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Managing Organic Matter for Soil Health and Fertility


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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

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Managing Organic Matter for Soil Health and Fertility

  1. 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 Kerr Center for Sustainable Agriculture Poteau, OK
  2. 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. 3. Organic matter “transformation”
  4. 4. Soil Composition 50% Pore Spaces 50% Solids 1-5%
  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. 6. Soil organic matter encomposses all organic components of the soil: • Living organisms • Fresh residues Image: • Fresh residues • Decomposing OM • Stabile OM
  7. 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. 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. 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. 10. % Organic Matter (dry weight) via Lab Test Image: Rodale Institute 5%OM 1%OM
  11. 11. SOM Colorimetric Field Test Using Sodium Hydroxide/EDTA K-State Soil Test Kit
  12. 12. Active Organic Matter Test — Permanganate Oxidizable C Image:
  13. 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. 14. Learn about Soil Quality Indicators & How they are Measured
  15. 15. Soil Organic Matter (SOM) influences all three soil components & improves soil health Physical Chemical Biological Soil Organic Matter Soil Health
  16. 16. Function of Soil Organic Matter and the Effect on Soil Properties, CSIRO 2004
  17. 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. 18. Foodweb pyramid in one square meter of soil James B. Nardi, Life in the Soil, 2007
  19. 19. SoilSoil MicrofloraMicroflora Fungi BacteriaBacteria Actinomycetes Fungi FungiFungi FungiFungi after Balser, Univ of Wisconsin AlgaeAlgae
  20. 20. SoilSoil MicrofaunaMicrofauna -- MesofaunaMesofauna Mite Nematode Protozoa after Balser, Univ of Wisconsin Springtail
  21. 21. Termite EarthwormEarthworm PseudoscorpionSoilSoil MacrofaunaMacrofauna Snail Vole Centipede Balser, Univ of Wisconsin
  22. 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. 23. Endo-Mycorrhizal Fungi Excrete Glomalin Glue = Carbon Photo: Sara Wright, USDA-ARS
  24. 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. 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. 26. Soil Aggregation
  27. 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. 28. Colony of bacteria on a humus aggregate EPS – ExopolysaccharidesEPS – Exopolysaccharides Image: University of Bremen (Germany)|
  29. 29. Fungal hyphae attaches to clay particle via polysaccharide “glue” Image: University of Bremen (Germany)|
  30. 30. Fungal myceilum stabilizing micro-aggregate Image: University of Bremen (Germany)|
  31. 31. Actinomycete filaments stabilizing soil structure Image: University of Bremen (Germany)|
  32. 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. 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. 34. Water-Stable Soil Aggregates Conv Tillage No-Till NRCS Demonstration, Texas
  35. 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. 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. 37. Negatively-charged clay platelets attract positively-charged cations; “adsorption” Colloidal = glue-like Managing Healthy Sports Fields, Paul D. Sachs, 2004
  38. 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. 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. 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. 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. 42. Keep the Soil Covered Baled mulch from cereal cover crop Potomoc Vegetable Farm, Virginia
  43. 43. No-Till Soybeans in Brazil Photo: João Carlos de Moraes Sá Universidade Estadual de Ponta Grossa, Brazil
  44. 44. A Guide to Green Manure, Cover Crops and Cultivated Legumes by Ralph Waldo Earthworm
  45. 45. Cover Crops for Every Season Buckwheat Crimson Clover Cool-season Warm-season
  46. 46. Image: Joel Gruver, NCSU-CEFS Rapeseed Crimson clover Rye Wow ! Look at that root !
  47. 47. 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
  48. 48. Bio-Complexity = Above & Below Ground
  49. 49. Peregrin Farm, NC Movable Hoop House with Cover Crops
  50. 50. Roller-Crimper, USDA-ARS in Alabama Widely practice in South America using Black Oats cover crop
  51. 51. Organic No-TillOrganic No-Till Corn with Roll-Plant System Image: Jeff Moyer, Rodale Institute
  52. 52. Mechanical-Killed Cover Crop Mulch Image: Jeff Moyer, Rodale Institute
  53. 53. Sicklebar Mower – Mechanical-Killed Cover Crops Image: George Kuepper, Kerr Center for Sustainable Agriculture
  54. 54. Photo: Ray Weil, Univ of Maryland What’s the difference between these two farms? Mid-Atlantic Drought, 1996-97
  55. 55. Conservation tillage Photo: Ray Weil, Univ of Maryland Keeping the Soil Covered Conventional tillage Mid-Atlantic Drought, 1996-97
  56. 56. The First Book of Farming (1905) by Charles L. Goodrich
  57. 57. Green Manuring Spading Machine = SOM incorporation Potomoc Vegetable Farm, Virginia
  58. 58. 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
  59. 59. 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
  60. 60. 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
  61. 61. 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
  62. 62. 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)
  63. 63. Dairy Manure Compost (Texas)
  64. 64. SEM MicroscopicSEM Microscopic View ofView of CompostCompost ParticleParticle Miloslav Kaláb, Guelph Food Research Centre
  65. 65. Worm CompostWorm Compost Synergism: NutrientsNutrients Microorganisms Humic acids Hormones Enzymes Microbial metabolites
  66. 66. 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
  67. 67. 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
  68. 68. 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