AM Fungi and Phosphorus

[rrog]

I had previously assumed that the "food" for the fungus or bacteria was simply dead root cells. And this may still be the case. What is fascinating is that the plant roots provide Hexose (a sugar that Bacillus would love) to feed and signal the Fungus that more connections are needed.

After establishment, the fungus provides much more surface area than the original root hairs.

Some amazing things...

 

[*Journeyman*]

I know dextrose is used on large scale biological based farms specifically to stimulate Bacillus activity.

As for the whole phosphate thing Tennessee Brown is the most readily avilaible. Soft rock is not very solubale but do know the micronized version works better. One farm consultant I talked to turned me on to Tennessee Brown and said far superioir to soft rock. Even Idaho phosphate is better than soft rock and some say soft rock can contain more contaminants because of how it is obtained. TB is 23% P2O5 with an immediate availability up to 0-12-0.

Here's one link:
http://www.cropservicesintl.com/CutNChemical.htm

Here's a link that seems to contradict what I said lol:
http://soil.scijournals.org/cgi/content/abstract/21/2/183

I've heard that any material coming out of Florida is highly contaminated.

 

[MrFista]

Fungi make exudates for solubilizing rock, including rock phosphate. My copy of mycelium running is on loan, but there's an electron micrograph image in it of a fungal species producing crystals for rock 'breaking.'

Fungi also have bacterial associates. With mycorrhiza (which is not a fungi, it is a term representing the relationship between fungi and plant) there are MHB's - mycorrhizal helper bacteria. Some fungi have been associated with bacillus sp. Much more to be learned yet.

 

[rrog]

MrFista, ni pic, but would love to see it.

MHB? That's actually what they're called? Man! This is really something. Really. Thanks so much for these tidbits!

 

[MrFista]

You're welcome rrog. I love this subject but am only a learner. I get to hang out with clever phuks though and you bet I ask a lot of questions. I'm also lucky in that I don't have to pay for databases as I'm at school.

A typical soil contains far more phosphate that a plant requires. It's some ridiculously high amount, that is already there, but yes, it's insoluble. "Organically unavailable"...

Then fungi get hold of it, and other species, as we're learning, and make it available.The addition of phosphate, imo, is a waste of money unless you know you are growing short season and mycorrhizae are not present or at least were not encouraged. Then by all means as small a particulate size as you can organically get - phuk it - sometimes we just want results.

Adding P early to a soil full of microbes is the second best way, imo, to deliver P.

And now we know, put some lacto b in there. To make Lacto b? It's spelt out beautifully in Jaykush's Lacto Bacillus thread - on this website, in this organic section.

The best way is as nature intended, mycorrhizal partnership, and the other critters too, lactos eating galactose glucose and who knows, it gets complex... All part of a big picture, a circle, that recycles.

But I just must try and add shit to nature and make it better. Is this 'human nature'. I know it's a hella lot of fun trying to understand all of this stuff, but a big job I'll likely never finish...


I sure love learning and pretending at understanding some of it. It's just awesome down under the dirt.

 

[rrog]

A typical soil contains far more phosphate that a plant requires. It's some ridiculously high amount, that is already there, but yes, it's insoluble. "Organically unavailable"...

Then fungi get hold of it, and other species, as we're learning, and make it available.The addition of phosphate, imo, is a waste of money unless you know you are growing short season and mycorrhizae are not present or at least were not encouraged.

That's pretty much where I'm at. I wasn't aware that a good soil was often sufficient with P already. There are plenty of studies showing AM Fungi squeezing P out of very poor, Phosphorus depleted soils.

I also like the thought that established AM Fungi provide much more surface area for absorption than the plant root hairs alone. That's a striking realization.

I think the biggest point isn't that Fungi are a waste because we add P and kill it. The biggest point is that the AM Fungi doesn't need the added P, and it's the added P that's the real waste.

Thanks for the dialog everyone. Very interesting.

 

[jaykush]

That's pretty much where I'm at. I wasn't aware that a good soil was often sufficient with P already. There are plenty of studies showing AM Fungi squeezing P out of very poor, Phosphorus depleted soils.

i want to point out that is if your using real soil in your mix, peat based mixes will need the P added in low amounts

 

[quadracer]

Found some interesting and relevant links.

http://www.rodaleinstitute.org/20040401/Hamilton

http://newfarm.rodaleinstitute.org/depts/NFfield_trials/0903/factsheet_mycorrhiza.shtml

AM fungi are affected by a number of standard agricultural practices. Here are the negatives and positives of a few common practices from the soil biology point of view:

