What is the point of Nitrogen fixing trees without Inoculant?

Trace, I feel as if the “Nature will take care of it for you” is encompassed by the part of my quote where I talk about being advised to do nothing. Happens I *agree* with the advice, but it’s still a thing we do at permies that can be, and often is, frustrating to people looking for specific information.

The deeper wisdom being that permies.com is not an encyclopedia or a search engine or a vending machine. You can’t just put in your coin and pull the lever and get a nice clean answer; most of us here aren’t LARPing as research librarians. It’s more like climbing the proverbial hilltop to consult a gang of argumentative gurus. They will give you information they think you need, which is not necessarily the information you wanted. And the further it seems to them you might be from a good path as they see it, the less forthcoming they are with practical information about the path you are actually on. Instead you will be showered with maps.

I should be clear: I have empathy for the frustration that can result from this. But I don’t think it is, overall, a bad thing. I do think we should strive for self-awareness on the matter.

Pearl Sutton wrote:Has it not been studied?  Or is there data out there so tangled up we can't find it? Might be an interesting project for someone to see if there is uncollated data out there that could be collected into one place where it could be found (and posted to Permies!)

Like a lot of questions of interest to permaculturalists, I think the answer is a mix of "not been studied" and "too hard to study because too many variables" and "lots of data out there buried in random scientific papers that are hard to find or not on Google".  But in this particular case there is an overlayment of assumption; botanists in general are divided into "lumpers" and "splitters" (an old taxonomical debate) and the "lumpers" tend to assume that similar species have similar characteristics, which is often true.  Somewhere early in the development of permaculture thinking, the notion of "legumes=nitrogen-fixing" got planted very deeply, and though I think the heavy hitters must have always known better, an enormous number of derivative permaculture writers and teachers have passed on that simple equation as if it were always true gospel, when in fact I'm not sure if it's true even fifty percent of the time where trees are concerned.  (My own percentage when it comes to "take a species and try to confirm if it's a nitrogen fixer" is much worse than 50%.)

All that said, we've got an active thread right here on Permies.com right now where a member is discussing making a website to pull together more of this information.  

The reason we did not directly answer his first question is: as a rule there are never really easy answers for WHY questions.

Case in point, why did World War One start? Sure, there can be the explanation that an assassination started it, but that was just the straw that broke the camels back; the real answer as to why World War One started were many reasons.

This applies to almost all WHY type questions. They are really hard to answer. Sometimes in matters of Permie related things, there is science that backs it up, but that requires money to research, and there must be a reason why an entity (government or private) would investigate into it. That has its own problems unto its own however.

But in todays Google World, people want instant, and concise answers, and with why questions that just does not always happen. But its good, it keeps us on our toes, keeps us experimenting, probing and learning. Sometimes the most important thing about a why question is not the answer, but rather the research done along the way.

…
As to why my tree is growing so well? I suspect when it was planted, due to the fact that this soil was literally virgin, no inoculants were needed because thousands of years of forest dander build up was more then enough nitrogen to feed the growing tree. Keep in mind, my farm was cleared in the year 1800 (not in the 1800's, but in the year OF 1800). About 200 years ago when this became a homestead and this tree was planted.

Travis, I consider your big farm experience extremely relevant.  Home gardens and small food forests are relatively easy to make lush and fertile because the ratio of inputs and labor to land is so high.  But to make a big farm work is a whole new level of challenge, and I would love to hear more about your experiences of attempting to do permaculture friendly farming.

As far as the NFT (Nitrogen-Fixing Tree, getting tired of spelling it out everytime) on your property, 200 years is 3 lifetimes of waiting, and there's still no assurance it is fixing nitrogen.  My legume annuals are growing just fine despite the lack of nodulation.  I've been avoiding fertilizing them to encourage nodulation, but they are still growing.  I am sure they are not fixing nitrogen though as these species are well-known nodulating legumes.

Further complicating the issue, and this will be of interest to Dan, is that there exist non-nodulating NFTs.  I've gone way past the 1 hour google search by now, and started digging into excerpts of books and scientific papers on the topic.  Good news is some of those native NFTs and shrubs on Dan's property might be fixing nitrogen after all despite the lack of nodules. Bad news is it's pretty much impossible to tell without scientific equipment, making a fuzzy situation even fuzzier.

With scientific equipment, apparently they can determine whether the nitrogen in the foliage is coming from the atmosphere or the soil based on N15 levels.  There's also a different test they can do to try and see if nitrogenase (the enzyme that enables nitrogen-fixation) activity is present.

