Presentation by Steve Diver from the 2012 Resilient Farmer Workshop at the Kerr Center's Cannon Horticulture Plots in Poteau, Oklahoma. Cover crops, soil organic matter, soil food web

1. Managing Organic Matter for
Soil Health & Fertility
Resilient Farmer Workshop
April 28, 2012
Kerr Center for Sustainable Agriculture
Steve Diver, M.Sc.
Agri-Horticultural Consulting
www.agri-synergy.com
Kerr Center for Sustainable Agriculture
Poteau, OK

2. “Without living organisms and organic matter, the birth
of soil is not possible” Kyoichi Kumada (1987)
Objectives for this Workshop
1. What is soil organic matter (SOM)
2. Why is SOM important2. Why is SOM important
3. Vital role of soil biology
4. Contribution of SOM to soil quality and fertilty
5. Managing SOM and soil foodweb “habitat”

3. Organic matter “transformation”

4. Soil Composition
50% Pore Spaces 50% Solids
1-5%

5. Soil Organic Matter
Organic matter is 1-6%
living biomass
10-20%
humus
of total soil mass active fraction
10-20%
humus
60-80%
“The living, the dead, and the very dead”
Vermont Agric Exp Sta Bullletin 135, 1908

6. Soil organic matter
encomposses all
organic components
of the soil:
• Living organisms
• Fresh residues
Image: soils.usda.gov
• Fresh residues
• Decomposing OM
• Stabile OM

7. Soil organic matter
• Living organisms (plant roots,
fungi, bacteria, worms)
• Fresh residues (crop residues,
sloughed roots, dead insects,
animal manures, microbial
secretions)
• Decomposing (decaying
leaves & stalks; partly
recognizable &
partially stabilized OM)
• Stabilized OM
(transformed, recalcitrant OM
or “humus”)
Brady and Weil, 1996SOM dynamic = changing = transforming

8. What is Humus?
Humus is the end result of organic matter decomposition
(break-down) and transformation (build-up) into…
a complex, dark-brown, amorphous-heterogenous (non-
crystalline, non-uniform) structure that no longercrystalline, non-uniform) structure that no longer
resembles the decaying matter of origin, …
is resistant to further microbial decay, and ….
has chemical and physical properties of great importance
to soils and plants.

9. Humus properties:
1. Humus particles become bonded to clay-silicate
surfaces, leading to the formation of clay-humus
complexes.
2. Humus stores and releases soil N.
3. Humus possesses buffering capacity3. Humus possesses buffering capacity
4. Humus possesses cation exchange capacity
5. Humus possesses anion exchange capacity
6. Humus adsorbs pesticides and other agricultural
chemicals.
Soil Fertility Management for Sustainable Agriculture
James F. Power and Rajendra Prasad, CRC Press, 1997

10. % Organic Matter (dry weight) via Lab Test
Image: Rodale Institute
5%OM 1%OM

11. SOM Colorimetric Field Test Using Sodium Hydroxide/EDTA
K-State Soil Test Kit
www.ksre.ksu.edu

12. Active Organic Matter Test — Permanganate Oxidizable C
Image: www.certifiedcropadviser.org

13. Soil quality is the capacity of a soil to function (in a farm or
ecosystem) and thereby sustain productivity, maintain
environmental quality, and promote plant and animal health
Physical Chemical
NPK
Ca
Mn
Mg
S
Fe
BiologicalSoil Health
Aim is to manage
for “balance”
between all three
soil components

14. Learn about Soil Quality Indicators & How they are Measured

15. Soil Organic Matter (SOM) influences all three soil
components & improves soil health
Physical Chemical
Biological
Soil
Organic Matter
Soil Health

16. Function of Soil Organic Matter and the Effect on Soil Properties, CSIRO 2004

17. The Vital Role of Soil Biology
Physical Chemical
BiologicalBiological
“Soil microbial biomass is ‘the eye of the needle’ through
which all organic material that enters the soil must
pass…”
Jenkinson, D.S. 1977. The soil biomass. New Zealand Soil Science
News, 25: 212-218.

18. Foodweb pyramid in one square meter of soil
James B. Nardi, Life in the Soil, 2007

19. SoilSoil MicrofloraMicroflora
Fungi
BacteriaBacteria
Actinomycetes
Fungi
FungiFungi
FungiFungi
after Balser, Univ of Wisconsin
AlgaeAlgae

20. SoilSoil MicrofaunaMicrofauna -- MesofaunaMesofauna
Mite
Nematode
Protozoa
after Balser, Univ of Wisconsin
Springtail

21. Termite
EarthwormEarthworm
PseudoscorpionSoilSoil MacrofaunaMacrofauna
Snail
Vole
Centipede
Balser, Univ of Wisconsin

