The Unseen World Beneath Our Feet: The Role of Soil Biota in Supporting Soil Health

Transcription

1 The Unseen World Beneath Our Feet: The Role of Soil Biota in Supporting Soil Health April 20, 2016 Oregon Conservation Education and Assistance Network Meeting, Gleneden Beach, OR Jennifer Moore Kucera, Ph.D. Western Region Soil Health Team Leader USDA-NRCS, Portland, OR United States Department of Agriculture is an equal opportunity provider and employer.

2 "In the end, we conserve only what we love. We will love only what we understand. We will understand only what we are taught." ~ Baba Dioum, Senegalese poet

3 Soil Health: The continued capacity of a soil to function as a vital living ecosystem that sustains plants, animals, and humans Soil Health

4 Tree of Life: Not as you may think

5 Meadow soil is one of the most microbially complex environments on the planet. Dr. Hug In 10 ft 2, the soil has 10 trillion (10 13 ) bacteria 100 billion (10 11 ) fungi 10 billion protozoa 5 million nematodes 100,000 mites 50,000 springtails 5000 insects and spiders 3000 earthworms & potworms 100 snails and slugs 1 vertebrate Lindbo et al Know Soil, Know Life.

6 How much biomass belowground supports the life aboveground? Microorganism Biomass (lbs/acre) Fungi 9760 Bacteria 5840 Actinomycetes 5840 Algae 2720 Earthworms 1840 Protozoa 400 Nematodes 240 Equivalent to ~18 cows ~27,000 lbs per acre!

7 Life exists in the voids between particles Airfilled Space Waterfilled Mineral particles OM SEM image Dr. Lisa Fultz, LSU Philippot, et al. (2013). Nature Reviews Microbiology 11:

8 Life exists in the voids between particles Airfilled Space Waterfilled Mineral particles OM SEM image Dr. Lisa Fultz, LSU Two rules to support soil life: 1. Protect 2. Feed

9 Solutions for Optimal Soil Health Two simple rules: 1. Protect the home (water, air, nutrients) 2. Feed belowground livestock a diverse, year-round diet Minimize soil disturbance Protect the home (aggregate) Maximize diversity (plants, animals, amendments, inoculants ) Feed your livestock Keep the soil covered Protect the aggregate Maximize living roots Feed your livestock

10 Fragmentation and translocation of materials by soil fauna Bacteria and fungi release (mineralize) plant-available nutrients (N, P, S) Soil protozoa, springtails, nematodes, mites, etc. consume bacteria and fungi and mineralize more nutrients (N, P, S)

11 Aggregates are formed by the underground livestock SEM: Dr. Lisa Fultz, LSU Plant root material enmeshed in soil particles Netlike fungal mycelia stabilize micro-aggregates Bacteria with sticky polysaccharides Stabilization of soil structure by actinomycete (bacteria) filaments

12 What happens to organic matter when the soil is disturbed? Temp from 4 to 7 F Grandy et al., Do Productivity and Environmental Trade-offs Justify Periodically Cultivating No-Till Cropping Systems? Agron J. 98:

13 Consequences of aggregate destabilization beyond the C "Ideal Well-structured soil Poorly structured soil

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15 Tillage Choices to Reduce Disturbance No-till Reduced till Timing Frequency Depth Implement Photos: Moore-Kucera, 2016, PMC field day

16 Tillage Choices to Reduce Disturbance

17 Converting part or all of the field to rotation or perennial-based agroecosystems Fungal operational taxonomic units (proportional to system area) Increased Fungal Richness Fungal richness Diversity (diversity) Monoculture crop CTN_1 CTN_2 FRG_CTN Rotations/ Perennial Systems OWB_BER FRG_RC Increased SOM Monoculture crop Fungal richness (diversity) Rotations/ Perennial Systems Davinic, M. 2014, Ph.D. Dissertation

18 Increased fungal diversity led to increased aggregate stability Aggregate Stability (MWD, mm) y = x R² = R = 0.417* Fungal Richness (OTUs) Davinic, M. 2014, Ph.D. Dissertation Fultz, L. 2014, Ph.D. Dissertation

19 Increasing diversity with crop rotations increases aggregate stability, SOC and TN Increased crop diversity, TOC 3.6%; TN 5.3% With cover, TOC 8.5%; TN 12.8% Greatest increases occur when a cover crop was part of rotation McDaniel et al., Ecol Appl 24(3): Tiemann et al., Ecol Letters 18:

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21 Living roots year round increases microbial food (POM) Conventionally managed; chisel plow, no cover, inorg fertilizers, and pesticides Organically managed; legume cover crop

22 Plant type/ genotype alters O bacterial composition 2 ph 3 maize genotypes

23 Plant Roots Communicate with Microbes Via Chemical Signaling

24 Plants signal SOS Bacteria to the rescue!

25 Free N Fertilizer Factories Specialized soil bacteria associated with some plant roots (legumes, alders) supply: lb/ac in natural systems lb/ac in cropland Fava Bean; Moore-Kucera, 2016 Human production: >900 F 20 MPa of pressure (atmosphere is 0.1 MPa) 30 million BTUs of natural gas per ton of N fertilizer 2% of the World s total E consumption is used!

26 Predicted N release from cover crops

27 Historical N Additions May Negatively Affect Nitrogen-Fixing Bacteria

28 Glyphosate increased Xanthomonadaceae (family of proteobacteria) and decreased Acidiobacteria Newman et al., Sci Tot Environ 543:

29 Diverse communities keep the bad guys down Collembolan protection of roots from infection by Rhizoctonia solani 1 protozoan can eat billions of bacteria each day! the vampyrellids (protist), eat fungi (this fungus is a root pathogen (take-all disease). An SCN second-stage juvenile parasitized by the fungus Hirsutella minnesotensis

30 Connecting Biology & Management Bender et al Trends Ecol Evol.

31 Thank You!