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20. Roots in the Soil - Angela Straathof

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How root trait diversity impacts the soil ecology and influences nutrient dynamics for the crop.

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20. Roots in the Soil - Angela Straathof

  1. 1. Root traits impact soil ecology and crop nutrient dynamics EOCC February 13 2018 Angela Straathof Post-doctoral Research Associate Soil and Ecosystem Ecology Group, University of Manchester @angiestraathof
  2. 2. So you’re here to learn all about roots… What are we talking about when we talk about traits? 1) Definitions and methods 2) Root exudates 3) Root traits and soil processes 4) Soil ecology and microorganisms 5) What are the unknowns? 6) What are the opportunities? 7) Future decision-making tools for Eastern Ontario
  3. 3. So you’re here to learn all about roots… Disclaimer: 1) Most of my examples are from ecology – this area of study is still emerging in crops 2) I don’t speak in t/ha 3) This information is conceptual! I’m here to get you thinking about the future
  4. 4. What are root traits? Characteristics Properties Belowground Difficult to measure! Increasingly used to predict productivity, and linked to above- ground traits
  5. 5. A) Architectural - How do the roots take up space? - Rooting depth - Root length density - Plant-specific and influenced by neighbours, resources, and soil type
  6. 6. Traits of an individual root B) Root diameter - Can vary within one plant - Determines nutrient transport capacity C) Tissue density - Also linked to water content, nutrient transport ability, consistent across plant
  7. 7. Traits of an individual root critical for crop performance D) Root physiology Nutrient uptake Root respiration - crops breathe belowground too! Root exudation Root exudates are critical for feeding the crop‘s belowground microbial army!
  8. 8. Traits of an individual root critical for plant performance E) Mycrorrhizal fungi - Crop P uptake - Plant receives P, fungi receives carbon: symbiotic relationship - Root has to provide space for the fungi to colonize - Certain crops prefer certain fungi and vice-versa
  9. 9. Traits of an individual root critical for plant performance F) Rhizobia bacteria - N fixation (legumes) - Plant receives N, bacteria receives carbon: symbiotic relationship - Root has to provide space for nodules - Certain crops prefer certain rhizobia species and vice-versa
  10. 10. Root trait measurement
  11. 11. Root exudates Carbon-based – byproduct of photosynthesis Mostly sugars, proteins and amino acids (C and N based) Food for soil microorganisms Also communication forms (signalling molecules) between plants, and between plants and microorganisms Disease protection, stress protection
  12. 12. Root traits and soil processes
  13. 13. Root traits and soil structure Increased soil structural properties: - Protect against erosion - Improve water retention - Improve organic matter retention
  14. 14. Root traits and nutrient cycling Knowledge of roots traits improves models when predicting nutrient uptake Which can improve fertilisation schemes when incorporated into a crop management plan
  15. 15. Root traits and carbon cycling Huge gains can be made in: - C sequestration rates - Effective use of cover crops - Belowground knowledge built into rotation plans - C cycling is always couple with mineralisation and plant protection against pathogens
  16. 16. Soil ecology and microorganisms Bardgett & Van der Putten (2014)
  17. 17. Soil ecology and microorganisms Bardgett & Van der Putten (2014) Soil biodiversity is positively correlated with: 1) Soil organic matter content 2) Plant biodiversity 3) Plant productivity A healthy soil ecosystem is an insurance policy when it comes to: 1) Disease outbreaks 2) The stress of climate change 3) Carbon tax regulations
  18. 18. Soil ecology and microorganisms Bardgett & Van der Putten (2014) Diversifying root traits: 1) Offers different root exudates for different microorganisms 2) Root decomposition over the growing season slows C release from the soil (and also feeds microorganisms!) 3) Stabilizes organic matter in the soil, which buffers against extreme conditions
  19. 19. Roots feed soil!
  20. 20. What are the unknowns? Labile C (Root exudates) Stable C Microbes CO2 1) Precise measurements 2) How intercropping and cover-cropping can be used – these are the biggest opportunities for producers here! 3) How surface organic matter management influences roots
  21. 21. What are the opportunities? All of the unknowns! 1) More precise measurements will allow root traits to be built into production models, but also: - Climate change models - Soil health assessments - C sequestration tools - Decision making strategies for rotations and cover-cropping at the farm- and field-level
  22. 22. What are the opportunities? All of the unknowns! 2) Cover-cropping and intercropping are the BIGGEST opportunities for Eastern Ontario to improve soil quality - Especially rotating more fibrous rooting systems (grass) or less nutrient-intensive (oilseed radish) with corn will provide gains for soil OM and biodiversity
  23. 23. What are the opportunities? All of the unknowns! 3) Surface OM interactions with root trait diversification Mature compost, low-hydrophilic DOC Fresh compost, high-hydrophilic DOC
  24. 24. What are the opportunities? All of the unknowns! 4) Precisely how root traits are related to stress tolerance for both crops and microorganisms 0 1 2 3 4 5 Control Drought Control Drought ugCO2perugCadded H. Lanatus R. acetosa
  25. 25. Roots are the opportunity! Future (5-10 years) roots and root traits will be incorporated into on-farm crop management decision making the way tillage and organic matter applications are now. C sequestration opportunities are already here and the more you consider about C, organic matter, roots and ecology, the further ahead of regulations you will be!
  26. 26. Thank you Questions?

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