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Soil biology question about organic fertilizers

Dan Fish

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Hi,

I am reading up on Redhawk's Super Soil Threads and I keep getting distracted by a small but nagging question. If someone has a moment to answer that would be great!

I am learning about living soil and how plants, their exudates and various soil organisms combine to provide a non-leaching supply of nutrition. I also understand why a chemical version of this same nutrition would leach away after all the consumers are full up and can't use anymore of it (right away).

So here is my question. What about organic fertilizers, for example Dr. Earth Tomato Blend? (I picked that because that is what I have used in the past) They would also leach away after all the plants and organisms get their quick fix correct? Am I correct in assuming that the only differences are that they; contain less "potency" and thus less is gone unused? And that any leaching that does occur isn't spreading salts and whatnot, just somewhat wasteful?

Sorry, I have one of those "special" brains that won't let me concentrate with a nagging question that keeps popping up!

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Trace Oswald

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Dan Fish wrote:Hi,

I am reading up on Redhawk's Super Soil Threads and I keep getting distracted by a small but nagging question. If someone has a moment to answer that would be great!

I am learning about living soil and how plants, their exudates and various soil organisms combine to provide a non-leaching supply of nutrition. I also understand why a chemical version of this same nutrition would leach away after all the consumers are full up and can't use anymore of it (right away).

So here is my question. What about organic fertilizers, for example Dr. Earth Tomato Blend? (I picked that because that is what I have used in the past) They would also leach away after all the plants and organisms get their quick fix correct? Am I correct in assuming that the only differences are that they; contain less "potency" and thus less is gone unused? And that any leaching that does occur isn't spreading salts and whatnot, just somewhat wasteful?

Sorry, I have one of those "special" brains that won't let me concentrate with a nagging question that keeps popping up!

I look at the difference in terms of processed vs unprocessed. Chemical fertilizers are broken down to the point the are utilized almost immediately by the plant. Organic fertilizers are not. They need to be broken down by soil life and are passed on to the plant much more slowly and so, last much longer.

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Eric Hanson

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posted 4 years ago

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Dan,

I think I understand the question you are getting at. And I think the short answer is that most of the issues that arise from synthetic fertilizers can also come about from organic fertilizers. That being said, organic fertilizers are generally slower and longer acting, includes trace minerals and tend to get along with soil organisms better.

For the sake of discussion I will try to compare blood meal to a synthetic high nitrogen fertilizer. Blood meal used to be my favorite fertilizer. It was organic, worked fairly quickly, turned my tomato plants dark green and generally lasted a while. But in my opinion the main problem with basically any fertilizer (especially nitrogen fertilizer) is that it disrupts the chemical relationship between plant and soil organisms.

As RedHawk has articulated, healthy soil has a healthy population of soil microbes that have established a healthy relationship with the crop plants. The problem is that plants are greedy and will take nitrogen from wherever they can find it. If the plant gets a sudden dose of nitrogen from either synthetic nitrogen or blood meal, it no longer needs nitrogen from microbes and microbes no longer get root exudates and especially the two don’t work together. It’s almost like the plants and microbes get a divorce because one or the other is cheating and just no longer needs the other. The problem then is that once divorced, they don’t quickly get back together again.

I have taken to planting exclusively in woodchips inoculated with wine cap mushrooms. The wine caps intertwine with the roots and they plainly grow together in a true symbiosis. My best crops have been grown in association with mushrooms. I am continuing to introduce more microbes to the mix.

Dan, I used to look at soil fertility as NPK levels. I now see fertility as a matter of soil microbes and soil life. I only very rarely add fertilizer (organic of course) and only when I first transplant something into woodchips that have not broken down yet. Other than that specific situation, I rely on soil microbes to provide soil fertility. I try to grow plants and microbes together.

So in the short term, fertilizers will help your plants, but that creates a sort of chemical dependence in which the plants need more fertilizer to accomplish the same level of fertility.