1. Fertilization- Years of P fertilization can lead to very high soil P levels. Plants that are able to absorb sufficient P via their roots alone in high nutrient soils inhibit the spread of colonization by the fungus. This reduces the flow of sugars to the fungus which lessens the amount of the fungus in the soil. Low or no P fertilization is necessary in such soils.
2. Winter Fallow- Another practice that negatively impacts AM fungi is over winter bare fallow. This removes potential host roots from which the fungi can receive sugar during mild fall and spring weather, thereby decreasing viability and the ability of the fungi to colonize the next crop. An over winter cover crop may not only be useful for nutrient management, but can serve as another host plant for the mycorrhizal fungi and will boost the amount of AM fungi in the soil.
3. Crop Rotation- Continuous monocultures have been shown to select for less beneficial AM fungi. The reason for this is that the AM fungus species that proliferate with a particular crop may not be the best ones for stimulating the growth of that crop. These mycorrhizal fungi may even contribute to the yield decline seen in continuous monoculture. Therefore, it is best to grow a variety of crops in rotation. Further, some plants do not become colonized by AM fungi and therefore will depress populations of these fungi. Among these crop plants are members of the mustard family (rapeseed, cabbage, cauliflower, etc.), spinach, and lupine.
4. Weed Control- Weeds can act as kind of an instantaneous crop rotation. Since the diversity of the AM fungus community can be proportional to the associated plant community, strict and complete weed control decreases the diversity and efficacy of the indigenous community of AM fungi. The best thing, from the soil biology perspective, is to manage weed pressure to keep it just below levels that would impact yields.
5. Tillage- The mycorrhizal fungus hyphae in the soil act both as the nutrient absorbing organ of the mycorrhiza and as the way in which new roots are colonized. Tillage disrupts both of these functions. On the other hand, seedlings grown in no-tilled soils become colonized by AM fungi more rapidly and have greater phosphorus status than those grown in tilled soils.

 

[rrog]

JayK: I guess that would hold true for anything less that 100% soil, right? Like a coco based medium as well as peat?

Quad, as usual, great stuff. Thanks for the continued contributions.

 

[jaykush]

JayK: I guess that would hold true for anything less that 100% soil, right? Like a coco based medium as well as peat?

yes, coco is just coco. and it can only contain whatever nutrients coco is made of( which i dont know)

but then even when using soil, it depends on the soil your using. for example a clay soil is most likely going to have more P than a very sandy soil. just because of things like to leech out of sandy soils and not so much in clay soils. so its best as always to know your sources and materials. it makes you life and the micro organisms lifes much easier.

 

[Dignan]

This is a great thread here. Thanks to all of you.

One side-point I'd like to point out here is that gardeners who don't grow organically or who don't care to grow fully organically will tend to read threads like this and decide that organics "is so hard."

Understanding organics and plant/soil biology is hard; but then again, having a true understanding of what is happening when you grow in non-living soil is also quite difficult.

Growing plants in living, organic soil is actually very simple, and it's more about what you don't need to do than what you need to do.

Case in point here: you don't need to add much, if any, P to your soil... if your soil is truly alive and thriving.

Carry on.

 

[rrog]

Good points Dignan. We're actually simplifying things.

 

[*Journeyman*]

Here's an OK article by Lawerence Mayhew about phosphorous and it really turned me off at the end because he was kind of promoting a product. So I called him to talk about the whole thing . Nice guy and explained things a bit better.

For some reason the link is a bit messed up so you need to Google "rethinking phosphate sources mayhew" and it's the first hit. While looking for the paper I found this about rock phosphate sources running out but in like 30 years:

http://sei-international.org/index.php/news-and-media/1618-the-looming-crisis-for-phosphate-rock

 

[*Journeyman*]

Case in point here: you don't need to add much, if any, P to your soil... if your soil is truly alive and thriving.

There's something like when you add highly soluble P to soil it quickly gets bound up as phosphates anyway and becomes unavailable and ultimately it falls back on the shoulders of the fungi to make that bound up P available again. I'm pretty sure that's pretty close as I can't seem to put my finger on those notes.

 

[rrog]

You're the #1 link on Google at the moment!

Am reading and digging his paper. Will report back.

 

[rrog]

I see the comment you're referring to.

"Actually, the plants utilize a small percentage of the total soluble fertilizer applied. In the case of phosphorous, the application of soluble P creates a shift in the chemical equilibrium with about 1/3rd of the fertilizer locking up with positively charged metal ions in the soil. About 1/3rd runs off as a water pollutant and rest of it becomes available to the plant, ironically, by microbial activity. As the combination of harsh chemicals actually reduces soil humus and harms microbes, the process becomes self-defeating."

Not thinking that all grows have enough positive metal ions to lock up much Phosphorus. Coco would unless Ca+ is around, as Ca+ is a more powerful Cation. Not sure what I said means beans.

What a great rundown of the history of farming and fertilization. And once again giant companies are sticking it up our collective ass.

 

[*Journeyman*]

You're the #1 link on Google at the moment!

LOL...I always wanted to be #1! That's what I needed to plug in to find the link to his paper. For sure if you come across anything Lawrence has written it should be some pretty solid stuff . His paper on humates simply rocks and THE best single comprehensive writeup on humates I've seen yet.

 

[*Journeyman*]

and rest of it becomes available to the plant, ironically, by microbial activity.

Heh heh...there it is. You can try and circumvent natural activity but ultimately you can't

 

[*Journeyman*]

Not thinking that all grows have enough positive metal ions to lock up much Phosphorus. Coco would unless Ca+ is around, as Ca+ is a more powerful Cation. Not sure what I said means beans.

Well...there's a way you can mix cations and anions in the same solution without them canceling each other out, basically, but that's for another day. Don't know if that really applies here but it's late...lol.

 

[MrFista]

Very Interesting Journeyman. Any greenies want to make a name and fortune for themselves get cracking on solutions for recycling phosphorus.

It's mainly Al and CU that P binds to in soils. You could use these elements to remove P from waste streams. But how do you reuse it once it's recovered...