22. Soil microorganisms live in association with plant
roots and excrete nutrients & sticky substances
VAM mycorrhizal fungi on
plant root: Paula Flynn
Alfalfa root with bacterial
rhizosphere: Jennifer Fox

23. Endo-Mycorrhizal Fungi Excrete Glomalin Glue = Carbon
Photo: Sara Wright, USDA-ARS

24. What’s up with Soil Structure?
Physical Chemical
BiologicalBiological
“Soil structure is a key factor in the functioning of soil,
its ability to support plant and animal life, and moderate
environmental quality with particular emphasis on soil
carbon sequestration and water quality.”
-- Ratan Lal, Ohio State University, 2005

25. EPS – Extracellular
polysaccharides
Sand, silt, clay
Clay-humus
Bacteria & fungi
Soil Aggregate
The interaction of soil particles, biology & biochemistry
Soil Mineral, Organic Matter, Microorganism Interactions, P.M. Huang (2004)

26. Soil Aggregation

27. Photo: João Carlos de Moraes Sá
Universidade Estadual de Ponta Grossa, Brazil
Roots, fungal hyphae, & microbial glues stabilize soil
macroaggregates and promote good soil structure

28. Colony of bacteria on a humus aggregate
EPS – ExopolysaccharidesEPS – Exopolysaccharides
Image: University of Bremen (Germany)|www.microped.uni-bremen.de

29. Fungal hyphae attaches to clay particle via polysaccharide “glue”
Image: University of Bremen (Germany)|www.microped.uni-bremen.de

30. Fungal myceilum stabilizing micro-aggregate
Image: University of Bremen (Germany)|www.microped.uni-bremen.de

31. Actinomycete filaments stabilizing soil structure
Image: University of Bremen (Germany)|www.microped.uni-bremen.de

32. 25 yrs of CT corn25 yrs of CT corn
20 yrs bluegrass,
then 5 yrs CT corn
20 yrs bluegrass,
then 5 yrs CT corn
Water stable aggregate test on rotation plots
Photo: Ray Weil, Univ of Maryland

33. “Dispersed”
Water Stable
Aggregates
1.0% C 1.4% C
Adding Water to Soil Samples
25 yrs of25 yrs of
conventionalconventional
corncorn
25 yrs of25 yrs of
conventionalconventional
corncorn
20 yrs of bluegrass,
then 5 yrs
conventional corn
20 yrs of bluegrass,
then 5 yrs
conventional corn
Photo: Ray Weil, Univ of Maryland

34. Water-Stable Soil Aggregates
Conv Tillage
No-Till
NRCS Demonstration, Texas

35. The Role of OM in Soil Fertility
Physical Chemical
BiologicalBiological
Cation exchange capacity
Anion exchange capacity
Nitrogen mineralization
Slow-release fertility
Source of N, P, K, S, micronutrients

36. Nitrogen Released from Organic Matter
In surface 7-inch depth of soil (2,000,000 lbs)
% OM Stable OM lbs/ac Total N lbs/ac Lbs N/ac Released
in Silt Loam Soil
1.0 20,000 1,000 15-30
1.5 30,000 1,500 22-45
2.0 40,000 2,000 30-60
2.5 50,000 2,500 37-75
3.0 60,000 3,000 45-90
3.5 70,000 3,500 52-100
4.0 80,000 4,000 60-120
4.5 90,000 4,500 67-135
5.0 100,000 5,000 75-150
Soil Fertility and Corn Production, Univ of Missouri Agr Exp Sta Bull 583 (1952)

37. Negatively-charged clay platelets attract
positively-charged cations; “adsorption”
Colloidal = glue-like
Managing Healthy Sports Fields, Paul D. Sachs, 2004

38. Clay-Humus, Seat of Soil Fertility
Clay-humus architecture with:
Massive surface area
Negatively-charged exchange sites
Organo-mineral complex
Siegfried Luebke, CMC Compost Group

39. Managing Organic Matter and
Soil Foodweb “Habitat”
Keep the Soil Covered (year-round)
Living crops, crop residues, living cover crops,
killed cover crop mulches, organic mulcheskilled cover crop mulches, organic mulches
Feed the Soil (supply carbon & mineral foods)
Green manures, cover crop roots,
composts, “carbon pulses” (liquid fish,
molasses), minerals (P, K, Ca, Mg, S)

40. Managing Organic Matter and
Soil Foodweb “Habitat”
Reduced Tillage & Common Sense Tillage
Minimum-till, no-till, surface cultivation
Tillage with Humus Management = OK
Tillage neglecting Humus Management = Avoid
Bio-Complexity – Above & Below Ground
Cover crop mix, crop diversity, intercropping

