great soil-great gardens i basic soil science · great soil-great gardens i . basic soil science ....
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Materials developed by: Karen A. Plumley, Ph.D. Research Director, Alliance for Low Input Sustainable Turf
Soils Instructor, Rutgers Golf Turf Management School
Great Soil-Great Gardens I Basic Soil Science Brad Park, Rutgers University
Great Gardens – Great Soil I Basic Soil Science
I. What is Soil? II. Physical Properties of
Soil III. Soil Organic Matter IV. Soil Water V. Chemical Properties VI. What are the properties
of YOUR soil? VII. Web Resources
What is Soil? • A natural body covering the
earth’s surface in which plants grown
• Comprised of mineral and organic materials
• Formed naturally by the combined effects of climate, living organisms, parent material, topography and time.
What is Soil?
THE FUNCTIONS OF SOIL
1. Medium for Plant Growth - Provides ventilation of gases i.e. CO2 and O2 - Stores water & supplies nutrients - Modifies temperature - Provides support - Seed germination bed 2. Water Supplies - Storage / Filtration 3. Habitat for Soil Organisms who recycle organic waste
How much soil feeds the world? •75 % of earth’s surface is water… which leaves 25% •50% of that 25% is desert, polar or mountainous… which leaves 12.5% •40% of that 12.5% is too steep, too infertile, too rainy or too rocky… which leaves 7.5%
Soil formation is simultaneously: Breakdown of old Synthesis of new Losses Additions Translocations
Each soil is a unique individual that develops as a result of the climate, living organisms, parent material, topography and time.
How do soils form?
A Natural, Forest Soil Profile
O
A
E
B
Parent Material
Horizons = layers
Clay Silt Sand
Gravel Very Fine
Fine Medium Coarse Very Coarse
0.002 mm 0.05 mm 2.0 mm
II. SOIL PHYSICAL PROPERTIES - Texture Texture = % sand + % silt + % clay
Sand II. SOIL PHYSICAL PROPERTIES - Texture
• Broken down rock frags
• Chemically inert compared with clay and OM
• Promote air movement and drainage
Silt
Clay
II. SOIL PHYSICAL PROPERTIES - Texture
• Broken rock fragments or synthesized in soil
• Chemically Reactive
• Increase soil’s water and nutrient hold capacity
12 Textural Classes
Aggregate = secondary soil particles create porosity of soil
www.emc.maricopa.edu/.../BioBookPLANTHORM.html
II. SOIL PHYSICAL PROPERTIES - Structure
Aggregate Shape
http://ltpwww.gsfc.nasa.gov
Granular
Blocky
II. SOIL PHYSICAL PROPERTIES - Structure
Prismatic
Platey
Promote air movement / drainage Resist compaction
Inhibit air movement / drainage Easily compacted
• Aggregates are destroyed by:
• Cultivation (too wet) • Compaction
• Aggregation is promoted by:
• Root growth • Addition of organic material
Importance of Aggregates
II. SOIL PHYSICAL PROPERTIES - Structure
• Total volume of pores
• Filled with water and air in constantly changing proportions
Porosity II. SOIL PHYSICAL PROPERTIES - Structure
Compaction II. SOIL PHYSICAL PROPERTIES - Porosity
II. SOIL PHYSICAL PROPERTIES - Color
Gives soils their dark color.
