I shared this presentation with my Soil Fertility class last week (last week of August 2011). It is an updated version of earlier presentations that I have shared on roots.

1. ROOTS
The hidden half of agriculture

2. Bill Darrington (Persia, IA)
Reading
for this week

3. Read the attached article and submit answers using WO before the start of class
this Friday (8/2).
1) Describe several factors contributing to deep root growth on Bill Darrington's
farm.
2) The article refers to Ray Rawson as the guru of "vertical farming"... what is
"vertical farming“ and what did Bill Darrington learn from Ray Rawson about soil
aeration?
3) Why does Bill Darrington dig so many soil pits and what does he look for?
4) What is Bill Darrington's perspective on anhydrous ammonia? Do you agree
with this perspective?
5) If you had a chance to meet Mr. Darrington, what would you want to ask him?
6) Have you ever looked at roots in a soil pit? If so, describe something you
observed. If not, when do you think you will have an opportunity to look at some
roots? What do you think you will see?

5. Getting dirty with 2 champions of Vertical Farming
Francis Childs
Ray Rawson
VF = Management system for optimum
root extension and function

6. Tillage systems
affect root
extension and
function
Adapted from Hunt et al. (1986)

7. Shallow high-speed vertical tillage tools can be part of a
vertical farming system
shallow high-speed vertical tillage tools = VF
http://www.farm-equipment.com/pages/Vertical-Tillage-Product-Showcase.php

8. main purpose = sizing residue
http://media.yetterco.com/726JDVTA.jpg

9. High-speed vertical tillage tools preserve root channels!
1 pass with high-speed vertical tillage tools leaves most of the
previous year’s corn roots intact, anchored and still in place.
Regardless of soil type, 22,000 – 25,000 corn root systems
per acre were observed in place.
http://www.soils.wisc.edu/extension/wcmc/2011/ppt/Klingberg.pdf

10. Disk ripping in late fall
at the Allison Farm
14”

11. “Horizontal tillage, works soil uniformly in a horizontal
plane. Years ago, horizontal tillage meant moldboard
plowing. Today, it typically involves running a field
cultivator, disk or soil finisher 3" or 4" deep in the spring
before planting. Following soybeans, it often means
doing no tillage in the fall and making one pass with a
soil finisher before planting corn in the spring. It's a
reliable way to get fast emergence and uniform stands”.
"The downside of horizontal tillage is that it creates
an abrupt change in soil density between the worked
soil and the layer at the bottom of the implement's
working depth."
Comments by Ken Ferrie in Farm Journal - September 1, 2006

12. “Whether a density change becomes a problem depends on
the year. Heavy rains early in the season may pond on the
sudden density change leading to nitrogen loss and plant
health problems - If it's hot and dry in July and August and
the first three sets of crown roots turn on the sudden density
layer, you won't have the root depth to get through a
drought.“
"One of our primary goals is to get the first three sets of
crown roots deep into the soil… In vertical-tillage, no-till
or strip-till conditions, the first set of crown roots will go
down. But, when we do horizontal tillage before planting-
except in a few conditions like sand-no matter what we did
in the fall, the first two sets of crown roots almost always
turn on the dense layer. Hopefully, with fall vertical tillage,
the third set will penetrate.“
Comments by Ken Ferrie in Farm Journal - September 1, 2006

13. Long term no-till
(w/ healthy soil biology)
Intensive tillage
Network
Plow pan of cracks
and
biopores
Ontario Ministry of Ag and Food

14. When do roots pull out of
Ken Ferrie inspecting corn roots on the Noland Farm in Blue Mound, IL
the ground like this?

15. Biodrilling ???
Annual
ryegrass
roots
penetrating 40”

16. Another type
of biodrill

17. Visual evidence of biodrilling
Canola root
Rapeseed root

18. So…which approach
would you use ?

19. Proof that you are using the
right system
John McGillicuddy
IA crop scout

20. extensive
white color growth into
Healthy
shoot growth the sub-soil
proliferate and high minimal
in all yields evidence of
directions deformities
Efficient
use of soil
resources

21. Understanding corn root
development
The seed roots stop
growing shortly after
the coleoptile
emerges from the
soil surface.
The nodal root system becomes visible at ~ V1.
The nodal root system becomes the dominant
system by V6.

