Harnessing the Power of Soil Biology

1. USDA-NRCS Science 322:49 Harnessing the Power of Soil Biology Dr. Mike Lehman U.S. Dept. of Agriculture -Agricultural Research Service Brookings, South Dakota

2. Microbes Make the Earth Inhabitable In fact, “we are living in a microbial world… American Academy of Microbiology (2008) ...yet, our knowledge of soil microbial ecology borders on primitive”

3. Soil’s where lots of them live A BILLION bacterial cells per soil gram Thousands of “species” Below surface microbial biomass ≈ all combined above ground biomass!

4. Microbes: The Unseen MajorityWhitman (1998) Fungi: millions Algae: 10,000 - 3 million Protozoa: up to 1 million Nematodes: dozens 1 gram of soil In addition to the 1 billion bacteria in one gram of soil:

5. Huge Diversity of the “Unseen Majority”

6. Archaea Bacteria Eukarya Prokaryote Prokaryote Eukaryote Circular DNA 1 chromosome Circular DNA 1 chromosome Linear DNA 4 to 308 chromosomes Ether-linked lipids Ester-linked lipids Ester-linked lipids 70S Ribosome 70S Ribosome 80S Ribosome Gene System II Gene System I Gene System II Methanogens No methanogens No methanogens No chlorophyll Chlorophyll Chlorophyll Grow > 80ºC Grow > 80ºC Grow < 65ºC The Three Domains

8. Alphaproteobacteria Heterotrophs CH4, S, Fe, H2 Oxidizers N2 Fixers Betaproteobacteria Heterotrophs NH3, Mn, S, Fe, H2 Oxidizers N2 Fixers Gammaproteobacteria Heterotrophs NO2-, S, Fe, H2 Oxidizers N2 Fixers Deltaproteobacteria S, NO2- Oxidizers S Reducers Bacterial Predators Functional Diversity: the Proteobacteria

9. We live, as we have always lived, in the “age of bacteria” Steven Jay Gould (1996)

10. A Couple of Simple Questions about the Soil: • What kinds of microbes are there? • What are they doing?

11. Let’s Take a Look

12. Under the Microscope

13. In Culture Less than 0.1% of the microbes present Might not be active ones Probably behaving differently

14. Now recognize the boundless extent of diversity and complexity…..

15. (1977) M. Alexander (1994) (2002) (2006) (2011)

16. (2006)

19. Microbial & Agroecosystems • Organic matter decomposition • Nutrient cycling • Soil structure • Water management • Symbiotic relationships • Pathogen and pest control

20. 2013

21. So, microbes do a lot of stuff, but what about my production system? • How are they affected by my management? • How can I favor the beneficial types and activities?

22. C3 Agricultural Systems • Crop • Rotation Sustainable Production • Conservation • Tillage • Cover • Crops

23. Which handles the elements better? Free Energy, Carbon, Nitrogen Better infiltration More storage Less water erosion Less wind erosion

24. Who Likes Black Dirt? Only if you don’t like food and cover We’re dying over here Not much food No comment It’s too hot! More friends, too It’s too dry! There’s way more food over here And the plow took out my fungal friends And I forgot my shades & sunscreen And, more hiding spots My neighbors were washed & blown away!

25. Using Cover Crops to Improve the Internal Cycling of N • inorganic soil N immobilized on-site in plant biomass • prevents loss: leaching, denitrification, volatilization • Augmented by N-fixation (leguminous cc) • Biomass N gradually mineralizedto ammonium reduces losses • Ammonium oxidized to nitrate (nitrification)

26. Nitrogen Fixation/Mineralization • Convert Atmospheric Nitrogen to Plant Available • Timed release to following Crop 0.14 Cover Crop Nitrogen Mineralization mg N/cm3 0.12 0.1 0.08 0.06 0.04 T3 T2 0.02 T1 0 Clover Fallow Rye Vetch

27. ArbuscularMycorrhizal Fungi ECTOS

29. More volume • Small pores • Increased uptake (1000x surface area) • Enzymes • Chelators • pH

30. AMF Make Plants Drought-Resistant More AMF = More Straws Diverse AMF = More Access

31. AMF reduce erosion Fungal Hyphae Fungal spores, hyphae, and glomalin Root Photo credit: Sara Wright

32. AMF Increase Water Storage Soil Aggregation Soil Structure Water Infiltration & Storage

33. Sorghum at 22 days Plus AMF No AMF

34. Van derHeijden, et al. 1998 Hyphal Length Plant Diversity Soil P Olson Shoot Biomass Plant Tissue P Root Biomass Number of arbuscularmycorrhizal fungal species

35. AMF & Ag Management • Low #s can stress plant • Affected by: • Tillage ↓ • fallow; flooding ↓ • rotation, host plants ↓↑ • P concentration ↓

37. Cropped Field AMF Diversity Prairie

38. Boosting Native Mycorrhizae with Cover Crops

42. P < 0.01 ArbuscularMycorrhizal Fungi (AMF), Ideal, SD, Nov 2010 cover crops: cow pea-winter pea-millet-turnip-radish

43. Clover Oat 4 5 0 Wheat 1 Vetch 1 3 0 1 1 3 0 0 2 0 0 Capturing AMF Diversity with Cover Crops

44. Building Soil Biota • Soil organisms need: • Food • Diverse crop rotation = diverse foods • Continuous cover (perennials, cover crops, long-season crops) = consistent source • Habitat • Stable aggregates that are not destroyed by tillage • Diversity of plants = diversity niches

45. Weed Suppression Pathogen & Pest Protection Soil Structure & Aggregation Plant Growth Promoters Benefits from Soil Microbes Soil Carbon N fixation Nutrient Availability Nutrient Retention

46. Pass-Thru Self-Sustaining Nutrients Pest Protection Yield Yield Lost Lost $ $

47. Progress by Multidisciplinary Research: Acknowledgement and Promotion • Dr. Shannon Osborne • Dr. Wendy Taheri • Dr. David Douds Research funding: U.S. Dept of Agriculture, Agricultural Research Service South Dakota Corn Utilization Council