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Terminating cover crops with glyphosate

For those who are yet undecided,

Evidence continues to accumulate regarding the pronounced negative effect of glyphosate on soil health, and how it leads to disease enhancing soils.

A new paper recently published describes how using glyphosate to terminate an oats cover crop alters the soil microbial profile as compared to a cover crop that is mowed1.

The conclusion? Glyphosate alters the microbial community dynamics, some species become more dominant, while others are suppressed. Not a surprise. We know from prior work by Huber et. al. that glyphosate applications shift the microbial population in the direction of a disease enhancing environment.

A second recent publication describes how minerals are lost from cover crops sprayed with glyphosate and don’t seem to remain plant available in the soil profile.2

If you want to develop disease suppressive soil that prevents possible infections of soil-borne bacteria or fungi, there doesn’t seem to be a place for glyphosate in the toolbox.

1. Allegrini, M., Gomez, E. D. V., Smalla, K. & Zabaloy, M. C. Suppression treatment differentially influences the microbial community and the occurrence of broad host range plasmids in the rhizosphere of the model cover crop Avena sativa L. PLoS One 14, e0223600 (2019)..

2. da Costa, J. V. T. et al. DECOMPOSITION AND NUTRIENT RELEASE FROM CROTALARIA SPECTABILIS WITH GLYPHOSATE APPLICATION.

2020-03-16T13:49:21-05:00January 3rd, 2020|Tags: , , , |

Spring applied planter solution products influence end of season cover crops

This is a field in Pennsylvania in December 2019.

It appears the section on the left has less residue, and possibly more cover crop growth.

The only difference is that the planter solution used for planting the corn crop in the spring was a product blend (AEA) that enhanced biology (left), as compared to a ‘conventional’ ionic planter solution that suppresses soil biology (right).

2020-03-16T13:48:25-05:00January 2nd, 2020|Tags: , |

The bulls-eye of the wrong target

We have become masterful at hitting the bull’s eye of the wrong target.

A colleague sent me a recent article1 describing the discovery of a master gene that regulates iron absorption in plants. You can read a journalist’s popularized version here.

Just so we are clear, iron absorption is not a genetics problem. This is a soil redox and microbial problem.

There is abundant iron in the earth’s crust and in our soils, around 4% or so. Most soil analysis results report excessive iron.

The iron that is in our soils, and that is measured on our soil analysis is often not physiologically active in plants because it is in the oxidized form that is unavailable for absorption. 

It is largely in the oxidized form because of how our soils have been mismanaged. We have shifted the microbial population and the general soil environment in the direction of excessive oxidation, and inadequate reduction. 

It is the function of beneficial microbial populations in the soil to convert iron and other elements from the oxidized to the reduced form and improve their plant availability. This only happens when we have a soil environment that can support the right biology and allow this transition to occur. 

When you change soil biology and redox status, crops will have an abundant supply of iron. And manganese. And cobalt. And copper.

Changing plant genetics to improve absorption of the wrong form of an abundant mineral completely misses the obvious.

Kim, S. A., LaCroix, I. S., Gerber, S. A. & Guerinot, M. L. The iron deficiency response in Arabidopsis thaliana requires the phosphorylated transcription factor URI. Proc. Natl. Acad. Sci. U. S. A. 116, 24933–24942 (2019).

2020-03-16T13:48:05-05:00December 31st, 2019|Tags: , , |

Redox as a driver of soil/plant/microorganism systems

Contemporary mechanistic agriculture has been based largely on the development of genetics and chemistry. 

The regenerative agriculture systems emphasize the development of biology and biophysics.

All the evidence points to an emerging agricultural revolution that will supersede the so-called “green revolution”, and exceed it in terms of crop quality and yield and economic returns to the producer. 

Since I first started working in this space I have been fascinated by the volume and integrity of high-quality science in the biophysics space that has not been utilized by mainstream agriculture, yet holds so much promise. 

One such topic is the role of soil redox in developing disease suppressive soils and regulating nutrient availability. Redox has at least as big an impact on nutrient availability as pH does.

Here is an important and foundational review paper1 that will get you started on this important topic.  Look for a more on this in the coming months. 