24. 4 weeks Corn root development
documented in the 1920s
8 weeks
16 weeks
If this was possible 90 years ago, just
think what is possible today?
7 feet deep !!

25. 1926
http://www.soilandhealth.org/01aglibrary/010139fieldcroproots/010139toc.html

27. All you need to do to grow healthy roots
is use rootworm resistant genetics… right??
When rootworm pressure is high, rootworm resistant
genetics normally result in much healthier roots

28. Rootworm resistant genetics are not a silver bullet !
Severe damage by corn
rootworm larvae to roots of
a biotech corn rootworm
hybrid
http://www.ipm.iastate.edu/ipm/icm/2006/11-13/btcorn.html

29. We have witnessed historically low densities of European
corn borers across Illinois and some nearby states that are
now believed to be linked to the widespread adoption of Bt
corn hybrids. Will we see a similar phenomenon unfold
with western corn rootworms? I suspect we might be
headed down this road. Will western corn rootworms adapt
as they have repeatedly done so in the past? If we don't
integrate management tactics, we could have the answer
sooner than we would like.

31. A team of ISU entomologists led by Dr. Aaron Gassman has
found evidence of root worm resistance to the Cry3Bb1
strain of protein toxin from Bacillus thuringiensis found in
Monsanto Bt corn varieties.
"We report that fields identified by farmers as having severe
rootworm feeding injury to Bt maize contained populations of
western corn rootworm that displayed significantly higher
survival on Cry3Bb1 maize in laboratory bioassays than did
western corn rootworm from fields not associated with such
feeding injury," the researchers said in an article published
on July 29 in the scientific journal PLoS ONE.

33. A significant correlation was found between the number
of years Cry3Bb1 corn had been grown in a field and
survival of western corn rootworm on Cry3Bb1 corn.
Interviews with farmers indicated Cry3Bb1 corn had been
grown for at least three consecutive years in all of the
fields containing resistant corn borers.
The researchers concluded insufficient planting of
refuges and non-recessive inheritance of resistance may
have contributed to resistance.
They noted a 2009 study done by the Center for Science
in the Public Interest indicated only 50% of Bt maize
planted in Midwest complied with EPA requirements for
refuge size and proximity to Bt fields.
http://cornandsoybeandigest.com/blog/bt-resistant-corn-borers-spur-concerns

35. “Most important, though, for effective corn rootworm
management is to consider a long-term, integrated
approach that includes multiple tactics, such as adult
suppression programs, use of soil insecticides at
planting, rotation of Bt hybrids that express different Cry
proteins, and rotation to nonhost crops. Many producers
have relied on a single tactic for too many years, and
unfortunate consequences are beginning to emerge.
As harvest gets under way this fall, I suspect that more
producers in northwestern Illinois will encounter lodged
corn that has been severely damaged by western corn
rootworms. As I learn more about this evolving situation,
I will keep you informed”.
Mike Gray – U of I Extension Entomologist

36. What do you know about corn rootworm biology ??
Western corn rootworm beetle Northern corn rootworm beetle
Diabrotica virgifera Diabrotica barberi

37. http://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList

38. http://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList

39. http://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList

40. Goose
necking
http://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList

41. http://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList

42. http://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList

43. http://plantandsoil.unl.edu/croptechnology2005/plant_phys/?what=animationList

44. In North and South America, corn rootworms are attacked by
many pathogens, predators and parasitoids, some of which
are specialized natural enemies of corn rootworms.
European entomologists are studying natural predators of corn
rootworms (collected from soils in N. and S. America) for use in
controlling corn rootworms in Europe (where rootworms are not native)

45. Studies have shown that
many of the natural enemies
of CRW are more common in
reduced-tillage systems, and
in fields with higher levels of
organic matter.