Dan, I hope this helps and doesn’t confuse, but if you have any questions, please don’t hesitate to ask.

Eric

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Trace Oswald

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I guess we should define "organic fertilizer". I use the term less for a product I would buy than for something like manure. I did make a batch of Steve Soloman's recipe, complete organic fertilizer to try this year on some new beds I am making. I will probably use it again in spring. The goal of course is to build soil to the point that it is unnecessary but I have no problem using it in the meantime. I will probably always use products like Sea 90 to ensure that the minerals are available for plants.

I definitely agree with Eric that long term, building soil fertility is the way to go.

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Eric Hanson

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Trace, Dan,

So I have a working definition of organic fertilizer, but it is not perfect and feel free to poke holes where holes need to be poked.

At present my overarching mission for improving my fertility (read this as organic fertilizers) is I refuse to add any fertilizer unless it comes from my land. I still accept lawn clippings from neighbors if they are chemical free and the same goes for leaves, but by and large I grow my fertility. Comfrey is an important part of my home grown fertilizer. My woodchips are aggressively decomposed by wine cap mushrooms and the compost is extremely fertile. On occasion I will use urine, but that is mostly used to provide a quick dose of starter fertility before the woodchips break down.

The ultimate goal is that I provide my own fertility. I am still experimenting with bringing in certain soil bacteria, mostly nitrogen fixing bacteria for legumes, but once added they take care of themselves. And of course I will introduce new cover crops. I am wanting to add Austrian Winter Peas this year to pump in nitrogen and control weeds. I might do something similar with Crimson clover. But here I am growing the fertility.

I long ago stopped buying in fertilizer like 10-10-10. And by now, I don’t even like bone or blood meal because it feels like cheating. Basically everything going on in my garden is my own circle of life which includes death and decay. I really look at my gardens and want to see an active, healthy soil (or woodchip) biota first and then figure out how to get those microbes to feed my plants.

This is not a state reached overnight. It is largely aspirational. It is a goal I hope to reach someday, but I am well on my way.

Eric

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s. lowe

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I think that one of the main differences between synthetic and organic fetilizers is that most synthetic fertilizers are mineral salts. This causes two main issues, the first is that they are inherently highly water soluble which makes it easier for them to be washed through/over the soil and out of the zone where they were intended. The second I don't understand nearly as well but their nature (as a salt) seems to create an interaction related to osmotic pressure that allows them to force.their way into plant roots and makes excesses a very real concern. This can cause increased fungal and insect susceptibility and in extreme cases just outright kill a plant. A third issue is that many of these salts are harmful to soil life and thus tend to create a dependency cycle.

Organic fertilizers on the other hand tend to be more complex, molecularly, and tend to be less soluble. They tend to function more.by feeding the soil life than by forcing mineral ions into the plant. You can still obviously over do it of course, especially with nitrogen which is among the most mobile minerals.

Ultimately I do think that, unless you are practicing a fairly high intensity, monoculture, production style agriculture you can build your soil and garden up to the point where you don't require (many) outside inputs to maintain your fertility.

Dan Fish

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Fantastic thanks everybody.

And for once, I feel like I understood what y'all were saying! Look at me! I'm growing up!!!

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Douglas Campbell

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posted 4 years ago

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There are, however, limits.
N can be fixed from the atmosphere by microbe/plant consortia.
P can be mobilized by microbes, but there are soils which are simply P deficient.
Also,,interesting factoid: most of the N (~90%) in human populations is derived from chemical fertilizer (Haber process).
Human population is ~8,000,000,000.
Before ferilizer it was ~1,000,000,000 around 1900.
We could probbably do a bit better now, but those numbers imply a large population drop if we go without ferilizer.

s. lowe

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Douglas Campbell wrote:There are, however, limits.
N can be fixed from the atmosphere by microbe/plant consortia.
P can be mobilized by microbes, but there are soils which are simply P deficient.
Also,,interesting factoid: most of the N (~90%) in human populations is derived from chemical fertilizer (Haber process).
Human population is ~8,000,000,000.
Before ferilizer it was ~1,000,000,000 around 1900.
We could probbably do a bit better now, but those numbers imply a large population drop if we go without ferilizer.

