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Which does the most damage, tillage, herbicide, or fertilizer?

When growers discuss the damage to soil biology from herbicide applications, and possible alternatives, one of the first questions/justifications is: “Doesn’t tillage harm the soil more than herbicide applications?” Michael McNeill believes applied products often have a bigger negative contribution than tillage.

From the Regenerative Agriculture Podcast with Michael McNeill:

John: You’ve iterated several times that you have to stop doing what inflicted the damage in the first place. What I heard you saying was that it’s really the herbicides and fungicides and the insecticide applications that are causing this degradation of soil health. And I heard you mentioned that these herbicides and these various pesticides that people are applying are actually chelation agents.

Why do you believe that these products are the causal agent for the suppression of soil health? Couldn’t it also be the extensive tillage that we had for a number of decades and some of these other contributing factors?

Michael: Well, I have some farms that I feel are way over-tilled. They’re organic farmers. They really do till excessively, in my mind. But it doesn’t seem to be bothering the soil at all. It isn’t quite as good as I’d like to see it, but as long as they’re keeping their organic matter up, preventing erosion, using cover crops, and that sort of thing, the tillage in itself doesn’t seem to be doing as much damage as I originally thought it would.

Now, having said that, you have to be careful which tillage tools you use. A disc is not a very good tillage tool to be using—it causes compaction, it fractures the soil structure much worse than a tined implement that you could pull through—whether that be a v-ripper or a narrow-pointed field cultivator. These kinds of things do not seem to do the structural damage that I see with things like the disc, or even like a moldboard plow or a field cultivator with sweeps on it.

John: In essence, you’re saying that tillage doesn’t have the damaging effects on soil health that the herbicides do, from your perspective.

Michael: It’s not as bad as the herbicides, not as bad as anhydrous ammonia, and not as bad as the high-salt fertilizers. They tend to be more of an issue. And when you put them all together, it overwhelms the soil-life system.

John: I understand the impact of anhydrous ammonia and salt fertilizers—both of those are very oxidizing and can have the potential to produce a lot of damage to the soil’s microbial community. But I don’t understand how herbicides would have that same effect. You mentioned herbicides being chelating agents. From your perspective, how is it that herbicides and these various pesticides have such a damaging effect on soil health?

Michael: We have not paid a lot of attention to micronutrients in the soil. Micronutrients are extremely important to plant growth. And they are readily and easily chelated by the pesticides that we use. And once you tie them up, you start shutting down significant pathways. That’s where my physiology training and background came into play—when I started seeing a lot of these physiological processes being shut down.

An example people are probably familiar with is that if you chelate manganese and tie it up, you shut down the shikimate pathway. When you shut that down, diseases can move in very quickly, because that’s sort of the plant’s immune system, if you will. If you shut that down, you have to buy fungicides. You put on the fungicides to protect your plant from the disease that’s invaded, and then you start killing more of the fungal life in the soil. And it’s a vicious, vicious cycle that you’ve set up.

When to use inoculants to regenerate soil

In our experience, when microbial inoculants are applied as part of a different nutrition management system, they have consistently been some of the most significant ROI applications, and produce dramatic changes in soil health. Yet, many growers buy ‘bugs in a jug’ and see little or no response. When this happens, it often because the applied inoculant was put into the wrong environment, was not supported with biostimulants, or fertilizer and pesticide applications were continued. Don’t expect to continue managing everything else the same, and a microbial inoculant will change soil biology. The biology became degraded in the first place because of management practices and product applications. If these remain the same, don’t expect biology to make a miraculous comeback.

From the Regenerative Agriculture Podcast with Michael McNeill:

John: When you have a degraded system like that—where there are suppressed yields and suppressed soil health, as you’re describing it—how do you go from depressed yields of 70 to 90 bushels per acre back up to 200, with aspirations of going back up to 250 bushels per acre? How do you achieve that?

Michael: Well, it’s a long, hard task. There aren’t any silver bullets. You have to figure out what was going wrong and stop doing that—that’s number one. Number two, you’re going to have to look at what it’s going to take to remediate the soil. Has the soil become really hard—hard like a road? I get penetrometer readings where it takes 500 pounds of downward pressure to penetrate the top two inches of the soil—that’s hard. That’s just like a gravel road. A crop will not grow in that.

When they tilling it, it’s breaking up into chunks. And then when it rains, it puddles and it just seals over. And so we get no oxygen into the soil. You have to incorporate some tillage, and then you have to start providing some food for the microbial life—which is almost non-existent. It’s not non-existent, because you can bring it back—that’s the good news. If you don’t let this thing go too long, you can bring it back.

Now whether we’re bringing all of it back or not, I don’t know. But once you get it started coming back, then you can look at inoculating with mycorrhizae and some of the things—the pseudomonads, the actinomycetes—that could be missing, and stimulate them. But first, you have to get oxygen into the soil, get the water working correctly, and get the food right. There’s no magic in inoculating the soil—if it’s loaded with poison, it will kill your inoculant. You have to fix that problem first before you try inoculating. You wouldn’t have to do an inoculation, but it does speed it up—you gain about a year, maybe two years, when you do that.

I see people thinking they’re buying a magic silver bullet by inoculating, but then they continue to do the things that caused their soil to die in the first place. And they’re not winning. They’re losing.

Pesticides as a cause of soil degradation

Many agronomists and farmers with three or four decades of experience describe how soil health deteriorated quickly when herbicide and pesticide use became mainstream. Michael McNeill shares his observations.

