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.
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 !!
11.
12. Corn College TV Episode 8 - Wednesday, Oct 20 2010
This episode digs deep with crown root development
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.
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.
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
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
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??
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
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
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
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)
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 ??
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