III. SOIL ORGANIC MATTER
• Biological origin
• Source: – Live biomass – Non-living (various stages
of decomposition)
• Humus: relatively stable end product of decomposition
III. SOIL ORGANIC MATTER
Constantly changing form as soil ‘critters and microbes’ consume it …
In one teaspoon of “healthy” soil there should be: – 600 million bacteria – three miles of fungal hyphae – 10,000 protozoa – 20 to 30 beneficial nematodes in a teaspoon of soil
Dr. Elaine R. Ingham, Soil Food Web
Selman Waksman • Waksman coined the term
antibiotics • It was at Rutgers that
Waksman's team discovered streptomycin and eomycin
• Streptomycin = first antibiotic to cure tuberculosis
• Received the Nobel Prize for the discovery of streptomycin
– Enhances biological activity – Improves cation exchange (nutrient holding and release) – Increases water holding capacity – Increases porosity and infiltration – Improves soil structure and tilth – Reduces crusting and erosion
Benefits of Organic Matter III. SOIL ORGANIC MATTER
• Without water life isn't possible • Solvent for every chemical reaction that makes up life • Evaporation on the leaf cools the plant • Required in photosynthesis • Needed for cell expansion and growth • Plants use water to maintain their shape
IV. SOIL WATER
Function of Water in Plants
Qualitative Description of Soil Wetness II. PROPERTIES OF WATER Plant-centric Description of Soil Wetness PLANT AVAILABLE WATER
Plant Unavailable Water • Water in soil beyond PWP • Drought tolerant plants cannot extract water beyond -15 bars
Plant Unavailable Water • Water between saturation and FC
Plant Available Water • Water between FC and PWP
• Water Holding Capacity – Amount of water a soil can retain is influenced by: Texture Structure Organic Matter – Can be increased by raising organic matter levels
sand < silt < clay
IV. SOIL WATER - Storage
II. PROPERTIES OF WATER IV. SOIL WATER - Movement 1. Texture and Pore Size • Size and total pore space • Rate of movement through soil • Adsorptive forces vs. gravitational forces
II. PROPERTIES OF WATER
2. Soil Structure: Allows gravitational water to drain more quickly
Granular Prismatic Blocky Platey
IV. SOIL WATER - Movement
V. SOIL CHEMICAL PROPERTIES - Fertility
an important plant-growth factor that can be managed Alkaline pH above 7.0 Neutral pH 6.0-6.5 Acid (example) pH below 6.0 Brady & Weil, 1999
Soil pH pH Degree of Acidity or Alkalinity
Alkaline pH above 7.0 Neutral pH 7.0 Acid (example)
pH below 7
V. SOIL CHEMICAL PROPERTIES- pH
Brady & Weil, 1999
♦Affects nutrient availability (solubility)
♦Aluminum toxicity damages roots at low pH ♦Direct damage also possible at high pH
Effects of Soil pH
Cation Exchange Capacity • A measure of soil fertility and nutrient retention • Higher CEC = higher fertility
V. SOIL CHEMICAL PROPERTIES - CEC
Cation- a positively charged ion NH4
+ K+ Ca2+ Fe2+
Cation Exchange Capacity V. SOIL CHEMICAL PROPERTIES - CEC
• Clay and humus have negative charges on their surface
• Cations are attracted and held clay and humus • Once attracted, cations are protected from
leaching • Provide nutrient reserve for plants when they
are ‘exchanged’ into soil solution • Dependent on texture and OM
Cation Exchange Capacity – protects nutrient from leaching
Sandy Soil Clay Soil
VI. What are the properties of YOUR soil?
Soil TEST!
• Evaluate nutrient levels
• Determine soil pH
• Receive most appropriate recommendation for fertilizer & lime
• Soil Testing kits available at county offices of Rutgers Cooperative Extension: njaes.rutgers.edu/soiltestinglab
VI. What are the properties of YOUR soil?
Soil TEST
VI. What are the properties of YOUR soil?
Web-based copies may be found at: http://websoilsurvey.nrcs.usda.gov/app/
Glossary of Soil Science Terms Soil Science Society of America https://www.soils.org/publications/soils-glossary/ Soil Formation USDA http://soils.usda.gov/education/facts/formation.html/ Lessons - Soil Genesis and Development Plant & Soil Sciences eLibraryPRO http://passel.unl.edu/pages/index2col.php?alllessons=1&tag=Soil+Genes+and+Development
VII. WEB RESOURCES
Soil Surveys on the Web USDA http://websoilsurvey.nrcs.usda.gov/app/
“How can I stand on the ground every day and not feel its power?
How can I live my life stepping on this stuff and not wonder at it?”
- William Bryant Logan