Managing for Healthy Roots


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

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Managing for Healthy Roots

  1. Managing for Healthy Roots Dr. Joel Gruver School of AgricultureWestern Illinois University
  2. My first wading pool garden in July 2009The watermelon root system on the title slide was exhumed from this pool in September.
  3. Housing project garden in early June~ 1 month after transplanting
  4. Wading pools filled with compost are not an optimal rooting environment but arean example of the plasticity of plant root systems. With limited rooting volume but adequate water and nutrients, it is possible to grow abundant crops.
  5. How many of you regularly look at crop roots ? What do you look for?
  6. Evidence of healthy roots extend into the white color B horizon Healthy shoot growth and good minimalproliferate in all yields evidence of directions deformities Efficient use of soil resources
  7. Feed the soil vs. Feed the crop ?
  8. Both strategies are important ! Unhealthy roots use nutrients inefficiently… but healthy roots need available nutrients !Plants with poorly developed roots tend to havenutrient deficiencyand drought stress Acute root symptoms disease Chronic root malfunction
  9. Corn seed roots stop growing shortly after the coleoptile emerges from the soil surface. The nodal root systembecomes visible at ~ V1. The nodal root system becomes the dominant system by V6.
  10. 4 weeks 8 weeks 16 weeks 7 feet deep !!
  11. 1926
  12. I have not read this book but it looks interesting!
  13. Cotton plant Sub-soil water and nutrients Brady and Weil (2002) Brady and Weil (2002)
  14. You won’t know what is happeningunderground unless you take a look…
  15. All you need is a shop-vac and a hose!Its just like going to the dentist!
  16. Tillage systems affect root architecture Adapted from Hunt et al. (1986)
  17. Long term no-till (w/ healthy soil biology) Intensive tillage Network Plow pan of bioporesOntario Ministry of Ag and Food
  18. Which optionwould you use ?
  19. WIU Allison Organic Research Farm – September 2007
  20. Early MayWarmer and drier than soilwith other cover crops and almost no weed growth
  21. The experiment was planted to corn on May 29 2008 Corn following radishestablished well, had the lowest in-row weed pressure and yielded about 10 bu more than the no radish treatment.
  22. Visual evidence of biodrillingCanola rootRapeseed root
  23. Artificial drainage has greatly increased the number of days when soils are suitable for deep root growth but has also contributed Pollution of to manywater resources environmental Loss of SOM problems
  24. Chemical toxicitiescan inhibit root growth Aluminum toxicity Aluminum toxicity
  25. 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
  26. Galled root system of tomato infected with root-knotnematode, Meloidogyne sp., compared with non-infected root system Root pathogens can inhibit root growth
  27. Nematode diversity Bacterivore FungivorePlant parasitic Predatory
  28. Roots have many functions !
  29. Absorptive network for limiting soil resources ofwater and nutrientsMechanical structures that support plants,strengthen soil, construct channels, break rocks,etc.Hydraulic conduits that redistribute soil waterand nutrientsHabitats for mycorrhizal fungi, rhizosphere andrhizoplane organisms
  30. 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
  31. Protection and lubricationWhat is the function of the root cap?
  32. H20A continuous Solar energychain of water drives the molecules is process pulled up through the Plants provide plant the conduit H20 H20 H20
  33. Understanding the “ins and outs” of root function Root H 20 NO3-1 exudates Transpirationalactivate soil stream microbes Ca+2 H 20 Root growth Iess mobile nutrients like phosphorus
  34. How many of you regularly plant transplants that look like this?
  35. How many of you are familiar withthis system of growing transplants?
  36. My personal experience is that making and handling soil blocks can be a tedious process but the quality of the transplants is excellentLarge scale automated soil block production and planting is common in Europe
  37. 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
  38. Raised beds promote healthy roots !! Faster drainage and soil warming Greater depth of fertile soil Restricted traffic
  39. No wheeltraffic on beds
  40. Where is the party? Rhizoplane End of the rhizosphere Endo- Root free soil Rhizosphere Ecto-Rhizosphere > 90% of < 10% of soil soilBiological activity volume volume A few millimeters (Lavelle and Spain, 2001)
  41. Pink is good!N-fixing nodules on a cowpea plant
  42. Lots of complicated biochemistry – very intensively studied!!Legume love affair Sarrantonio
  43. Examples of rhizobia innoculant
  44. Inoculation groups for commonly grown legumesAlfalfa Group Alfalfa (Rhizobium meliloti) Black medic Bur clover Button clover White sweetclover Yellow sweetcloverClover Group Alsike clover (Rhizobium trifolii) Arrowleaf clover* Ball clover Berseem clover Crimson clover Hop clover Persian clover Red clover Rose clover* Subterranean clover* White cloverCowpea Group Alyceclover (Bradyrhizobium japonicum spp.) Cowpea Kudzu Peanut
  45. Conservation Augmentation3 broad goals of ecological Activation management
  46. Historically crop rotationsrevolved around LEGUMES
  47. 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
  48. 133 lbs of K/ac 52 lbs of Ca/ac Hairy Vetch 3,260 lbs of DM/ac 141 lbs of N/ac18 lbs of P/ac 18 lbs of Mg/ac
  49. Myco = fungus Mycorrhizal diversityRhiza = root Ectomycorrhizae Most woody plants AM endomycorrhizae Most herbaceous Arbutoid plants including mycorrhizae corn and soybeans Ericoid endomycorrhizae Orchid endomycorrhizae Lavelle and Spain (2001)
  50. Close up of an arbuscule(one way that mycorrhiza connect to the plumbing of plants)
  51. Increase nutrient uptake suppress pathogens (especially P) MycorrhizaeMediate plant competition Improve soil structure Glomalin Superglue of the soil ??
  52. 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
  53. This is just an example of a product not an endorsement!
  54. Trichoderma biofungicide product
  55. Mixed Results
  56. competition parasitism 4 modes of actionantibiosis induced resistance
  57. Radishes seeded with a push planter in late August 2008Bio-strip tillSeptember 2008
  58. September 2009 Attempt #2
  59. Tillage radish on 30” rows with oats on 7.5” rows November 2009
  60. Radish planted on 30” rows using milo plates in mid-August 2010
  61. It is normal for the fleshy root of cover crop radishes to rise3 or more inches out of the ground. This is not a sign of compaction!
  62. Large scale conventional grain producers are starting to experiment with bio-strip-till. Ontario, Canada
  63. Annual ryegrass w/crimson cloverAnnual 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