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Getting Down and Dirty Getting Down and Dirty With SoilWith Soil

Developed by :Developed by :

Hudson Minshew, Oregon State University Extension ServiceHudson Minshew, Oregon State University Extension Service

Susan Donaldson, University of Nevada Cooperative ExtensionSusan Donaldson, University of Nevada Cooperative Extension

USDA NRCS

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What you’ll learn todayWhat you’ll learn todaySoil texture and

structure

The living soil

Understanding soil erosion

Reducing soil erosion

Improving your soil

Taking a soil sampleNRCS, Mont.

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What describes a good soil?What describes a good soil?Drains well

Doesn’t crust after planting

Soaks up heavy rains with little runoff

Stores moisture for drought periods

Has few clods and no hardpan

Resists erosion and nutrient loss

Produces healthy, high quality crops

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Soil is a foundation for:Soil is a foundation for:Growing plants

and crops

Supporting buildings, roads and bridges

Housing a septic system

Storing and filtering water

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How are soils formed?How are soils formed?

A. Miller

Soil Soil horizonshorizons

USDA NRCS

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Compare horizonsCompare horizons

OSU Extension Service

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What are soils made of?What are soils made of?

Minerals

Air

Water

Organic matter (humus)

www.statlab.iastate.edu

Soil Soil mineralsminerals

A. Miller

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Water = 20-30%

Air = 20-30%

Mineral fraction

(sand, silt,clay) = 45-50%

Organics = 0-5%

Composition of a loam soilComposition of a loam soil

The soil textural triangle

A. Miller

NRCS, Bozeman Mont.

Textural Textural triangletrianglefor the for the

graphically graphically challengedchallenged

Texture by feel: SandTexture by feel: Sand

Adapted from NRCS, Bozeman Mont. by A. Miller

Texture by feel: Loamy sandTexture by feel: Loamy sand

Adapted from NRCS, Bozeman Mont. by A. Miller

Texture by feel: Loams and claysTexture by feel: Loams and clays

Adapted from NRCS, Bozeman Mont. by A. Miller

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Why determine soil texture?Why determine soil texture?

Soil texture influences:

Water intake rates

Water-storage capacity

Ease of tillage

Amount of aeration

Soil fertility

In this experiment, an equal amount of water was applied to three soil types.

NRCS, Bozeman, Mont.

Soil texture affects drainageSoil texture affects drainage

Note the amount of water that drained from the sandy loam soil.

NRCS, Bozeman, Mont.

Soil texture affects drainageSoil texture affects drainage

Less water has drained from the silty clay loam soil.

Soil texture affects drainageSoil texture affects drainage

NRCS, Bozeman, Mont.

The loam soil drained almost as much as the sandy loam.

Soil texture affects drainageSoil texture affects drainage

NRCS, Bozeman, Mont.

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Platy structure

Granular structure

www.statlab.iastate.edu/soils/

Soil structure:Soil structure:How particles are grouped together

into stable collections

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OSU Extension Service

Good quality soil has:Good quality soil has:

Good aeration

Good drainage

Good tilth, meaning they’re easy to work

Lots of organic matter

Lots of organisms

USDA NRCS

The living soilThe living soil

wormworm

USDA NRCS

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Soil organic matter consists of:Soil organic matter consists of:

Living organisms

Dead organisms

Plant matter

Other decomposing organic materials UNCE, Reno, Nev.

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Benefits of soil organic matterBenefits of soil organic matter

Increased water- and nutrient-holding capacity

Formation of soil into stable aggregates

Reduced soil compaction

Improved water infiltration

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What threatens my soil?What threatens my soil?

NRCS, Bozeman, Mont.

Water drop impactWater drop impact

USDA NRCS

Sheet Rill Gully

Types of water erosionTypes of water erosion

A. Miller

Severe water erosion Severe water erosion occurred during the “dust occurred during the “dust

bowl” era in the 1930sbowl” era in the 1930s

USDA NRCS Photo Gallery

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Signs of water erosionSigns of water erosion

Small rills and channels on the soil surface

Soil deposited at the base of slopes

Sediment in streams, lakes, and reservoirs

Pedestals of soil supporting pebbles and plant materials

ErosionErosionNote both compaction and rill erosion

OSU Extension Service

Gully erosionGully erosion

OSU Extension Service

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Damage from erosion can cause loss of property and jeopardize safety

NRCS, Bozeman, Mont.

Streambank erosionStreambank erosion

UNCE, Reno, Nev.