Ben Waimata spoke about a poor experience attempting to grow
frequently recommended permaculture NFTs like the South American Tipuana Tipu and Mimosa Scabrella in New Zealand soil.  The appropriate bacteria simply may not exist across continents.  I think that's a very important consideration when choosing which trees to plant, and a consideration that hasn't been emphasized in many of these permaculture plant lists circulating around.  Importing a scoop of soil may be illegal in some areas.

Finally, despite the existence of non-nodulating NFTs, it seems like  the heavy lifters, the NFTs that fix lots of nitrogen, are indeed nodulating.  If you are seeking to inject fertility or produce lots of biomass without a lot of inputs, I think it's very much worthwhile to seek out nodulating species and ensure they are properly inoculated.

Jason Yoon wrote:Further complicating the issue, and this will be of interest to Dan, is that there exist non-nodulating NFTs.  I've gone way past the 1 hour google search by now, and started digging into excerpts of books and scientific papers on the topic.  Good news is some of those native NFTs and shrubs on Dan's property might be fixing nitrogen after all despite the lack of nodules. Bad news is it's pretty much impossible to tell without scientific equipment, making a fuzzy situation even fuzzier.

With scientific equipment, apparently they can determine whether the nitrogen in the foliage is coming from the atmosphere or the soil based on N15 levels.  There's also a different test they can do to try and see if nitrogenase (the enzyme that enables nitrogen-fixation) activity is present.

Yes, I was aware; in the case of one of the dominant trees in one area on my property (honey locust) there exists precisely one study that yielded ambiguous results on the question of whether it fixes nitrogen without nodules.  

I was trying to leave the question of non-nodulating nitrogen-fixers out of the discussion because it seemed like they would add to the complexity in a situation in which you were asking for quick simple answers.  I didn't see how "Your trees without nodules might be fixing nitrogen anyway, but if so there's no practical way for you to find out, and probably not as much as you would want" was going to be the answer you were looking for when you were questioning why you would even want these trees.

It's hilarious (he said with a sardonic tone) how the universe likes to rip strong statements straight out of your mouth and stuff them right back down your throat.  Earlier today in this thread I wrote:

Dan Boone wrote:I would no more buy an inoculant product for my land than I would buy magic beans from a shady character I met on my way to the market to buy food for my starving family.

Another thing I do not buy is bagged powdered fertilizer; this is primarily due to the expense being beyond my budget, secondarily due to the fact that I don't trust its origins, and tertiarily due to the belief that I don't need it, having enough land that, one way and another, I can rob Peter to pay Paul and keep enough fertility in my small bits of garden.  However, at least some of the gardening disappointments that I casually chalk up to being a "bad gardener" are probably due to fertility deficits and imbalances, and I am not a complete zealot about outside inputs; I've always been willing to buy small quantities of fertilizer, usually for a buck at some garage sale or other.  

So, having said what I said this morning, I trotted off to a local retailer where I discovered an extreme fall clearance underway including many 8lb bags of so-called "organic" fertilizer (I do not credit that labeling with being in any way meaningful) marked down from ridiculous would-never-look-at-it prices to $1.00 a bag.  And at that price, my resistance to off-site chemical-ish fertility amendments begins to melt somewhat, and some dozen bags fell into my cart.  (I'll worry later about precisely how careful I need to be in actually using the stuff.)  Only once I got to my vehicle did I notice that the entire back of the bag was taken up with serious mumbo-jumbo about the biological package of bacteria and fungus incorporated into the product.  These are scattershot in the extreme and might be entirely fictional -- certainly I would not have paid a dime extra for them -- but at least some of the mumbo jumbo seemed to be indicating that some common inoculants for legumes were included.  And thus did the universe make a fool out of me today.

Dan: Too funny!

I don't currently buy mulches, compost, or fertilizers for my garden. But a decade ago, I did. And the packaging said that there were however many billions per gram of living propagules of a wide range of species of microbes, including all the commonly talked about microbes for soil fertility and plant growth. I'm pretty skeptical that they could have actually measured something like that for each species, but whatever. For all I know, the success of my garden might have little to do with my current practices, and a lot to do with the inoculation that I bought from The Conglomerate about a decade ago.

Bwah. Ha. Ha!!!

Jason, I am glad your frustration and impatience are for such altruistic intentions.

I bet you would already have a more specific and useful answer if you posted your location, at least a general region. This is because I would recommend a locally native nitrogen fixator. If in the Pacific NW of North America, I would recommend Red Alder, and I would bet other alders throughout north america fixate nitrogen as well.  Many early pioneer species have beneficial nitrogen fixating and soil building qualities (i.e. horsetail accumulates carbon and micronutrients in river sand). One benefit of natives is you would not have to buy inoculant or the plant. Also, you could start many of them for little cost. If you are worried about "waiting for nature,"  you could get some native soil from either the tree you dig up [ethically, ie thinning a thicket of seedlings], or if you are into buying local natives rather than foraging and propagating them, you could get a little soil and duff from a place your nitrogen fixating tree species lives. You don't need much.