I think if you factor in food waste and acknowledge that its not uncommon anymore.for.the highest yielding farms in a given county to be working without synthetic N it's pretty easy to recognize that the spectre of mass starvation if we decided to forego noxious chemistry in our food production is more industry propaganda than foregone conclusion

Rebecca Norman

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Douglas Campbell wrote:
We could probbably do a bit better now, but those numbers imply a large population drop if we go without ferilizer.

If all the nutrients from our excreta could be conserved and returned to the soil that is used to produce our food, it would be enough to produce the food to feed those same humans. This is simply the conservation of matter. Matter in, matter out, matter back in. It is a cycle like the water cycle or the oxygen cycle. Some nitrogen is lost to the air, but some nitrogen is fixed by plants and soil organisms. The rest of the nutrients are largely earth-bound, from what I understand, so they would largely remain in this cycle. Unfortunately your 8 billion humans currently turn almost all of their excreta into waste, breaking the cycle and necessitating artificial fertilisers.

But the original question of this post is intriguing. Is using dilute urine or compost leachate as a fertiliser much the same as using soluble artificial fertilisers? Is the divide really between soluble fertilisers and those that are combined with solid organic matter? Or between organic and artifically produced? Or something else?

My feeling, but I think it's just a hunch, is that soil containing plenty of healthy organic matter and soil organisms can handle, store and help plants utilise inputs of soluble fertiliser. But I don't know how true this really is.

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Eric Hanson

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Rebecca I largely agree with what you said. I do think that a healthy compost should have plenty of nitrogen for a growing plant. On the other hand, urine happens and it has to go somewhere and what better use than to fertilize a plant?

So I guess that having some urine even on healthy compost is good unless it breaks that microbe chain happening in the soil.

I really like to go back to a Gabe Brown video. His soil has multitudes of microbes supporting plant growth, but he does also include animal husbandry on his land in order to assist soil fertility. This means a lot of urine and manure. The manure becomes fertilizer somewhat slowly and brings its own microbes to the mix, but the urine is a very fast acting fertilizer.

Perhaps there exists an optimal balance between microbes and some additional nutrients (especially nitrogen) in the form of urine.

Eric

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Dan Scheltema

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Eric Hanson wrote:

I really like to go back to a Gabe Brown video. His soil has multitudes of microbes supporting plant growth, but he does also include animal husbandry on his land in order to assist soil fertility. This means a lot of urine and manure. The manure becomes fertilizer somewhat slowly and brings its own microbes to the mix, but the urine is a very fast acting fertilizer.

Perhaps there exists an optimal balance between microbes and some additional nutrients (especially nitrogen) in the form of urine.

Eric

Thunk and dunk (tm) is also an important part of Gabe's system. The cows (especially) trample the vegetation and shove it into the soil where it more rapidly decomposes. He repeatedly stresses the value of that over and above the urine and manure. (I love the way he gets all excited over how well a mass-grazed herd has trampled the pasture down!) Also, he points out the importance of the trampling of hay when he uses that for feeding too.

But this adds to your point.

I am wondering how weed tea (aka Dave's Fetid Swamp Water [DFSW] as David the Good calls it) plays in to this too. I am experimenting a little with that, and homemade "fish emulsion" separately, as boosts to growth on my startup garden. Long term I want to go towards good soil and away from adding "fertilizers" though. Looking for shorter term additions that won't hurt my progress towards long-term stability. Anaerobic vs aerobic bacterial environments, but the soils has both also. Should sort itself out, but would the former hurt the latter for a while? Hard to tell from the plants' behavior in the short run if the plants get a boost from the anaerobically formed additives. "Unless it breaks that microbe chain happening in the soil," that is the issue.

