I pulled a moringa seedling out of a flat this spring to look at how the roots were coming along. The white stretch behind the tip had a film on it that came off on my fingers. That film is a good part of the reason the seedling was growing at all, and for a long time I had no idea what it was doing down there.

What goes on in that spot has a name. Researchers call it the rhizophagy cycle, and James White's lab at Rutgers did most of the work that put a name to it. Rhizophagy means root eating, which sounds backwards until you find out which direction the eating runs.

The Short Version

Bacteria living loose in the soil get pulled into the root at the growing tip. The plant takes a share of them apart for what they are carrying. What survives gets pushed back out through the root hairs, goes back to living in the soil, picks up more, and comes back around. A root is not a straw sitting in a nutrient solution. It is closer to a barn.

What Happens Inside the Root

The bacteria start on the outside, on the root surface just behind the growing point. From there they work in between the cell wall and the membrane underneath it. Once they are in that space they shed their own walls and go soft.

Then the plant does something I did not see coming the first time I read about it. An enzyme sitting on the root cell membrane pushes out superoxide, a reactive form of oxygen. It breaks down a portion of the bacteria parked in there, and the nitrogen and minerals they were carrying come loose inside the root cell where the plant can take them up.

The bacteria are not just standing there for it. They put out nitric oxide, which meets the superoxide, and the two of them make nitrate. Nitrate is a form roots take up readily. So the chemistry the bacteria use to keep from being broken down ends up feeding the plant anyway. The ones that come through it get moved along to the root hairs and pushed back out into the soil, walls and all.

Then they do it again. A root tip pushing through soil is running this cycle the whole way down.

Why It Changed How I Think About the Ground

I was taught, the way most of us were, that you feed a plant. You read the numbers on a bag, you put the numbers on the ground, the plant takes them up. That picture is not wrong so much as it skips a step, and the step it skips is alive.

If a good share of what a plant eats comes in riding inside a bacterium, then the population of bacteria in the ground is not a side matter. It is the delivery. Thin that population out and the plant is left with whatever it can pull from solution on its own, which is less than it wants and less than it could have had.

That is the reason we do not put synthetic chemicals on this ground. Not as a slogan. The cycle above only runs if there are living microbes in the soil to run it, and the fastest way to end up with fewer of them is to keep hitting the ground with things that kill them.

What It Looks Like Here

• We keep something growing on the ground most of the year. Bare dirt in an Alabama August gets hot enough to be a poor place to live.
• Compost and leaf mulch go on in the fall, and we let the worms take it down rather than turning it in.
• Tillage stays light. Every pass with steel breaks up fungal threads that took a season to run.
• When a moringa row comes back after a hard pollarding, that is not the tree working alone. There is a whole population underneath it moving nitrogen up.

None of that is complicated and none of it is new. What was new to me was the mechanism, and knowing the mechanism made me a good deal more careful about what I put on the ground.

Questions I Get

Is rhizophagy the same thing as mycorrhizal fungi?

No, though they overlap and both show up in the same soil. Mycorrhizal fungi run threads out past the root and hand nutrients back at the root surface. Rhizophagy brings the microbes all the way inside the root cell. Fungi can go through the cycle too, not only bacteria.

Do I need to buy an inoculant?

Most ground already has what it needs, and the money is usually better spent on cover and compost than on a jug. If you are starting on ground that has been farmed hard for years, an inoculant can give you a head start, but it will not hold if there is nothing there to feed it.

How would I know if it is working?

Dig up a seedling and look at the root behind the tip. You want to see fine root hairs and something clinging to the surface rather than a clean white root in loose dry dirt. Earthworms in the top few inches are the other tell, and they cost nothing to count.

Does this work the same in a pot?

It can, if the potting mix has life in it. A sterile mix with a fertilizer schedule is running the plant on solution alone. That is why a plant in the ground so often outruns the same plant in a container even when the container gets fed more.

Where to Read More

If you want the field version rather than the paper version, I wrote about why moringa comes back so fast after we cut it, and about how we pollard the trees. The soil under those rows is doing a lot of that work.

The moringa leaf powder we sell is grown in that ground, picked, dried and ground here in Opp. And if you are working on your own place and want to talk it through, we do farm and homestead consultations.

Greg