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  • 1. Soil Composition & Ferterlizers
    Northridge Garden Guild
    June 29, 2010
    Materials are a condensed version of information provided by the USU extension service
  • 2. Soil Composition
    Jerry L. Goodspeed
    Utah State University Extension
  • 3. USDA NRCS
    Soil – what’s in it?
  • 4. Why is soil important?
    Like humans, plants thrive in a healthy environment
    Good soil provides nutrients, oxygen and water to plants without stress
    Weak plants are more susceptible to disease and insects
  • 5. Components of Soil (by volume)
    and nutrient transport)
    (Primary soil particles
    and nutrients for plants)
    (Soil structure and
    nutrients for plants)
    (Oxygen to roots)
  • 6. Different soil profiles
    What does your soil look like?
  • 7.
  • 8.
  • 9. Topsoil-subsoil Characteristics
    -high organic matter
    -low salts
    -high nutrients
    -low organic matter
    -high clay and/
    or lime
    -high salts
    -high pH
  • 10.
  • 11. Individual Soil Properties
  • 12. Soil Texture
    The Percentage of sand, silt and clay in the soil
  • 13. The Effect of Particle Size
    Sand particles
    Clay particles
    Air flow
    Water flow
  • 14. Determining Soil Texture
    By feel
    Soil test
    jar method
    Fill a 1-quart jar ¼ full of soil
    Fill the jar ¾ full of water
    Shake very well to suspend soil
    Place on a flat surface and allow soil to settle
  • 15. Clay
  • 16.
  • 17. Texture Effects on Soil’s Physical Properties
    Textureavailable waterAerationDrainageCompaction
    Silt loam
    Clay loam
  • 18. Treating Soil Texture “Problems”
    Too much sand?
    You are lucky
    Adjust irrigation accordingly
    Select drought tolerant plants
    Too much clay?
    Good luck!
    Select plants tolerant of poor drainage, lack of oxygen
    Either case: induce soil structure
  • 19. Introduction of Organic Matter
    The combination of sand, silt and clay combined with organic matter creates secondary particles called aggregates
  • 20. Compaction
    Destroys soil structure
    Seals off soil surface
    Water runs off instead of into soil – drought results
    Air can’t enter or escape soil -
    Roots can’t penetrate the soil
    Stress – plants die
  • 21. Soil Compaction
  • 22. Preventing Compaction
    Grates, bricks, sidewalks in high-use areas
  • 23. Treating compaction
    Eliminate the cause:
    Fence, hedge, signs
    Add organic matter to soil
    Aerate or till the soil
  • 24. Aeration
    Hollow Tine Aerator
    “Instant air spaces” for water and oxygen
    movement into the plant root zone
  • 25. Soil Drainage
  • 26. Poor Drainage Problem
    Prevent compaction?
    Add organic matter
    Install subsurface drainage system
    Provide drainage ditches
    Develop raised beds
    Use precise water management
  • 27. Excessive Drainage Problem
    Very sandy soil
    Consider sunken beds
    Add extra organic matter
    Precise water management
  • 28. Amending Soil with Organic Matter
    Improves drainage
    Improves water-holding capacity
    Reduces compaction
    Provides nutrients to plants
    Improves soil “tilth”
    (ease of tillage, working with a soil)
    Lowers soil pH
  • 29. How much organic matter should I add?
    How much is already there?
    Native Utah soils ~ 0.25 to 2.0%
    Ideal soils 5-10%
    Are you satisfied with the current condition of your soil?
    Add some organic matter to maintain soil conditions
    Should I add sand to my clay soil?
  • 30. Adding/Preserving Organic Matter
    Grow plants
    Mulch around perennials
    Add extra organic matter to gardens and other annual planting areas
  • 31. Sources of Organic Matter
    Wood Residues
    Chips/sawdust/bark materials
    Add 1 to 2 lbs of nitrogen per 100 lbs of material
    Grass clippings or green residues
    Can’t go wrong with these
    Allow to dry
    Composts and animal manure
    • Watch for salts and weed seeds
  • How much Organic Matter Should I add?
