I shared this updated version of a class lecture on roots with a group of seed company reps on 2/9/2011

1. Managing for
Healthy Roots
Joel Gruver
School of Agriculture
Western Illinois University
j-gruver@wiu.edu
http://www.slideshare.net/jbgruver/

2. The Furrow
ROOTS
The hidden half of agriculture

3. Bill Darrington (Persia, IA)
Interesting example of a farmer with a
root-focused management program.

4. How many of you regularly
look at crop roots ?
What do you look for?

5. Evidence of healthy roots
extensive
white color growth into the
sub-soil
Healthy shoot
growth and good minimal
proliferate in all
yields evidence of
directions
deformities
Efficient use of
soil resources

6. 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.

9. 1926

10. 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 !!

12. Corn College TV Episode 8 - Wednesday, Oct 20 2010
This episode digs deep with crown root development

13. Dig up a root ball

14. Dig up a root ball
Remove brace roots

15. Dig up a root ball
Remove brace roots
Inspect crown roots

16. Evaluating
corn rootworm
damage
http://www.fontanelle.com/util/resources/news/real-word-agronomy

17. 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

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

19. We have witnessed the 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.

20. U of I Corn Borer survey results

21. Sidewall compaction
?

22. Is this the solution?
Waiting for drier soil
is the most important strategy

23. Sometimes it is valuable
to dig a soil pit.
John McGillicuddy
IA crop scout
A pit will allow you to look deeper and see
how the soil volume is being explored

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

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

26. Tillage systems
affect root
architecture
Adapted from Hunt et al. (1986)

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

28. Ken Ferrie’s perspective
As the root moves through the soil it tapers
down, but when it hits a sudden density
change, ‘it’s like a fly hit the screen. It’s too Vertical
tight and it twists, bends and runs tillage tool
horizontally," said Ferrie.
"What causes the sudden density change? Ken Ferrie – Farm Journal
Compaction. If it hits a compacted layer, it turns
and runs on top of it."
Ferrie added the drastic change is caused by a
farm in horizontal tillage. "You can’t use horizontal
tillage without putting in a horizontal layer"
Horizontal tillage creates loose soil on top and a
firm shelf underneath, and the density change
creates difficulties for roots which are trying to
penetrate the firmer layer.

29. Cotton plant’s perspective
Sub-soil water
and nutrients
Brady and Weil (2002)

30. My first wading pool
garden in July 2009
The watermelon root system on the title slide was exhumed from this pool in Septembe

31. Watermelon root system exhumed from a wading pool

32. Wading pools filled with compost are *not* an optimal rooting environment but
are an example of the plasticity of plant root systems. With limited rooting
volume but adequate water and nutrients, it is possible to grow abundant crops.

33. Does this look familiar?
Compaction Saturated soil is
probably extends less compressible
several feet deep than wet soil

34. Which solution
would you use ?

35. Prevention through improved drainage maybe the most effective strategy
Artificial drainage has greatly increased the
number of days when soils are suitable for deep
root growth
but has also
contributed
to many
Pollution of environmental
water resources problems Loss of SOM

36. WIU Allison Organic Research Farm – September 2007

37. January

38. February

39. Early May
Warmer and drier than soil
with other cover crops and
almost no weed growth

40. Visual evidence of biodrilling
Canola root
Rapeseed root

41. The experiment was planted
to corn on May 29 2008
Corn following radish
established well, had the lowest
in-row weed pressure and
yielded about 10 bu more.
Mechanism(s) of
yield enhancement??

42. Chemical toxicities
can inhibit root growth
Aluminum
toxicity
Aluminum
toxicity

43. 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

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

46. http://www.sdstate.edu/ps/soil-lab/loader.cfm?csModule=security/getfile&PageID=788496

47. Galled root system of tomato infected with root-knot
nematode, Meloidogyne sp., compared with non-
infected root system
Root pathogens can
inhibit root growth
http://www.agnr.umd.edu/users/nrsl/entm/nematology/images/eis143.jpg

48. Root knot juvenile penetrating a tomato root

50. Both strategies are important !
Feed the soil vs. Feed the crop???
Unhealthy roots use nutrients inefficiently…
Healthy roots need available nutrients !
Healthy roots grow
in soils with a
favorable balance Acute
of air, water and root
soil organic matter
disease
Chronic root
malfunction

51. Roots have many functions !

52. Absorptive network for limiting soil resources
of water and nutrients
Mechanical structures that support plants,
strengthen soil, construct channels, break
rocks, etc.
Hydraulic conduits that redistribute soil water
and nutrients
Habitats for mycorrhizal fungi, rhizosphere
and rhizoplane organisms

53. Carbon pumps that feed soil organisms and
contribute to soil organic matter
Storage organs
Chemical factories that may change soil pH,
poison competitors, filter out toxins,
concentrate rare elements, etc.
A sensor network that helps regulate plant
growth

54. 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

55. Understanding nutrient uptake
H20
Root exudates
N, S, P activate soil microbes Transpirational
stream
H 20
Diffusion
Root growth

56. Nutrient uptake is an active and selective process
outside cell
inside cell

57. Rhizosphere
Roots normally
occupy < 1% of topsoil
volume
The rhizophere is
normally < 10 % of soil
volume Zone of root
influence

58. 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)

59. Healthy
cowpea
nodule
with a
pink
interior

60. Legume
nodules
come in
many shapes
and sizes

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

62. Examples of rhizobia innoculant

63. 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
(Bradyrhizobium japonicum spp.) Cowpea
Kudzu
Peanut

64. Mycorrhizal associations
Ectomycorrhizae
AM endomycorrhizae
Arbutoid
mycorrhizae
Ericoid
endomycorrhizae
Orchid endomycorrhizae
Lavelle and Spain (2001)

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

66. Trichoderma biofungicide product

67. competition parasitism
4 modes of action
antibiosis induced resistance

68. Like many emerging
technologies with real potential
- field results have been
inconsistent

69. Radishes seeded with a push
planter in late August 2008
Bio-strip till
September 2008

70. September 2009 Attempt #2

71. Tillage radish on 30” rows with oats on 7.5” rows
November 2009

72. Radish planted on 30” rows using milo plates
in mid-August 2010

73. It is normal for the fleshy root of cover crop radishes to rise
3 or more inches out of the ground. This is not a sign of compaction!

74. Large scale conventional grain producers
are starting to experiment with bio-strip-till.
Ontario, Canada

75. Annual ryegrass
w/crimson clover
Annual ryegrass is a very deep rooted cover crop that has good
tolerance of wet soils, combines well with other species and
produces less above ground biomass than cereal rye