46. Journal of Economic Entomology
Article: pp. 330-339 | Abstract | PDF (1.44M)
Disruption of Host Location of Western Corn Rootworm Larvae with
Carbon Dioxide
E. J. Bernklau, E. A. Fromm, and L. B. Bjostad
Department of Bioagricultural Sciences and Pest Management, Colorado
State University, Fort Collins, CO 80523
Elevated concentrations of carbon dioxide (CO2) prevented western corn
rootworms from locating the roots of growing corn in behavioral bioassays
conducted in soil tubs. When CO2 was pumped into one end of a soil tub,
significantly more larvae were recovered from soil at the treated end than
from soil around a growing corn plant at the opposite end of the tub. In
controls with ambient air pumped into one end of a soil tub, significantly
more larvae were recovered from the soil around the corn plant than from
soil on the treated side. Larvae were unable to locate the roots of corn
seedlings when CO2-generating materials were mixed into the soil.

47. When damaged by corn rootworms, the roots of
some corn plants release a chemical called (E)-β-
caryophyllene that recruits an entomopathogenic
nematode (Heterorhabditis megidis) to feed on
corn rootworms.
Corn breeding has resulted in loss of the (E)-β-caryophyllene signal in
some varieties, drastically reducing their ability to recruit H. megidis.
Under field conditions, the infection rate of corn rootworms with H.
megidis were found to be 5x higher on a corn variety producing the
below-ground signal than on a variety that does not. Moreover, spiking
the root system of a non-producing variety with synthetic (E)-β-
caryophyllene decreased the emergence of corn rootworm adults
by > 50%.

49. Nematode diversity
Bacterivore Fungivore
Plant parasitic Predatory

50. competition parasitism
Soil biology can both promote and
inhibit crop root growth and
function
antibiosis induced resistance

51. The growth promoting effects of soil
biology are underappreciated

52. Dramatic effect of steam
sterilization and compost on
growth of pepper plants

53. This unfortunately
is the norm in
agriculture
Acute
root
VS.
disease
Chronic root
malfunction

54. Chemical toxicities
can inhibit root growth
Aluminum
toxicity
Aluminum
toxicity
Al toxicity is very common in
the SE US and in tropical
countries like Brazil

55. Understanding aluminum toxicity
Fe and Mn toxicities also
occur at lower pHs
Toxic forms
of Al are
bioavailable
at pHs < 5.5
Aluminum toxicity
is minimal above
a water pH of 5.5
http://www2.ctahr.hawaii.edu/tpss/research_extension/rxsoil/alroot.gif

57. What damaged these corn roots?
B was included in
starter fertilizer

58. In-row fertilizer can damage crop roots
http://www.sdstate.edu/ps/soil-lab/loader.cfm?csModule=security/getfile&PageID=788496

59. Why do crops on tiled-drained land tend to
be more drought resistant ?
Do crop roots grow toward water?
Roots elongate in aerobic soil!
Ontario Ministry of Ag and Food

60. Sub-soil water
and nutrients
Brady and Weil (2002)

61. Waiting for drier soil
Sidewall compaction
is the most important strategy

62. You really won’t know what is happening
underground unless you take a look…

63. All you need
is a shop-vac
and a hose!
Its just like going to the dentist!

64. Roots have many functions !

65. In addition to the most obvious functions
physical support and uptake of water and nutrients
ROOTS are:
Carbon pumps that feed soil organisms and
contribute to soil organic matter
Storage organs
Chemical factories that change soil pH,
poison competitors, filter out toxins,
concentrate rare elements, etc.
A sensor network that helps regulate plant
growth

66. Macro-
anatomy of roots

67. Micro-anatomy of roots
http://www.sparknotes.com/biology/plants/plantstructures/section2.rhtml

68. Physical protection
source of lubrication,
& sensor of gravity
What is the function
of the root cap?

69. The cell wall of the endodermis (pink inner strip of cells) is waterproofed by the
Casparian strip, which forces water to enter the symplast before it can enter the
root xylem
phloem
root hair
xylem
epidermis
endodermis
cortex

70. Apoplast vs. symplast
The movement of fluids from the root hairs to the xylem
can occur through one of two conductive pathways– the
apoplast and the symplast.
The apoplast route consists of inter-cellular spaces
within the root cortex along which water and solutes can
diffuse.
The symplast route consists of channels through cells
along which water and solutes are actively transported.