    Single application
    One inch per year for normal applications in annual areas(new site needs significant improvement)
    1 inch of material = 3 cubic yards spread over a 1,000 square foot area
  • 32. Summary
    Understand what you have
    Figure out what you need
  • 33. Fertilizers
    Basic Master Gardener
    Jerry L. Goodspeed
    Utah State University
  • 34. 16 Essential nutrients
    Macronutrients (large quantities):
    oxygennitrogen phosphorus
    hydrogenpotassium sulfur
    carbon calcium magnesium
    Micronutrients (small quantities):
    copper manganese
    chlorine molybdenum
    nitrogen Phosphorus Potassium
  • 35. Sources of nutrients
    Inorganic/Synthetic fertilizers
    Organic Fertilizers
    Manures composts, and other organic materials
    Green manures (legumes and others)
  • 36. Fertilizer label
    Three numbers always appear on the label
    1. % Nitrogen (N)
    2. % Phosphorus (P)
    3. % Potassium (K)
  • 37. Just A few N-P-K labels out there
  • 38. Selecting a fertilizer
    What nutrients are needed?
    Soil test
    What ratio of nutrients are needed?
    Nitrogen alone or a “complete” fertilizer?
    Established landscapes need nitrogen annually; few landscapes need other nutrients
    Are extras needed?
    cost factor: extras increase cost
  • 39. Soil testing
  • 40. Soil testing…
    …prior to planting: ensures good success – especially in new landscapes
    …diagnose problems
    …every 2 to 3 years to monitor soil environment
  • 41. Soil sampling
    Sample areas with different soils
    6-inch depth in turf
    12-inch depth around woody vegetation and in gardens
    Combine 4 to 6 sub-samples from the area for each sample submitted
  • 42. Soil Test Report
  • 43. Methods of application
    Broadcast – evenly distributed on surface
    Banding – applied in a narrow band on surface or in furrow opened adjacent to plant row
    Foliar – applied in liquid form
  • 44. Spreaders
  • 45. Organic nutrient sources
    Much lower concentration of nutrients
    Example: 2-2-2 for composts
    Good sources of organic matter
    May need to supplement with inorganic nitrogen fertilizer
  • 46. Green manures
    Plants grown for the sole purpose of “storing” nutrients or producing nutrients (nitrogen) and organic matter for later use in the garden
    Legumes (peas, beans, vetch, alfalfa)
    Small grains (rye, oats, barley, wheat)
  • 47. Other considerations
    Combine inorganic and organic nutrients
    Practice crop rotation in garden
    Return as much organic matter as possible to annual planting areas
  • 48. Soil pH and Iron Chlorosis
  • 49. Soil pH
    Soil pH: the degree of acidity or alkalinity of soil
    The pH scale:
    2 4 6 8 10 12
  • 50. Causes of iron chlorosis
    High lime soils
    Buffer pH in 7.8-8.0+ range
    Planting acid-loving plants in Utah
    “Aggravating factors”
    Cold soils
    Soil compaction
    Other stresses
  • 51. Major pH problem:iron chlorosis
  • 52. Solutions to iron chlorosis problem
    Select iron efficient plants
    Treat with iron
    Change soil pH?
  • 53. pH tolerant = iron efficient plants
  • 54. Soil salinity
  • 55. Soil salinity = soluble salts in soil
    Salts inhibit plant growth
    Salts cause “chemical drought”
    Visual diagnosis: salt crusting/salt burn
    Soil test diagnosis:
    Electrical conductivity (EC)
    EC > 2 deciSiemens/meter is a saline soil for horticulture uses
  • 56. Examples
  • 57. Sources of salts
    Residual salts in new development areas
    Irrigation water
    natural sources
    water softeners
    Deicing salts (road throw and sidewalks)
    Over-application of fertilizers and/or manures and composts
  • 58. Solutions to salt problems
    Control the source:
    water, fertilizer, manure runoff, other?
    Clean up the problem:
    Remove salts by leaching with water