When micronutrient levels in tissue analysis don’t correlate with field observation

My frustration with tissue analysis a decade ago that lead to our use of sap analysis was that tissue analysis results did not correlate to disease and insect pressure, which the literature indicated should be possible. Tissue analysis also did not correlate with field observation of deficiency symptoms. Michael McNeill discusses how accumulated pesticides residues in the soil profile can chelate micronutrients, and continue to hold them in chelated form even after they have been absorbed by the plant. The chelation constants of many pesticides are much stronger than naturally occuring chelation agents like amino acids and organic acids.

From the Regenerative Agriculture Podcast with Michael McNeill:

John: Michael, what is something that you’ve puzzled over for a really long time? What’s really caught your attention in the agriculture space that you’ve been working on?

Michael: Well, something that I’ve finally figured out, I think, was the impact of the lack of availability of micronutrients in our crops. I was doing tissue testing, for example, and I had adequate copper and iron and manganese and magnesium and calcium—everything looked good. What I didn’t realize was that a lot of those minerals were chelated. They were tied up into a form that the plant could not use—yet they showed up on a chemistry test when we tested the tissue. And when I finally figured that out, then everything started to gel for me.

John: I think what you’re saying is that these various minerals and trace minerals were being chelated inside the plant tissue by the herbicides and fungicides that growers were applying.

Michael: Yes. When I tested the plant, it had adequate levels. But when I looked at the plant, it was showing deficiency symptoms. You could look at it and just tell that there was a zinc deficiency or a manganese deficiency; it was obvious. But when I tested it, it was fine. Why was that? And it’s when I learned about this chelation issue and how it can be such a problem.

John: This is something we’ve been monitoring for a number of years. And it seems that, in some cases, sap analysis reports those a bit more accurately. And perhaps that doesn’t take all the chelation into account—but of course it’s still extracting nutrients that are held within the plant sap, and it’s still possible for them to be chelated. We do see the sap analysis correlate more accurately to what the plants are actually showing visually.

Michael: I would agree. I think the sap analysis has been a good step forward. When I figured out this chelation effect, that’s when it really gelled for me and I could understand why I was seeing deficiency symptoms in what, on paper, looked to be an appropriately healthy plant.

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.

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