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: , , , , |

Foliar feeding of plant nutrients

I have long been an advocate of foliar feeding nutrients as one of the most financially rewarding applications that can be made to a crop, and the practice has become mainstream in many regions. 

Thus, it comes as a surprise that in some areas growers still consider foliars to be an ineffective tool. I would suggest they are ineffective only when they are not properly designed and applied. 

Some of the first published papers on foliar feeding I have read were based on research conducted for the Atomic Energy Commission by Sylvan H Wittwer and Harold B Tukey in the late ‘40s and ‘50s. Their congressional testimony is as relevant and exciting today as when it was first published. (Approximately 1952?)

I cleaned up the document and made some slight edits to make it more readable, but kept all the underlining in the original report. You can read the 24 page report (and bibliography) here. You will find valuable and intriguing information. Here are some excerpts:

  • not only can plants absorb nutrients through the roots, but also through the foliage, the fruit, the twigs, the trunk, and even the flowers.
  • the most exciting news is the foliage feeding of plant—that plants can take up nutrients through the foliage. Here is a case where the farmer has really gotten ahead of the scientist as so often happens. He has learned that foliage feeding is helpful and he has adopted the practice. 
  • The first point I should like to make is that the materials do enter the leaves rather easily.
  • In the final analysis, we find that a leaf is a very efficient organ of absorption. We find that the materials move into the upper surface of the leaf as well as the lower surface. We find that it enters at night and during the daytime. Further, we find the leaf surface of a 12-year-old apple tree in Washington State to be equivalent to one-tenth of an acre, even though that tree only occupies about one-hundredth of an acre. So there is a large feeding area.
  • Not only do these materials enter rather easily—and this is interesting, too, because all the textbooks used to tell how the plant was covered by an impervious cuticle—now we find textbooks are re-written and the leaf is reported as a beautiful mechanism for absorption. 
  • If we apply it to the leaf we find it moves downward through the plant—at the rate of a foot an hour. It is very interesting that it moves so freely. If we apply it to a middle leaf it moves both ways very effectively.
  • We have seen that materials are absorbed by the plant and move rather freely in the plant. The amounts may at first seem relatively small, but to off set this handicap, the efficiency is high. In fact, this is the most efficient method of applying fertilizer to plants that we have yet discovered. If we apply these materials to the leaves in soluble forms, as much as 95 percent of what is applied may be used by the plant. If we apply a similar amount to the soil, we find about 10 percent of it to be used. 
  • For example, the soil may be cool and low in phosphorus at just the time it is needed by a transparent vegetable or strawberry plant. Or there are cases where the soil locks up certain materials that are applied, like potash and magnesium. Under such conditions we find leaf application very significant and very effective.
  • But now we are highly suspicious that here may be a case where materials are actually being leached out of the leaves maybe by overhead irrigation, maybe by rain, and having a profound effect upon the crop.  


2020-03-16T13:44:48-05:00December 20th, 2019|Tags: , , |

How to Propagate Aphids

It is important to propagate aphids in our fields so the beneficial insects such as lady beetles have something to feed on. It is quite easy to produce a tremendous aphid population which can sustain a large number of beneficials and not be negatively impacted. We just need to give them the right environment.

Here are the easy steps to produce an optimal environment for aphids, which require free nitrates in the plant sap.

Step one, apply more nitrogen then the plants can utilize at the current growth stage.

Step two, do not supply magnesium for better photosynthesis.

Step three, do not apply sulfur the plants needs to produce sulfur-bearing amino acids and complete proteins.

Step four, do not supply molybdenum for the nitrate reductase enzyme.

Step five, do not apply any boron that might boost plant immunity.

If you follow these five very simple steps, you can be sure that your crop will provide the perfect food source for aphids. In addition, it will also be the optimal food source for many other larval insects such as corn rootworm, earworm, corn borer, cabbage looper, tomato hornworm, and others. Really for any larvae. Propagating these larvae provides a ready food source for songbirds and beneficial insects, a valuable ecosystem service.