That would be an interesting experiment, to run side by side comparisons for a few years to see how the soil life compares later. One bed using aerobic compost tea, one using anaerobic weed tea, and a control, all three using proper compost. Maybe a fourth with "industrial" fertilizers for another useful comparison. And measure the outputs like Charles Dowding does with his ongoing experiment. I'm not the guy to do it though, since I have more in common with David than Charles. I am not terribly systematic. :)

Went fishing last evening to catch a few panfish to try under some pumpkin mounds... I think I have time for another round of Seminoles. At least enough time to see how they grow compared to the mounds without the fish. One-off short-term experiments, those I can manage! Hope the fish didn't spoil too fast overnight as they are sitting in a 5 gallon pail in the back of my car at the moment...

Eric Hanson

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Rebecca,

Regarding your first point, I imagine that urine, diluted or no, is helpful so long as it does not displace nitrogen fixing soil bacteria. This same principle probably applies to chemical fertilizers as well. Actually the term “chemical fertilizers” is something of a misnomer as many of the actual chemicals provided by soil microbes and organic fertilizers are the exact same as those in chemical fertilizers. But chemical fertilizers are easier to overdo than natural fertilizers and even natural fertilizers can be overdone. Back when I was using blood meal, I wonder if I was breaking the relationship between soil microbes and plants.

BTW, I am focusing on nitrogen because that is typically the soil nutrients highest in demand and lowest availability. Nitrogen can leach right into the air, but microbes can fix it right back in. Potassium and Phosphorus come from underlying rocks and are probably present but perhaps not in a useable form. Microbes can help with those nutrients as well.

I once had a garden with a bizarre phosphorus deficiency. I didn’t test the soil (I should have), but when I planted tomatoes, they barely grew and the leaves turned purple. It was absolutely bizarre looking—like a plant from another planet. I was oblivious to the phosphorus issue till I mentioned it to another teacher at my school who was also an avid gardener and far more knowledgeable than myself (I was just starting out). He told me that was a sign of phosphorus deficiency. A little bone meal later and the tomatoes perked right up and remained a nice, healthy green.

The reason for the phosphorus deficiency was in my bizarre soil. Actually I am not certain soil was the right term. Perhaps biologically deficient clay based medium would be better. The ground had been an old coal strip mine a few years before. I could actually dig up portions of shale and I tried to burn them (because why not, right). I could not get them to burn, it was extremely low grade shale and the strip pit was backfilled with huge volumes of mine tailings that was then covered with a thin layer of clay. This happened fairly recently so I am confident that soil biology had not become widely established. I am sure that there was indeed phosphorus in those rocks but the biology had not arrived yet to take advantage of the available phosphorus.

If that were not enough, part of my backyard had previously been a haul road that was covered by about 18” of clay. I was building a deck over that spot, hit the old road and it made a layer of pan look lick tissue paper. The only soil I have ever seen that was harder was caliche. I just could not pound a post hole digger through that stuff.

So that first yard was quite the challenge, but after I amended the stuff, it did grow a garden but at great expense in time and effort.

Rebecca, I strayed in my answer, but to bring things to a close, I think that as long as you still have working biology in your soil, some urine won’t harm anything. In fact, some urine might even help some soil microbes. But this assumes the microbes are not overwhelmed.

Eric

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Dan Fish

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Well dang, this thread keeps on giving. I am very curious now, exactly at what point would introducing too much "easy food" (for the sake of argument let's go with urine) into the soil biome cause it to break down? I don't expect anyone to have an exact answer of course.