71. http://www.mie.utoronto.ca/labs/lcdlab/biopic/fig/35.03.jpg

72. Nutrient uptake can be an active or a passive process
outside cell
inside cell
Plants are highly selective for potassium!!

73. Outside cell
Inside cell

74. K+
H+
- The pH of a plant’s
NO3 rhizosphere changes as
the plant regulates its
H+ internal charge balance.

75. Which plant received nitrate (NO3-)?
Which plant received ammonium (NH4+)?
http://departments.agri.huji.ac.il/plantscience/topics_irrigation/uzifert/4thmeet.htm

76. The ins and outs of plant nutrition
H20
Root exudates
N, S, P activate soil microbes Transpirational
stream
H 20
Diffusion
Root growth
Microorganisms produce
most but not all of the
enzymes need to digest OM

77. Plants take up mostly inorganic forms of nutrients
when inorganic forms of nutrients are readily available
In some natural ecosystems (e.g., tundra), organic
forms of nutrients are very important

78. Why does
water move
up into
plants?
Water moves upward
through plants
whenever there is a
negative gradient of
water potential along
the soil-plant-
atmosphere
continuum

79. H20
A continuous Solar energy
chain of water
drives the
molecules is process
pulled up
through the Plants provide
plant the conduit
H20
H20
H20

80. Rhizosphere
Roots normally
occupy < 1% of topsoil
volume
The rhizosphere is
normally << 10 % of Zone of root
topsoil volume influence

81. Navigating the rhizosphere
End of the
Rhizoplane rhizosphere
Endo-
Rhizosphere Ecto-Rhizosphere
Microbial activity
> 90%
< 10% of soil
volume
of soil
volume
A few millimeters
(Lavelle and Spain, 2001)

82. Healthy
cowpea
nodule
with a
pink
interior

83. Legume
nodules
come in
many shapes
and sizes

84. Lots of complicated biochemistry – very intensively studied!!
Legume
love
affair
Sarrantonio

85. Examples of rhizobia innoculant

86. Inoculation groups for commonly grown legumes
Alfalfa Group Alfalfa
(Rhizobium meliloti) Black medic
Bur clover
Button clover
White sweetclover
Yellow sweetclover
Clover Group Alsike clover
(Rhizobium trifolii) Arrowleaf clover*
Ball clover
Berseem clover
Crimson clover
Hop clover
Persian clover
Red clover
Rose clover*
Subterranean clover*
White clover
Cowpea Group Alyceclover
Soybean has its own inoculation group!!
(Bradyrhizobium japonicum spp.) Cowpea
Kudzu
Peanut

87. How much N do soybeans fix and how much
of this N is left behind after harvest?
N
-N
A good soybean crop will fix >150 lbs of N/ac but
>200 lbs of N may be removed in the harvested beans.

88. Historically crop rotations
revolved around LEGUMES

89. Mycorrhizae - internet of the soil

90. 2 main types of mycorrhizal associations
Ectomycorrhizae
AM endomycorrhizae
Arbutoid
mycorrhizae
Ericoid
endomycorrhizae
Orchid endomycorrhizae
Lavelle and Spain (2001)

91. Mycorrhizal Networks: Connecting
plants intra- and interspecifically
•Many plants are
connected
underground by
mycorrhizal hyphal
interconnections.
•Mycorrhizal (AM)
fungi are not host
specific.
Illustration by Mark Brundrett

92. Increase nutrient (P) uptake suppress pathogens
Mediate plant competition Improve soil structure
Glomalin
Superglue
of the soil ??

93. There are many
mycorrhizal
inoculants on the
market and some
evidence that they
work but it is
important to keep in
mind that they are a
much less proven
technology than
legume inoculants

94. There are lots of examples of dramatic
responses to mycorrhizal inoculation in
reforestation projects

95. Is this really possible?
Tree roots often extend >2 times farther than the canopy

96. ?