great soil-great gardens i basic soil science · great soil-great gardens i . basic soil science ....

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