Aside: I hear you Eric, with your struggle and eventual success. I am in the first year of growing my new garden and it's going way WAY better than I ever dreamed. I live in the tertiary channel of the ancient Yuba River. It used to drain the entire Great Basin and as a result it was full of placer gold. So people used to blast entire hillsides down with water and remove the top 200 feet of soil in search of it. The underside of that is what my garden is made of. Biologically deficient clay based medium for sure! But a truck bed of horse manure, some leaves and sticks, some char and two coats of aerated compost tea have proven to me that you can grow in ANYTHING as long as you keep it mulched. Except peppers. The peppers are not happy.

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Eric Hanson

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Dan,

I am glad that you don’t expect an answer as to how much urine is too much. I can only speculate, but I doubt that it is as simple as below such level is safe and above is too much. I strongly suspect that increasing urine gradually disconnects the microbes from the plants.

But before I dis on urine too much, nitrogen is good for a number of bacteria which in turn is helpful to many fungi, including the wine caps I find so important. In fact, when I initially started the wine caps I was encouraged and did add some additional nitrogen to help out the bacteria that wine caps need.

To make matters more confusing, when I start my woodchips, urine jump starts the decomposition while the fungi get established.

So obviously some level of urine is going to be beneficial. While I was getting comfrey established, I gave it quite a bit of diluted urine. The dilution was not to weaken the strength, but simply to make the urine spread further. I have 6 comfrey plants and 4 got the lions share. I stopped giving urine about 2 years ago but those 4 plants still dwarf the 2 that did not get the urine, so the urine continues to have an effect. Today, all comfrey plants have been heavily mulched with woodchips and this spring were inoculated with wine cap spawn. We will see how that works out in the long run.

So Dan, I have no great answers, only more questions.

Eric

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s. lowe

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Dan Fish wrote:Well dang, this thread keeps on giving. I am very curious now, exactly at what point would introducing too much "easy food" (for the sake of argument let's go with urine) into the soil biome cause it to break down? I don't expect anyone to have an exact answer of course.

My understanding is that too much nitrogen added will break the natural nitrogen cycle by eliminating n fixers and stopping the plants from releasing exudates.that summon nitrogen from the soil.biome. this basically creates a dependency that will.show. up as a nitrogen collapse of.the N is not supplied by you.

Eric Hanson

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S,

Yep, that about sums it up as I understand it. You said it much, much more succinctly than I did.

Eric

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s. lowe

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Another point that I'd like to add to this conversation is the destruction of soil carbon. The liberal application of nitrogen will cause a commensurate release of soil carbon. The carbon in our soil is the "skeleton" of the living soil that provides stable structures for the dynamic biological populations to exist within. My understanding is that this is primarily a problem with the nitrogen salts as it stimulates soil biology to a fever pitch in which they consume soil organic matter (and respire that stable carbon as CO2) faster than of can be replaced. This is also called composting and is one reason that you can, quite literally, burn plants with excessive N applications. This effect is buffered with organic fertilizers because there is almost always a complex of nitrogen and carbon (a protein) that is the source of organic N.

Yet another thing to consider when adding nitrogen, my experience has been that plants that contain excess nitrogen are also much more prone to fungal disease. I assume this is because there is free nitrogen stored in the plant tissue in some way and it provides a high energy food source for the fungal pathogens. This is a problem with organic fertilizers just as much (I assume) as it is with synthetic.

This thread has honed in on N , sensibly since it is the primary element that is indicated by "fertilizer". But the other big one is P or phosphorous. The problem with synthetic phosphorous salts is that they act as fungicides and decimate soil fungal populations (in fact all of the certified organic soil fungicides I have ever seen are phosphates).