From the Regenerative Agriculture Podcast with Michael McNeill:

John: And when you say you have about 165,000 acres that you work on today, what is the scope of the work you do on each of these farms?

Michael: Most of it is working with soil health and soil fertility, and helping growers select the right genetics for the fertility programs that they’re working with. Soil health is becoming a bigger and bigger issue for me to deal with. When I first started, it wasn’t a really big issue. It’s huge now. And so I’m devoting more of my time now to soil health than I ever thought I would.

John: I’d love to talk about that a little bit—when you say that soil health didn’t used to be a big issue, and now you’re spending a lot of time on it, what changed with soil health? How are you managing it differently today than you were twenty or thirty years ago?

Michael: Well, it’s interesting that you would ask me that, John. The other day I was cleaning out a drawer in my desk, and I found some old pictures that I had taken back in 1972 or 1973 of crops that were growing. I had some close-ups and some overviews of the field. The thing that I noticed was how healthy the plants were. There were no disease lesions on them anywhere. The corn plants were just perfect. And the whole field was that way.

It’s really hard to find a field today that is that way. I was looking at the weeds that were growing along the fence rows, and they were big and healthy and looked great. They don’t look so good today, comparatively speaking. And you say, “Well, maybe that’s a good thing!” No, it’s not. The whole area that we’re farming is unhealthy. It makes me ask the question—what’s changed?

To me, the big difference from that era until today is that farmers have been drawn into big ag. You need to use herbicides. You don’t want to use a cultivator. You have to farm more land. So you use herbicides, but herbicides are doing things to the soil, because they’re all chelators. So now the plants become a little bit imbalanced in the nutrition that they’re taking up, and you find more disease—you find more insect pressure. So you start using fungicides and insecticides—more chelators, more poisons being dumped onto the ground. And you’re pretty impressed with how they work. The field is perfectly clean, and weed free—excellent. The diseases were dramatically reduced. The fungicides worked really well. The corn borers and some other of the insects that were issues went away. It was magic. The chemistry was totally magic—it looked beautiful.

But as time went on, the chemistry started poisoning the good things that were in the soil. And so, today, I’m called out to look at farms where the guy’s production has dropped off dramatically and the soil is virtually dead.

John: When you say the production has dropped off dramatically, what have you observed?

Michael: Looking at ten-year crop insurance records, the guy was getting 190 to 210 bushels per acre and had around a 200-bushel 10-year average. Excellent, excellent yields. Now it’s getting 70- and 80-bushel yields. That’s dramatic, and it will put him out of business very quickly.

John: That is very dramatic.

Michael: This isn’t just happening on a little field here, a farm there. I’m seeing 8,000- and 10,000-acre farms that this has happened to. And that really, really woke me up. I started seeing this about five years ago. I’ve been working with these growers who are asking me whether I can help them remediate that. Can I help bring the farm back? And in a three- to four-year period, we’ve had pretty good success. I would say we’re back now at where we were when this crashed.

The farmers are excited that they can now take it to a different level—to the 250-bushel range or greater. And they can see growth and potential and doing what they’re doing. They’ve moved away from GMO crops, and they’ve particularly moved away from glyphosate.

Mining the sky, not the soil

Plants are mining the sky, not the soil. Plants are greater than 90% carbon, hydrogen, oxygen and nitrogen, all contributed from the air and water, not the soil.

Here is an excerpt from Charles Walters:

Jan Baptista van Helmont, a 17th century Flemish physician, started getting a handle on exactly what happens when he performed his now famous tree experiment. He simply wanted to know how soil matter was being displaced when plant life grew. No one could measure such a proposition in a field, or in a forest. So van Helmont planted a willow tree in a large earthen tub. The little sprig weighed in at 5 pounds. Soil used in the experiment scaled in at an even 200 pounds. The tub was then covered so that only a small hole for the tree trunk and one for watering remained.

Five years later the tree was not only larger, it now weighed 164 pounds. Obviously, reasoned van Helmont, if the willow tree picked up the difference between 5 pounds and 164 pounds, then the soil remaining in the tub should weigh only 41 pounds, potting material having been reduced to oven dry soil for the post growth weighin. The results proved van Helmont hopelessly wrong. After contributing to the tree’s growth for five years, the 200 pounds of soil had lost only 2 ounces. Van Helmont pondered the problem in deep consternation. Could it be that all this growth came from the water he had given the tubbed tree all these years? Surely this was the answer.1

We have learned a lot in the decades since this experiment. 

And we have also forgotten. 

The soil lost only 2 ounces out of 200 pounds, while the plant gained 164 pounds. 

At the end of the growing period, how much of the 200 pounds of soil do you suppose was organic matter? How much might there have been at the beginning?

Of the 164 pounds of plant biomass, how much do you suppose was mineral content? How much had the plant extracted that was no longer present?

We know that well-managed crops contribute more organic material to the soil than they remove, even when 100% of the above-ground biomass is removed from the field. Healthy soil and crop systems are always gaining carbon, and building organic matter. Mismanaged crops deplete soil organic matter. 

What remains to be better defined is the mineral contribution. Experiential evidence suggests that when crops are healthy, the level of soil available minerals constantly increases as well, tapping into the soil mineral matrix of reserves. How many centuries can that be maintained, and what depth of soil profile should we calculate to answer that question? 

  1. Walters, C. Eco-farm: An Acres USA Primer. (Acres USA, 2003).

 

2020-03-16T13:39:03-05:00December 17th, 2019|Tags: , , |
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