That hopefully somewhat specific and helpful answer given, the wise folks telling you to be patient and let nature reward your good permaculture practices in good time are not wrong. If you are following the permie practice of enticing birds into your garden, you are accumulating nitrogen and other nutrients. Same goes for most other life, including insects we often consider pests. Fungus can fixate 200lbs of N/acre in forests that are too shady for native nitrogen fixating trees, and this is all the fastest growing forests on Earth (old growth redwoods) need, though Nitrogen is their limiting growth factor.  Any trees supporting animals and other life in their canopy and roots, accumulate nutrients and slowly spreading them downstream with rain and dew drop.   Evergreens can increase the phosphorus content of rainfall that weeps downstream by 25x (Mollison). If you are keeping animals, put them uphill of the garden and they will feed it.

I also would bet nitrogen fixators attract animals that then spread their inoculant, a bit like bees and flowers. Considering how nitrogen is an essential component of protein and chlorophyll, species as well as entire ecosystems would be evolutionarily rewarded for supporting nitrogen fixation. I would bet every lush ecosystem on Earth has nitrogen fixating support species like birds, insects, fish and other animals that help transport nitrogen fixating bacteria and fungus to recently disturbed and erodable/leachable land. I bet pigs carry a huge amount of good microbes on their tusks/snouts and in their guts, as do bears. The easiest and most successful way to plant many native plants to north america is as a part of bear scat. On an ever broader scale, ecosystems that support nitrogen fixation, just like those which support pollination, would be more stable and therefore stabilize land formations that are conducive to these ecosystem functions. As you probably also know already, mature trees can create and moderate their own weather to a large extent given enough range and time. This is why you are right about the difficulties of so many segmented small lots for natural processes of self-restoration to occur. However, if you do have a small lot, this allows you to concentrate a lot more on it and would better justify the time and energy collecting nitrogen and other soil building from locally abundant waste streams (ie neighbors' leaves and brush piles, ideally containing some nitrogen fixating tree material).

Either way, nature is not passive and ecosystems, being complex adaptive systems, express a kind of problem solving akin to intelligence based on natural selection. Over time evolution has selected for life which creates or supports favorable conditions for its self-perpetuation.

It's going to be fine, we all will be part of the singularity again soon enough. In fact we already are and just forget that reality from time to time.

Alot of permaculture is about it depends.

So I am going to ask the original poster to give more specific details on the six W (What, where, when, who, why, how).
How many different type of nitrogen fixing legume are you looking for?
Do you have a specific height requirement?
How about rainfall distribution and amount, summer heat, winter cold, soil type?
Are you in a tropical/subtropical/temperate region, can you list a few of the easily recognizable trees that grows around you (Eco-region/continent/country/state/city)?
With the above info we would be more likely to give you a more specific list of legume for your specific condition.

Also I am going to assume (I know, already a stupid idea):
A) that you have a list of legumes that list how much lbs or nitrogen it fixes per acre and you would like to plant them,
B) but you have some already established legumes that you WANT TO CULL because you think they are less than optimum.
And so you are asking for some 'permission' to cull them and plant something better

But maybe you are not looking for a specific list or trying to replace some less optimal legumes that are on site
and instead you are just trying to raise general awareness that not all legumes are equal or even fix any type of nitrogen or if they do not all fix it by the easily recognizable pink root nodule

You mentioned that you did some google sesrches and didn't get any good result. Which species of legume do you have planted that is suppose to have noodles with nitrogen fixing bacteria but doesn't seem to be working. Maybe if you list it someone will be able to figure out which group of bacteria will colonize it and a vendor that sells it and then a way to spread it to your existing legumes cheaply and relatively quickly.

Also there is free living nitrogen fixer and then there is the traditional symbiosis legume-nitrogen fixing bacteria but between the two we have associative nitrogen fixing bacteria
https://openprairie.sdstate.edu/cgi/viewcontent.cgi?article=1688&context=etd

Jason,

I am going to put words in your mouth. This seems like as much an experiment to you toward upscaling as a practical motive.

If that is not so, disregard please.

Scale matters. When I had a tiny area, I think it would make sense to try to kick start it with some nifty inputs. I have used commercial innoculants on small areas and with plants that need a different rhyzobia than the current occupants. I do think it helped. I don't see myself ever doing it again. As an example I tried to grow some alfalfa and trefoil here. This is not a tree and there are well-defined associations. I slurry inoculated them and seeded them out. They lasted a year, and were overtaken by native red clover and some little vetch.