Phos access is almost always a problem of biology, it is often inaccessible without a good deal of biological activity. Ironically, heavy synthetic phos additions inhibit this biological activity and virtually guarantee that the soil phos will be no more available next season

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s. lowe wrote:Another point that I'd like to add to this conversation is the destruction of soil carbon. The liberal application of nitrogen will cause a commensurate release of soil carbon. The carbon in our soil is the "skeleton" of the living soil that provides stable structures for the dynamic biological populations to exist within. My understanding is that this is primarily a problem with the nitrogen salts as it stimulates soil biology to a fever pitch in which they consume soil organic matter (and respire that stable carbon as CO2) faster than of can be replaced. This is also called composting and is one reason that you can, quite literally, burn plants with excessive N applications. This effect is buffered with organic fertilizers because there is almost always a complex of nitrogen and carbon (a protein) that is the source of organic N.

Yet another thing to consider when adding nitrogen, my experience has been that plants that contain excess nitrogen are also much more prone to fungal disease. I assume this is because there is free nitrogen stored in the plant tissue in some way and it provides a high energy food source for the fungal pathogens. This is a problem with organic fertilizers just as much (I assume) as it is with synthetic.

This thread has honed in on N , sensibly since it is the primary element that is indicated by "fertilizer". But the other big one is P or phosphorous. The problem with synthetic phosphorous salts is that they act as fungicides and decimate soil fungal populations (in fact all of the certified organic soil fungicides I have ever seen are phosphates).

Phos access is almost always a problem of biology, it is often inaccessible without a good deal of biological activity. Ironically, heavy synthetic phos additions inhibit this biological activity and virtually guarantee that the soil phos will be no more available next season

Dan Fish

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Awesome thanks again. I have been out for a few days but have not lost interest in this thread. Especially now that you mention phosphorus! According to my soil sample the level of P in my soil is extremely low. (Insert the standard comments about living soil vs chemical fertilizers here). But I would still feel better if someone could address P in this discussion a little bit more. Is there a fungal-safe method to increase phosphorus and avoid the dependency we are discussing? It doesn't have to be immediate or surface applied. I plan on digging my beds after this season and incorporating a lot more organic matter. I knew I needed to do it but just didn't get to it. Anyway I can add anything then and following that never have to dig again!

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James Freyr

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Dan Fish wrote: Is there a fungal-safe method to increase phosphorus and avoid the dependency we are discussing? It doesn't have to be immediate or surface applied. I plan on digging my beds after this season and incorporating a lot more organic matter. I knew I needed to do it but just didn't get to it. Anyway I can add anything then and following that never have to dig again!

Hey Dan, may I suggest rock phosphates as a safe and gentle way to add phosphorous. There are several kinds out there, like soft rock phosphate, hard rock phosphate and a couple others if I recall correctly. It's rock granules and dust, and the phosphorous will become available through soil bacterial and fungal activity. Some of it will dissolve from mild carbonic acid, made when CO2 released from some soil microbial activity combines with water, and this will dissolve a little of that rock phosphate. It gets a lot more complicated than that, but rock phosphates are pretty stable and won't dissolve and runoff the surface or leech through the soil.

"Study books and observe nature; if they do not agree, throw away the books." ~ William A. Albrecht

s. lowe

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James hit on the simplest, cheapest option for soil safe phosphate. The critique of rock phosphate is that it's not a renewable resource, but it's an ag standard for sure. The other most accessible option is high phosphorus bird/bat guano, it's much more accessible for plants but has its own environmental costs.

The most interesting option that I've found is a dairy manure digestate. In reality many manures are good sources of phos but this digestate is supposed to be very available and foster the type of biology that makes innate soil phos more accessible over all.

The other option is to invest in biological inputs of phosphorus mobilizing bacteria and fungi. I think that most/many mychorrhizae facitate phosphorus uptake and there are many innoculants available. There are also some fairly new bacterial innoculants that specifically target phos uptake. My understanding is that any heavy clay soil has all the phosphorus you could ever use if you had the biology to access it

Some advice I'd offer to anyone looking for organic input options is find out of you have a small garden store nearby that caters to organic cannabis growers. They are a great source for high quality soil inputs packaged for a garden (rather that legit field) scale. If you're friendly they usually have lots of samples of cool and expensive stuff also.

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