorns have burst a lot of tractor tires on him!

My overall question is: have you noticed nitrogren-fixing trees affecting crops/tree health, and if so, which ones seem to have the most effect?

I love locusts - I think because they have some amazing qualities (nitrogen-fixing, rot resistance (Black Locust), huge pods for forage (Honey Locust), soap substitute (I think it's Chinese Honey Locust), Caspian Locust (sweet sap), but also have some management challenges (large thorns, fast-spreading with suckers).

Thanks.

Rob I don't see where your from. Honey Locust are our hardest working trees. As per Permaculture design the elements you use should have 3 functions. Here's what honey locust do for us:
1) FIX NITROGEN. I don't care how but they give us a commercial yield on our fruit trees so I assume they are doing something in that department.
2) In BLOOM nothing we grow beats honey locust for straight power of attracting insects. It's just amazing the insect in those trees in bloom. Not just bees, everything that sips nectar and seeks pollen is in there.
3) Once the trees are tall enough (12-18') we use them as LIVING POSTS. Attach our frost protection wire and pipe on to them.
4) LIVING STAKES. We grow our annual vining crops up onto them (peas, beans, cucumbers) in the early years and are now switching to our perennial vines (grape and hardy kiwi) to grow up them.
5) MULCH the leaves fall as leaflets and make a great mulch that quickly turns to compost under the trees. It allows many seedlings to sprout and grow beneath them serving as a LIVING NURSEry tree.
We operate as a members only U-Pick. Black locust with it's thorns is not a crowd friendly tree. All our honey locust are the thornless variety 'inermis'.
Most effect??? We are trying all nitrogen fixers and have not seen a noticeable difference so far. Time will tell?

Thanks Stefan - I didn't realize I hadn't put in my location info - near London, Ontario - Zone 6a - so just 'around the corner' from you.

I admit to liking the spikes on the locusts, even though I have kids. I am very small-scale, and prune off the low spikes and spiky branches. Actually, I'm drying them and saving them for possible use as little tacks! I can see how thornless is very important for pick-your-own, or if using wheeled machines nearby.

I love the idea of training kiwis/grapes up them, and combining (like Martin Crawford) coppicing with this. In fact, though my black locust are only 3 years old, I'm going to plant a couple of Acinidia polygama (Siver Vine Kiwi) to climb them - as they are less vigorous growers than Hardy Kiwi. Hopefully will get those planted tonight. The rush of the season!

Rob

Rob, I have the thorny honey locusts all over my land and they are brutal! Like you I try to manage them by trimming the lower branches and spikes. When clearing out all the underbrush under one huge one last fall I noticed there were several small wild passionfruit vines growing along the ground, which I left alone. This spring I looped them over the remaining lowest branches above my head height, and they are now vigorously climbing up the tree.

That's awesome Dan - I'm constantly looking for opportunities to make similar 'deals' with nature.

Thanks so much for this post guys! I too have wondered if the same benefits could be had from one of my favorite trees...honey locust, as can be had from the black locust! It's great to see such high praise for this tree!

I might be a little lost between topics. I thought someone had asked about the size of honey locust trees and crowding/shading some of the other trees. I was looking forward to the answer but now I can't find the thread or question.

Hi Mitch: Wikipedia says Honey Locust range from 66-100'. I can't say I've ever seen one that big in my area - where they are just barely native species at the very north of their range. I see them up to about 30' or so. I imagine those tall heights are pretty old trees in the south of their range.

Like other locusts, their canopy cover is nowhere near as dense as other hardwoods - they have a kind of checkered shade effect.

That said, I think of them as something I will prune and coppice. In my case, I have planted them close to fruit trees, and each year prune lower side branches (for chop and drop mulch - though watch the thorns!), leaving them with a 'fuzzball' at the top of the trunk. This way they don't shade the fruit trees much (they will in a few years be much taller than dwarf fruit trees - as they grow fast). Every ten years or so, you can coppice them to the ground, and train a new 'post'. Every time you prune, the tree self-prunes its roots, releasing more nitrogen for the surrounding trees. Eventually, unless you prevent it, your fruit trees will shade out the locust.

Note that I've only tried this so far with Black Locust, and only for a few years, but Martin Crawford uses this technique with nitrogen-fixing trees (Geoff Lawton too - I think it's him that calls them 'nurse trees'). I expect Honey Locust would respond the same way to coppicing, but don't know for certain. Also - as noted above, it is said not to have as much nitrogen-fixation.

Rob Read wrote:Hi Mitch: Wikipedia says Honey Locust range from 66-100'. I can't say I've ever seen one that big in my area - where they are just barely native species at the very north of their range. I see them up to about 30' or so. I imagine those tall heights are pretty old trees in the south of their range.
Note that I've only tried this so far with Black Locust, and only for a few years, but Martin Crawford uses this technique with nitrogen-fixing trees (Geoff Lawton too - I think it's him that calls them 'nurse trees'). I expect Honey Locust would respond the same way to coppicing, but don't know for certain. Also - as noted above, it is said not to have as much nitrogen-fixation.

Yes Honey locust is an excellent coppice tree. Most of it's nitrogen release happens by pruning and subsequent root sloughing or so they say.

Oh great I didn't realize honey locust coppiced well!