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.

Controlled Traffic Farming (CTF) is an imperative for the ultimate in soil health

A group of no-till farmers gather for a farm tour and begin talking about soil compaction. Several of the farmers are using CTF (Controlled Traffic) for a decade or more, and are completely certain that CTF is an imperative to produce deep loose soil with no compaction and deep aggregate structure.

The farmer hosting the get together says, “I am certain I don’t have compaction! Let me grab my shovel and let’s go out to the field. I’ll show you I don’t have compaction!”

One of the CTF farmers raises his hand and says, “Wait. You just said it. You said, “Let me grab my shovel.” If you need a shovel, you have compaction. On my soils that have been CTF for 20 years, you can go into the field with your bare hands, and the question is, How deep do you want to dig?”

2020-03-16T13:59:16-05:00February 5th, 2020|Tags: , |

To till or not to till

Is it more desirable to have your soil at a pH of zero or a pH of 14?

Is it more desirable to have water at 100% field capacity or at 0% field capacity?

Is it more desirable to till soils or no-till?

Each of these is a false dichotomy. Options exist on the spectrum, not only at the opposing polarities.

The dogmatic debate about tillage versus no-till needs to die. It serves no one and traps us in a false duality of thinking.

We need to change the conversation. Instead of ’tillage’, we might consider ‘soil particle management’.

The objectives of optimal soil management might be to improve:

  • surface protection
  • aggregate stability
  • water infiltration
  • water percolation
  • gas exchange
  • microbial community function and balance
  • redox poising/buffering
  • (what else would you add to this list?)

Any tool or cultural management practice that improves these objectives of soil health should be adopted. Those which do not, should not.

Which tools and management practices achieve the objectives?

2020-03-16T13:55:20-05:00January 16th, 2020|Tags: , |


Go to Top