May 18, 2018
This week, I had the pleasure of
interviewing Dr. Larry
Phelan, a professor at Ohio State University where he heads
research programs studying the role of soil communities in plant
health and susceptibility to disease and insect pests in biological
farming systems. Larry also heads programs researching the
identification and behaviors of plant secondary compounds and
insect pheromones that affect host finding and other
behaviors.
In this episode, Larry and I
discuss plant and insect communications, soil communities, and the
concept of biological buffering - the capacity of biology in the
soil to absorb large amounts of nutrients that are applied and
contain those in their cells and release them over a period of
time. We also talk about Larry’s new initiatives in the city of
Cleveland to incorporate urban agricultural systems. I had a lot of
fun with this episode - some of the topics Larry touches on are
absolutely fascinating.
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Episode 8 - Larry Phelan - Highlights
3:10 - What are the memorable
moments leading up to where Larry is today?
- Larry
was trained as a chemical ecologist - where he would identify
pheromones and plant attractants
- As he
started talking to organic farmers, he noticed they had fewer
issues with insect pests than conventional farmer
neighbors
5:30 - What were the differences
that Larry noticed in organic farming?
- During
this time, many organic farmers were doing their own
research
- Many
organic farmers had animals integrated into their farms
- “If we
have healthy soil, then we are going to have a healthy plant, and
insects don’t like healthy plants” - Larry was seeing the truth to
this and wanted to test
- Larry
wanted to figure out if insects could tell a difference between
plants from organic farms, and if this was more related to the
short-term effects of fertilizer or the long-term effects of
mismanaged soil
- The
results: Regardless of fertilizer used, the plants growing in soil
from the organic farm received few insects eggs
9:20 - Biological
Buffering
- With an
influx of organic matter, you create a soil community that is
beneficial to the plant
- Nutrients absorbed into the soil community are
released over time - putting the plants in better nutrient
balance
- Plants
are almost always limited by nitrogen levels - they’re going to
take all they can get and will take more than they can deal
with
- Insects
are also limited by nitrogen, so plants with excess nitrogen are
very nutritious for insects
- No
difference in production between organic and conventional
farms
15:20 - Why can insects not
utilize plants as a food source that doesn’t contain as many amino
acids
- Free
amino acids can short circuit the plant defense system - Insects
get these free amino acids they don’t have to break
down
- Proteins vary in digestibility in
insects
18:20 - What had surprised during
Larry’s research into all of this?
- 30%
ammonia and 70% nitrate resulted in best plant growth
- Where
the plant was out of balance, that’s where the insects grew the
largest and had the best survivorship
- Survivorship of insects dropped as they
approached the 30/70 ammonia/nitrate ratio
22:40 - What is some practical
advice growers can implement?
- The
importance of organic matter added to the soil to sustain a
beneficial microbial community
- Important to distinguish between old organic
matter and biologically active organic matter - need to focus on
active organic matter
26:10 - What is the impact of a
nitrogen application on soil biological profile?
- Plants
can shut out mycorrhizae and can grow a shallow root
system
- When
the plant invests in growth above ground, it doesn’t have as
effective of a root system to gather water and
nutrients
- We
don’t want plants to encounter any extremes
- Starter
fertilizer isn’t allowing plants to grow resilience they need and
can cause plant growth to stall out
35:00 - Applying only insoluble
start applications
- Resulting in large root systems
- High
phosphorus levels without phosphorus application
- Mineral
profiles not very different in organic plants regardless of
fertilizer application
38:10 - What is something that
Larry believes to be true about modern agriculture that is
different from mainstream views?
- The use
of soluble fertilizers has been one of the most disruptive
practices in mainstream farming
- How
different organic farms view what they do - Conventional farmers
have a prescriptive approach. Organic farmers had more of a system
perspective
- “Tied
up” nitrogen isn’t a bad thing - It gives you “money in the bank”
in your soil
41:30 - What is a resource Larry
would recommend?
43:10 - What is a question Larry
wishes he was asked?
- Soils
in urban centers under vacant lots opening the possibility of urban
farming
- Do what
degree has the legacy of smokestacks, heavy metals, etc affected
soil community. Can these soils be rejuvenated or are these soils
effectively lost?
- The
influx of organic matter are reducing levels of lead and the
bioavailability of the lead - allowing cities to reduce the danger
of lead in soil
- Lead is
going to be there - need to find a way to bring it out
49:20 - Damaging impacts of
chronic pesticide use and exposure
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