I shared this presentation on 1/22 at the SSAWG conference in Chattanooga, TN.

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

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

8. Housing project garden
in early June
~ 1 month after transplanting

9. 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.

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

11. Evidence of healthy roots
extend into the
white color B horizon
Healthy shoot
growth and good minimal
proliferate in all
yields evidence of
directions
deformities
Efficient use of
soil resources

12. Feed the soil vs. Feed the crop ?

13. Both strategies are important !
Unhealthy roots use nutrients inefficiently…
but healthy roots need available nutrients !
Plants with poorly
developed roots
tend to have
nutrient deficiency
and drought stress Acute root
symptoms disease
Chronic root
malfunction

14. Corn 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.

15. 4 weeks
8 weeks
16 weeks
7 feet deep !!

16. 1926

18. I have not read this book
but it looks interesting!

19. Cotton plant
Sub-soil water
and nutrients
Brady and Weil (2002)
Brady and Weil (2002)

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

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

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

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

24. Which option
would you use ?

25. WIU Allison Organic Research Farm – September 2007

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

27. 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 than
the no radish treatment.

28. Visual evidence of biodrilling
Canola root
Rapeseed root

29. Artificial drainage has greatly increased the number of
days when soils are suitable for deep root growth
but has also
contributed
Pollution of to many
water resources environmental Loss of SOM
problems

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

31. 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

33. 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

34. Nematode diversity
Bacterivore Fungivore
Plant parasitic Predatory

35. Roots have many functions !

36. 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

37. 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

38. Protection and lubrication
What is the function
of the root cap?

39. 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

40. Understanding the “ins and outs”
of root function
Root
H 20 NO3-1
exudates Transpirational
activate soil stream
microbes Ca+2
H 20
Root growth
Iess mobile nutrients
like phosphorus

41. How many of you regularly plant transplants that look like this?

42. How many of you are familiar with
this system of growing transplants?

43. My personal experience is that making
and handling soil blocks can be a
tedious process but the quality of the
transplants is excellent
Large scale automated soil block production and planting
is common in Europe

46. Most important characteristic of potting media
High moisture retention and rapid drainage
It can be difficult to optimize both
moisture retention and drainage in
real soils

47. Raised beds promote healthy roots !!
Faster drainage and soil warming
Greater depth of fertile soil
Restricted traffic

48. No wheel
traffic on
beds

49. Where is the party?
Rhizoplane End of the rhizosphere
Endo- Root free soil
Rhizosphere Ecto-Rhizosphere
> 90% of
< 10% of soil soil
Biological activity
volume
volume
A few millimeters
(Lavelle and Spain, 2001)

50. Pink is good!
N-fixing nodules on a cowpea
plant

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

52. Examples of rhizobia innoculant

53. 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

54. Conservation Augmentation
3 broad goals of
ecological Activation
management

55. Historically crop rotations
revolved around LEGUMES

56. Inoculation of cover crops is low cost way to increase N fixation
Typical amounts of nitrogen
fixed by legumes (lbs/ac/yr)
Alfalfa 150-300+
Soybeans Net loss 150-250
Red clover 75-200
Hairy vetch 75-200
Other annual forage
50-150
legumes

57. 133 lbs of K/ac 52 lbs of Ca/ac
Hairy Vetch
3,260 lbs of DM/ac
141 lbs of N/ac
18 lbs of P/ac 18 lbs of Mg/ac

58. Myco = fungus Mycorrhizal diversity
Rhiza = root
Ectomycorrhizae
Most woody plants
AM endomycorrhizae
Most herbaceous
Arbutoid plants including
mycorrhizae corn and soybeans
Ericoid
endomycorrhizae
Orchid endomycorrhizae
Lavelle and Spain (2001)

59. Close up of an arbuscule
(one way that mycorrhiza connect to the plumbing of plants)

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

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

62. This is just an example of a product not an endorsement!

63. Trichoderma biofungicide product

64. Mixed Results

65. competition parasitism
4 modes of action
antibiosis induced resistance

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

67. September 2009 Attempt #2

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

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

70. 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!

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

72. 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