Trees are no different. I would look at what is invasive, because that is a sign that the symbiosis in your climate to include soil microbes is good. There are too many variables beyond simply applying the correct inoculant to "fix". There are soil chemistry issues, associated fungi, heat/humidity issues, etc. Those affect the soil as much as the tree. I have been able to get stuff to grow as an act of will, but just keeping it alive has not turned into thriving. Having novel plants is fun and challenging, but in my experience not very productive, which makes me less inclined to keep doing stuff. When you get some space, you can afford some misses, and you will have some surprising successes. On a small scale, it is much more challenging, because you have fewer niches.

If you are in Cali, and want to grow carob or something, find someone growing it and see the whole picture, soil type, sunlight, mulching etc. If you can steal some starter soil, you are way ahead! For a small area, you may be able to get a potted specimen that already contains microbes. Microbes expand exponentially,  as long as they have a scaffold to do so.

In terms of the argument about what is nitrogen fixing and what is nitrogen cycling, that seems to be a pretty muddy picture. For instance my mulberries have about the same amount of nitrogen by weight in their leaves as the honeylocsts. My suspicion is that often nitrogen loss is the bigger driver than nitrogen fixation. I look at the soil under the plant to see if it is fluffy and full of life and whether the grass is deep green or stunted. Think of why you are placing that plant, and see whether it seems to derive that function in your biome.

Legume nodule size and color will change depending on the time of the year.
They will big and "RED" during the vegetative stage of the year. (because the plant wants/need more nitrogen).
Once the plant flowers and "stop" growing and start putting all of it's energy into fruit-seed growth vs root or vegetative growth. The noodles will "starve" once the plant sugars are redirected and they will get smaller and less RED/PINK, until that fruiting phase of the plant is over for the season.

Here is another post talking about nitrogen fixing trees, that might have a bit of relevant info.
https://permies.com/t/94673/Nitrogen-Fixing-Shrubs#776760

S Bengi wrote:Legume noodle size and color will change depending on the time of the year.
They will big and "RED" during the vegetative stage of the year. (because the plant wants/need more nitrogen).
Once the plant flowers and "stop" growing and now flowers and start putting all of it's energy into fruit growth vs root or vegetative growth. The noodles will "starve" after the plant sugars are now redirected and they will get smaller and less RED/PINK, until that part of the plant growth phase is over.

Here is another post talking about nitrogen fixing trees, that might have a bit of relevant info.
https://permies.com/t/94673/Nitrogen-Fixing-Shrubs#776760

What I have read, maybe bull?, post season pull up plants and examine nodules.

"The co-inoculated P. gonoacantha plants produced a higher shoot weight with D. heterogama and BSP1 strain. This combination was very promising for P. gonoacantha inoculation in the future for seedlings.
These results stress the relevance of studies of inoculation in tree species used in reforestation and land reclamation."  - out of the summary (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5221347/)

Where can it be bought or is this a study that went no where?

Here is a vendor that sells bacteria cultures.

Most universities also have some available if you contact them.

Also the EL Group seems to be able to inoculate all the less domesticated legumes across different sub-families of legumes.
https://hancockseed.com/el-type-inoculant-6-oz-bag-21.html

Find a botanical garden that has the species you have planted and contact them requesting some rhizosphere soil to inoculate yours with.

As a rule, nitrogen fixing bacteria tend to shut down when soil nitrogen levels are moderate to high. If your soil has a lot of nitrogen in it, they aren't really needed and won't associate with roots or form nodules.
You can "starve" your plants of nitrogen by mixing sawdust or other high C:N ratio material into the soil. This will last for weeks or months or even years, depending on how much material is incorporated and lignin content. Sawdust is practically pure lignin, making it a good choice.

To determine sawdust requirements, first determine the quantity of nitrogen in the soil solution from soil test results. Convert ppm N to lbs N/acre by multiplying by 2. Multiply soil solution nitrogen (lbs N/acre) by 1.375 to determine the number of cubic yards of sawdust to incorporate per acre and scale it to the amount of area you'll be planting. This will bring N levels in the sawdust-treated soil down to virtually nil for 8-12 weeks, after which, available soil N will slowly start to rebound.. Adding more will last longer.

This won't happen if the sawdust is used as a mulch. It must be incorporated into the soil.
Be careful not to incorporate sawdust in soil that will be planted with non-legumes!

The one thing I have not seen mentioned here, is that there are nitrogen fixers that have no nodules. Carob is one, I found a paper about it on this site somewhere, but I forgot where.