  1. Husson, O. Redox potential (Eh) and pH as drivers of soil/plant/microorganism systems: a transdisciplinary overview pointing to integrative opportunities for agronomy. Plant Soil 362, 389–417 (2013).

 

2020-05-05T08:57:27-05:00December 30th, 2019|Tags: , , , , |

Bacterial resilience to antibiotics

Antibiotics were first discovered being produced by a soil-borne fungus. We have identified many different antibiotics that are made by plants and fungus, and even synthesized some on our own. Many of the anti-biotics we have developed are not necessarily labeled as such. Many herbicides and pesticides would be examples of an antimicrobial that is applied to agricultural soils. The case for glyphosate is now well established, and others are getting to be better known.

When we consider the widespread use of antibiotics on our soils and in livestock feed we might wonder about the implications for the microbial community in our soils. 

I found this excerpt from Stephen Harrod Buhner1 thought-provoking: 

Once a bacterium develops a method for countering an antibiotic, it systemically begins to pass the knowledge on to other bacteria – not just its offspring – at an extremely rapid rate. Under the pressure of antibiotics, bacteria are interacting with as many other forms and numbers of bacteria as they can. In fact, bacteria are communicating across bacterial species, genus, and family lines, something they were never known to do before the advent of commercial antibiotics. And the first thing they share? Well, it’s resistance information.

Bacteria can share resistance information directly, or simply extrude it from their cells, allowing it to be picked up but later by roving bacteria. They often experiment, combining resistance information from multiple sources in unique ways that increase resistance, generate new resistance pathways, or even stimulate resistance forms that are not yet necessary. Even bacteria in hibernating or moribund states will share whatever information on resistance they have with any bacteria that encounter them. When bacteria take up any encoded information on resistance they weave it into their own dna and this acquired resistance becomes a genetic trait that can be passed on to their descendants forever. As Gaian researchers Williams and Lenton comment…

Microbe transfer between local populations carries genetic information that changes species composition and thus alters the nature of each community’s interaction with its local environment2.

“The nature of each community’s interaction with its local environment” changes. One aspect of that:  as bacteria gain resistance they pass that knowledge on to all forms of bacteria they meet. They are not competing with each other for resources, as standard evolutionary theory predicted, but rather promiscuously cooperating in the sharing of survival information. “More surprisingly,” one research group commented,  “is the apparent movement of genes, such as tetQ and ermB between members of the normal microflora of humans and animals, populations of bacteria that differ in species composition.” Anaerobic and aerobic, gram-positive and gram-negative, spirochetes and plasmodial parasites, all are exchanging resistance information. Something that, prior to antibiotic usage, was never known to occur.

And, irritatingly, bacteria are generating resistance to antibiotics we haven’t even thought of yet. For example, after placing a single bacterial species in a nutrient solution containing sublethal doses of a newly-developed and rare antibiotic, researchers found that within a short period of time the bacteria developed resistance to that antibiotic and to twelve other antibiotics that they had never before encountered – some of which were structurally dissimilar to the first. Stuart Levy observes that “it’s almost as if bacteria strategically anticipate the confrontation of other drugs when they resist one.”4

 

With the growing understanding of how we have compromised our soil biology, we need to consider how we can regenerate that microbiome, add the organisms that have been lost, and recover those that are present but struggling. This is where microbial inoculants, diverse plant species, compost, and compost teas become important tools in agriculture management systems.

 

  1. Buhner, S. H. Plant Intelligence and the Imaginal Realm: Beyond the Doors of Perception into the Dreaming of Earth. (Simon and Schuster, 2014).
  2. Williams, H. & Lenton, T. Microbial Gaia: A new model for the evolution of environmental regulation. Gaia Circular, 2007 14–18 (2007).
  3. Wax, R. G., Lewis, K., Salyers, A. A. & Taber, H. Bacterial resistance to antimicrobials. (CRC press, 2007).
  4. Levy, S. B. The Antibiotic Paradox: How Miracle Drugs Are Destroying the Miracle. (Springer, 2013).

 

2020-03-16T13:45:20-05:00December 16th, 2019|Tags: , , , , |

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