Of course, if you do not desire to propagate these insects on your crops, the solution is obvious. Do the reverse of the five easy steps, and these insects will not be able to use your plants as a food source.

What are the goals of organic and regenerative agriculture?

What are the objectives of regenerative agriculture ecosystems?

I can think of several possibilities:

  1. Produce enough exceptional quality, nutrient-dense, biofortified ‘food as medicine’ to influence public health and feed the global population a healthy diet.
  2. Produce pesticide-free food.
  3. Incentivize and proliferate small scale growers to develop local and regional food production.
  4. Develop agricultural systems that regenerate soil and ecosystem health and have them become adopted globally.
  5. Develop agricultural models that rapidly sequester carbon dioxide down to levels under 350 ppm.
  6. Reverse desertification, restore hydrological cycles and cool the climate.

Let’s be clear that these are different goals. Each is realistic and achievable. It is possible to achieve all of them together, but achieving one does not necessarily mean we achieve the others.

2020-03-16T13:45:40-05:00December 14th, 2019|Tags: , , |

Are diseases present because pesticides were not applied in time?

Do people or animals get bacterial infections because they have an antibiotic deficiency?

Do plants get disease infections because of a pesticide deficiency? If not, why do we apply pesticides before the organism is even present?

Come to think of it, plants do absorb antibiotics synthesized by soil microbes, and they help prevent possible infections. Maybe plants do become infected because of antibiotic deficiencies after all?

In that case, what produces the antibiotic deficiency?

That would be dysfunctional soil biology. Which is likely dysfunctional because of all the pesticide applications the soil has been exposed to.

Perhaps killing the microbes that protect our crops isn’t such a good management strategy.

2020-03-16T13:46:02-05:00December 10th, 2019|Tags: , , |

Insect susceptibility determined by types of plant sugars

Sugar metabolism and carbohydrate synthesis are at the very foundation of plant health, but we generally don’t learn much about them in agronomy or even entomology. The types of sugars and the relative concentration of different sugars contained within the plant seem to be foundational in determining susceptibility/resistance to many herbivorous insects.

Here are a few excerpts from Harold Willis1 I found interesting:

The role of sugar in insect attack of plants is fascinating. Based on research done on various insect and plant species, apparently insects like moderate amounts of plant sugars and are attracted to plants containing them. But high concentrations of sugars are avoided by leafhoppers, grasshoppers, and the European corn borer2

Alfalfa was found to be resistant to pea aphid when its stem tissues had a more acid ph and higher levels of sugar (pentoses) and pectic substances (larger carbohydrate molecules formed by linked sugars). Pentose sugars are formed from hexose sugars which are the original products of photosynthesis. Alfalfa plants that are normally susceptible to aphids will become resistant if the above-mentioned cellular changes occur3

A possible reason that some insects avoid high sugar plants comes from research by G Fraenkel. Some sugars and sugar alcohol combinations (glucoside and mannoside) interfere with normal utilization of other sugars, and so are toxic to insects (mealworms)4. The inhibitory sugars are found mainly combined with other molecules in plants, but if digested by insects and in the presence of the sugar glucose, their toxic effects occur5.

Our knowledge of plant immunology has progressed well beyond this research in the ’40s and ’50s, but the practical application has fallen well short. I describe how we have applied these principles in our plant health pyramid infographic and on YouTube here.

1. Willis, H. Crop pests and fertilizers – is there a connection?

2. Thorsteinson, A. J. Host Selection in Phytophagous Insects. Annu. Rev. Entomol. 5, 193–218 (1960).

3. Emery, W. T. Temporary Immunity in Alfalfa Ordinarily Susceptible to Attack by the Pea Aphid. Journal of Agricultural Research 73, 33–43 (1946).

4. Fraenkel, G. Inhibitory effects of sugars on the growth of the mealworm, Tenebrio molitor L. J. Cell. Comp. Physiol. 45, 393–408 (1955).

5. Dethier, V. G. & Rhoades, M. V. Sugar preference-aversion functions for the blowfly. J. Exp. Zool. 126, 177–203 (1954).

2020-05-22T07:17:19-05:00December 7th, 2019|Tags: , , , |

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