41. Five Things to Know About Cover Crops
1. Multiple Functions & Uses in Cropping System
2. Plant Species Choices & Mixtures
3. Promote Growth of Cover Crop Biomass
4. Surface Mulch & Green Manuring Options4. Surface Mulch & Green Manuring Options
5. Promote Break-Down (organic matter
digestion) & Build-Up (humification)

42. Keep the Soil Covered
Baled mulch from cereal cover crop
Potomoc Vegetable Farm, Virginia

43. No-Till Soybeans in Brazil
Photo: João Carlos de Moraes Sá
Universidade Estadual de Ponta Grossa, Brazil

45. A Guide to Green Manure, Cover Crops and Cultivated Legumes by Ralph Waldo Earthworm

46. Cover Crops for
Every Season
Buckwheat
Crimson Clover
Cool-season
Warm-season

47. Image: Joel Gruver, NCSU-CEFS
Rapeseed
Crimson clover
Rye
Wow ! Look at that root !

48. Air above each acre of earth
contains 36,000 tons (72M lbs)
of Nitrogen
Rhizobium nodules on legume – N fixationRhizobium nodules on legume = N fixation

49. Bio-Complexity = Above & Below Ground

50. Peregrin Farm, NC
Movable Hoop House with Cover Crops

51. Roller-Crimper, USDA-ARS in Alabama
Widely practice in South America using Black Oats cover crop

52. Organic No-TillOrganic No-Till Corn with Roll-Plant System
Image: Jeff Moyer, Rodale Institute

53. Mechanical-Killed Cover Crop Mulch
Image: Jeff Moyer, Rodale Institute

54. Sicklebar Mower – Mechanical-Killed Cover Crops
Image: George Kuepper, Kerr Center for Sustainable Agriculture

55. Photo: Ray Weil, Univ of Maryland
What’s the difference between these two farms?
Mid-Atlantic Drought, 1996-97

56. Conservation tillage
Photo: Ray Weil, Univ of Maryland
Keeping the Soil Covered
Conventional tillage
Mid-Atlantic Drought, 1996-97

57. The First Book of Farming (1905) by Charles L. Goodrich

58. Green Manuring
Spading Machine = SOM incorporation
Potomoc Vegetable Farm, Virginia

59. Effects of SOM incoporation
Add
organic
matter
Increased
biological
activity
& diversity
Decomposition
Pore
Microbial diversity reduces
soil-borne diseases
Nutrients
released
Aggregation
increased
Pore
structure
improved
Humus formation
Tilth improved
HEALTHY PLANTS

60. Humus management practice: bio-inoculating green manures
& crop residues
Pfeiffer Field & Garden Spray,
Josephine Porter Institute, over
50 species of SOM digesting and
humifying microbes
Gerald Wiebe, Manitoba (Canada),
compost extract with microbial food
additives to enhance microbial
digestion of crop residue incorporation

61. Compost is a Managed Process of
Organic Matter Decomposition &
Humification
C:N ratio Particle size
Mixing Porosity
Temperature Moisture
Aeration Microbes
Transforming raw organic matter into humus

62. Transformation of raw organic matter into stabilized
compost occurs in a succession of temperature &
biological processes
Phases of Compost Heating, Cooling, and Maturation
FiBL / IFOAM Training Manual on Organic Agriculture in the Tropics

63. Compost Rate of Application
High
10-15 tons per acre (20-30 cu yds)
RegularRegular
5 tons per acre (10 cu yds)
Low
2-3 tons per acre (4-6 cu yds)

64. Dairy Manure Compost (Texas)

65. SEM MicroscopicSEM Microscopic View ofView of
CompostCompost ParticleParticle
Miloslav Kaláb, Guelph Food Research Centre

66. Worm CompostWorm Compost
Synergism:
NutrientsNutrients
Microorganisms
Humic acids
Hormones
Enzymes
Microbial metabolites

67. Five Principles of Agriculture for the Humid
Tropics by Roland Bunch
1. Maximize organic matter production
2. Keep the soil covered
3. Use zero tillage3. Use zero tillage
4. Maximize bio-diversity
5. Feed the crops largely through the mulch
• GM/CC Mulches + Zone-Till + Agroforestry
• “Nutrient Access” (Ana Primavesi) vs
“Nutrient Quantity” Concept

68. USDA – Natural Resources Conservation Service
“Goals for SOM Management”
1. Till the soil as little as possible1. Till the soil as little as possible
2. Grow as many different species of plants as possible
through rotations & diverse mixtures of cover crops
3. Keep living plants in the soil as long as possible with
crops & cover crops
4. Keep the soil surface covered with residue year
round

69. Presented at the Kerr Center for Sustainable Agriculture, a
non-profit organization in southeast Oklahoma, as part of a
USDA-NRCS Conservation Innovation Grant.
Steve Diver, M.Sc.
Agri-Horticultural Consulting
www.agri-synergy.com
steved@ipa.net