Greetings of a Sunday all! I wanted to get back to the conversation we were having on organic vs. synthetic nutrients, and ions vs. ions.
Last week,
@The Celt posted a
response to my "ions are ions" link (and nicely did not generate a debate on which type of growing is better!). He did post a
link to newer research than my
article from 20 years ago. And Celt's link was an academic research paper that was pretty much beyond my understanding.
Still, I was trying to get my head around this weird coincidence in the different ways plants uptake nutes that allow us to feed them in an entirely different way from their evolutionary development, so I went back to try to read through that article. The first time I was overwhelmed while scrolling through it, and this time I thought I would start with the abstract:
"In this paper, we describe a mechanism for the transfer of nutrients from symbiotic microbes (bacteria and fungi) to host plant roots that we term the ‘rhizophagy cycle.’ In the rhizophagy cycle, microbes alternate between a root intracellular endophytic phase and a free-living soil phase. Microbes acquire soil nutrients in the free-living soil phase; nutrients are extracted through exposure to host-produced reactive oxygen in the intracellular endophytic phase. We conducted experiments on several seed-vectored microbes in several host species. We found that initially the symbiotic microbes grow on the rhizoplane in the exudate zone adjacent the root meristem. Microbes enter root tip meristem cells—locating within the periplasmic spaces between cell wall and plasma membrane. In the periplasmic spaces of root cells, microbes convert to wall-less protoplast forms. As root cells mature, microbes continue to be subjected to reactive oxygen (superoxide) produced by NADPH oxidases (NOX) on the root cell plasma membranes. Reactive oxygen degrades some of the intracellular microbes, also likely inducing electrolyte leakage from microbes—effectively extracting nutrients from microbes. Surviving bacteria in root epidermal cells trigger root hair elongation and as hairs elongate bacteria exit at the hair tips, reforming cell walls and cell shapes as microbes emerge into the rhizosphere where they may obtain additional nutrients. Precisely what nutrients are transferred through rhizophagy or how important this process is for nutrient acquisition is still unknown."
To me, that says that microbes absorb the nutrients in the soil. Those nutrients are released to the roots in response to specific chemical interactions that make the microbe's cell wall break down, allowing the roots to extract those nutrients. The microbe is then released back into the free-living soil and they obtain additional nutrients, beginning the cycle again. It also ends with:
"Precisely what nutrients are transferred through rhizophagy or how important this process is for nutrient acquisition is still unknown."
When I went searching for more information, I found a number of articles from respected universities that basically say "an ion is an ion."
[Note:
Bold mine in all quotes below.]
This one from Michigan State University (from the same year as Celt's article) states:
"The fundamental process of nutrient absorption by plants is well established. Irrespective of whether nutrients originate from organic or inorganic sources, plants are only capable of absorbing nutrients in certain forms. For example, nitrogen is only absorbed as nitrate (NO3-) ions or ammonium (NH4+) ions and potassium only as K+ ions. Thus, plants do not differentiate between nutrients derived from organic and inorganic fertilizer sources."
And here is
a Science Daily summary of the Rutgers University article Celt posted. It boils it down into five paragraphs, including this summary:
"The rhizophagy cycle works like this: Plants cultivate -- essentially farm -- microbes around root tips by secreting sugars, proteins and vitamins, according to White. The microbes grow and then enter root cells at the tips, where cells are dividing and lack hardened walls. The microbes lose their cell walls, become trapped in plant cells, and are hit with reactive oxygen (superoxide). The reactive oxygen breaks down some of the microbe cells, effectively extracting nutrients from them. Surviving microbes spur the formation of root hairs on roots. The microbes leave the hairs at the growing hair tip, where the hair cell wall is soft, and microbes reform their cell walls as they reenter soil. The microbes acquire nutrients in the soil and the process is repeated over and over, according to White, who has been studying the sustainable cycle for seven years."
What the Rutgers' research seems to have discovered is not that plants don't absorb ions in organic grows, but
the method by which they absorb them.
So after further reading, I'm going back to my original statement that plants cannot differentiate the source of the nutrient ion. Ions are involved whether the plant gets its nutrition from the microbes or directly from the soil.
I am not saying that there aren't other benefits to an organic grow as I have
mentioned, but it still looks like an ion is an ion.
Thanks to Celt for spurring me on to do further reading on this. Everything I take the time to understand makes me that much smarter!
I hope everyone's weekend was warm and sunny.
), I also received my MOTY prize from 
We're not sure which shot they're giving yet, so it's either one-and-done or one-and-come-back-in-a-few-weeks! The instructions say it could be any of the three available.