NRCS, Bozeman, Mont.

Wind erosion

Wind erosion

NRCS, Bozeman, Mont.

Wind erosion

NRCS, Bozeman, Mont.

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How to reduce soil erosionHow to reduce soil erosionUse common senseRetain existing vegetation whenever

possible, or add protective cover such as cover crops or mulch and plant litter

Time grading, construction and tillage to minimize exposure of soil to erosive forces

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How to reduce soil erosionHow to reduce soil erosion

Fit development to the terrainDivert runoff away from bare

areas Create a barrier to the erosive

agentKeep runoff velocities low

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How to reduce soil erosionHow to reduce soil erosion

Minimize length and steepness of slopes

Trap sediment on-siteReduce tillage and number of

passesMaintain drainageways to handle

increased runoff

Use a buffer Use a buffer strip between strip between water’s edge water’s edge

and cultivated or and cultivated or grazed land to grazed land to help catch soil help catch soil particles that particles that may erode.may erode.

USDA ARS

Ungrazed or unharvested buffer stripsUngrazed or unharvested buffer strips

OSU Extension Service

Create barriers

Reduce velocities

Trap sediment

OSU Extension Service

Minimize length and steepness of slopes

Slow runoff velocities

Increase infiltration

Contours and terracesContours and terraces

OSU Extension Service

Sometimes the solution involves engineering

Overgrazing and letting water run across the disturbed ground is a surefire way to increase erosion

Conservation District, Bozeman, Mont.

Plant windbreaks to decrease soil loss from wind erosion

NRCS, Bozeman, Mont.

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Soil qualitySoil quality

An assessment of the capacity of a soil to:

– Sustain plant and animal productivity

– Maintain or enhance water and air quality

– Support human health and habitation

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Soil qualitySoil quality

Soils vary naturally in their capacity to function, so soil quality is specific to each type of soil

Soil quality is the dynamic quality of the soil. Soil quality is affected by management, such as increasing organic matter (increases quality) or tilling when wet (decreases quality)

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How can I manage my soils to How can I manage my soils to improve them?improve them?

Avoid compaction by:• Reducing tillage of wet soils

• Reducing traffic on wet soils

Increase the organic matter content by:

• Adding compost and manure

• Growing and tilling in cover crops (green manure)

Maintain cover with vegetation

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Avoid walking or driving on wet soil

OSU Extension Service

Composition of a compacted soilComposition of a compacted soil

Solid

Air

Water

Note the reduced air space in a compacted soil.

Before After

70%50%

Add soil organic matterAdd soil organic matter

OSU Extension Service

Manure spreaders make the job of applying manure as an organic

matter amendment easier

OSU Extension Service

Add compostAdd compost

OSU Extension Service

Household vegetable debris and grass clippings can also be used

to make compost

UNCE Reno, Nev.

Cover crops

OSU Extension Service

How do How do I know I know what to what to add to add to my my soil???soil???

A. Miller

Test your soil!Test your soil!

UNCE, Reno, Nev.

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What information does a soil What information does a soil test provide?test provide?

Soil textural analysis

pH and salts

Soil nutrient content

Fertilizer recommendations

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A fertile soil has:A fertile soil has:

The right kinds and amount of nutrients to grow pasture or crops

Low salinity and sodium

Close to a neutral pH (about 7)

Plenty of organic matter

USDA NRCS

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How often should I take a soil How often should I take a soil sample?sample?

Prior to seeding a pasture

At least every 3 years for established pastures

Frequently enough to make good decisions on fertilization

When it is cost effective

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How to take a sampleHow to take a sample

First, select the site. Your soil sample should represent only one soil type or soil condition.

OSU Extension Service

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Each sample should consist of sub-samples taken from about 15 locations within the same soil type or sampling area.

OSU Extension Service

How to take a sampleHow to take a sample

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Use the “slice” method for a representative sample.

UNCE, Reno, Nev.

How to take a sampleHow to take a sample

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SummarySummary

Know your soil texture

Remember that the soil is a living system and you need to support that environment

Erosion is costly - protect your soil with vegetation or mulches

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SummarySummaryContinually improve the soil quality

by adding organic matter and practicing conservation management techniques

Use soil tests to determine whether your soil has the necessary nutrients for good productivity

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HomeworkHomeworkDetermine soil texture at several

locations on your property by the look-and-feel method.

Survey your property for signs of erosion. Can you design solutions?

If you have not done so recently, submit a soil sample to a laboratory. The results will be used in other classes.