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Regenerative Agriculture Podcast

Apr 28, 2018

In this episode, I had the pleasure of interviewing Dr. Don Huber, a leading plant pathologist and Professor Emeritus at Purdue University. We discuss how to manage soil-borne diseases by managing crop rotations, and the management needed to grow 500 hundred bushels corn.

Don shared intriguing observations on how soil-borne disease pathogen populations remain present in the soil constantly and are actually ‘beneficial’ saprophytic fungi until the right environment is present. Root diseases are a result of the soil environment, not a result of the presence or absence of the organism.



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Episode 4 - Dun Huber - Highlights

2:40 - What are Don’s most memorable moments leading him to where he is?

  • Don has fun wherever he is!

3:10 - What has puzzled Don in his research work?

  • Studying soil ecology is looking at a black box. Need to slowly build a picture of everything involved.


4:10 - What is something that has surprised Don?

  • How seemingly contradictory things all work together, such as a lot of nutrient relationships
  • Secondary functions of things like manganese and iron start to come into play
  • What are the ecological niches that make the system work?


6:30 - Challenge of manganese availability. What is contributing to that?

  • It’s a dynamic relationship with soil and fungi.
  • Need organisms and nutrients to increase uptake
  • Need the bacteria that are responsible for the valiant state - oxidizing groups and reducing groups
  • Manganese can be there, but not available for uptake


11:10 - Pathogens dependant on manganese oxidation. Are they directly dependent, or are they producing a manganese-deficient plant? 

  • Both can be correct. They don’t necessarily need the oxidation.
  • Enzyme isn’t going to work for you without a cofactor



13:50 - How do populations change when you have a crop infection?

  • The plant is providing nutrients and resources for the pathogen
  • Soil inhabitant vs soil colonizer
  • A soil colonizer is an organism that can be provided its nutrient base from a host
  • Infection isn’t the result of the presence of the pathogen, but the level of plant health and microbial ecology in the rhizosphere


20:20 - What are the tools the growers have available to manage soil ecology most effectively and to develop a disease suppressant soil profile.

  • Crop rotation - each crop influences a certain group of organisms in the soil
  • Cover cropping
  • Time of tillage
  • Farming is really managing ecology


28:30 - Is it also possible to use these tools to manage and suppress soil-borne pathogens? 

  • Definitely!


31:20 - What are some useful crops or cover crops that have a strong disease suppressive effect?


  • Depends on disease and overall soil biology
  • Perhaps the best crop: Oats!


36:50 - What are the key characteristics shared by disease suppressing crops?

  • Boils down to nutrition - may be indirect or direct


39:10 - Can fall tillage application create a rebalancing effect of both reducing organisms as well as oxidizing organisms?.

  • Yes! Doesn’t have to be every year
  • Long term no-tillage can reduce the efficiency of ecology


41:20 - What are the impacts of nitrogen on developing disease suppressive soils?

  • Most soil organisms are hungry for 2 things: nitrogen and carbon
  • Changes can cause massive stimulation


44:30 - What is the impact of ammonium on an ecosystem with reduced nitrogen

  • Tremendous reduction of disease
  • Reducing environment creates an increase of manganese availability


46:30: What is the impact of carbon-nitrogen ratio on disease suppressive soils as well as yield?

  • Depends on the carbon source
  • It’s not the carbon to nitrogen ratio, it’s the form of nitrogen involved
  • Ratio works if working with the same nutrient source


48:30 - Quality/Quantity of photosynthesis - How can we increase quantity of photosynthesis and quantity of root exudates in soil profile.

  • Manganese, manganese, iron, sulfur, etc. are essential for photosynthesis
  • Mineral nutrient deficiency will reduce overall efficiency.


54:30 - We are not tapping into efficiency of plants by limiting carbon dioxide


55:10 - Increase in photosynthesis producing increased biomass


55:30 - What is the potential for plants to increase their volume of photosynthesis? 

  • The potential is 100%
  • 5-10x depending on what the plant it, starting point, etc.


1:00:30 - What kind of yields did Don achieve during his yield trials? What plant populations were growers using? 

  • 350+ bushel


1:07:10 - What happened from then, to today when growers are struggling to grow 250 bushel? Why were these not adopted on a broader scale?

  • Focus moved to other areas when there was “too much production”
  • Requires a long term commitment
  • Private company interest is the bottom line
  • We forget it’s an ecology that needs to be managed


1:11:30 - What is something Don believes to be true about modern agriculture that others do not believe to be true?

  • Have to think about entire systems, and not focus on a single piece
  • You have to make a few mistakes in order to get there


1:14:00 - What does Don see as the biggest opportunity in agriculture today? 

  • Reinventing the wheel!
  • Getting back to nutrient density
  • Eliminating pesticides, especially glyphosate
  • Agriculture is the basic infrastructure of society. Recognizing the stewardship we have to the soil


1:18:10 - What are some books or resources Don would recommend?


1:22:30 - What is a question Don wishes John had asked him?

  • Glyphosate’s impact on soil ecology
  • Don is excited to see cover crops being used
  • Maintaining balance within soil environment
  • Supporting the crop with nitrogen




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