Soils and FFA Soils and FFA Land JudgingLand Judging

Jim LathemGeorgia Agricultural Education Curriculum Office

Georgia Department of EducationJuly 2005

This presentation was prepared by the Natural Resource Conservation This presentation was prepared by the Natural Resource Conservation Service in Athens, Georgia – 2005.Service in Athens, Georgia – 2005.

Much of the information in this presentation was extracted from the Much of the information in this presentation was extracted from the “LAND JUDGING CONTEST GUIDE” , A Guide To the Georgia FFA “LAND JUDGING CONTEST GUIDE” , A Guide To the Georgia FFA Land Judging Contest (Flanders, rev. July 2004)Land Judging Contest (Flanders, rev. July 2004)

This presentation is intended to be used as a supplement to the FFA This presentation is intended to be used as a supplement to the FFA

Land Judging Contest Guide. It contains photographs and additional Land Judging Contest Guide. It contains photographs and additional information to assist in the preparation of Georgia FFA Land Judging information to assist in the preparation of Georgia FFA Land Judging Teams on a local basis.Teams on a local basis.

(Instructors should (Instructors should VIEWVIEW the the NOTES PAGENOTES PAGE for instructional information) for instructional information)

Credits

Definition of SoilDefinition of Soil

The unconsolidated mineral or organic The unconsolidated mineral or organic material on the immediate surface of the material on the immediate surface of the earth that serves as a natural medium for earth that serves as a natural medium for the growth of land plants. the growth of land plants.

(Glossary of Soil Science Terms - Soil Science Society of America - Part 1 definition of soil)

Soil FormationSoil Formation

Soils are the product of the effects of climate, topography, and living organisms acting on parent material over a period of time.

Soil Formation - Parent MaterialSoil Formation - Parent Material Parent Material is the “base” material that a soil is formed from.Parent Material is the “base” material that a soil is formed from.

PIEDMONT

FLATWOODS

BLUE RIDGERIDGE & VALLEY

SAND HILL

COASTAL PLAIN

Soils and MLRA

Land Capability ClassificationLand Capability Classification

FACTORS AFFECTING LAND CLASSFACTORS AFFECTING LAND CLASS

Several characteristics of the site must be examined Several characteristics of the site must be examined before determining the land capability class. Each one before determining the land capability class. Each one must be evaluated individually and collectively to must be evaluated individually and collectively to determine the land class. Soil factors to be considered determine the land class. Soil factors to be considered are:are:

Topsoil thicknessTopsoil thickness ErosionErosion Topsoil textureTopsoil texture Permeability of the subsoilPermeability of the subsoil DrainageDrainage Effective depth Effective depth

Each of these characteristics is determined from Each of these characteristics is determined from examining the soil profile. examining the soil profile.

Topsoil ThicknessTopsoil Thickness

South GANorth GA

topsoil

subsoil

In general, topsoil thickness is measured to texture change -- the subsoil or clay layer.

South GA

Soil ErosionSoil Erosion

Erosion is expressed as the percentage of original topsoil which has eroded. At the contest, the original topsoil thickness will be listed on the assumption card. Calculate erosion by dividing the amount of topsoil that has eroded by the original topsoil thickness.

Erosion Categories:1. None to slight - less than 25% eroded2. Moderate - 25 to 75% eroded3. Severe - Over 75% eroded

Soil Erosion is a serious problem that can threaten the productivity of land and can choke streams with sediment. Erosion can be reduced in most cases with the implementation of recommended conservation practices.

Topsoil Texture - Topsoil Texture - Relative Sizes of Relative Sizes of

Soil ParticlesSoil Particles

Sand (0.05-2.00 mm)

Silt (0.002-0.05 mm)

Clay (<0.002 mm)

Soil texture refers to the proportionate content of sand, silt, and clay fractions

Soil Soil TextureTexture

Fine

Medium

Coarse

Soil Textural ClassesSoil Textural Classes

Fine - A fine textured soil is smooth and sticky when wet. The particles feel as fine as flour. When balled in the palm of your hand, it holds its shape and shows finger marks. A long ribbon of soil can be formed by rubbing the soil between the thumb and fore finger.

Medium - A medium textured soil is a mixture of sand, silt and clay particles. It is between fine and coarse. The ball will show some finger marks and hold its shape. A short thick ribbon can be formed.

Coarse - Coarse textured soils are made up of mostly sand particles. Sand feels gritty and particles are large enough to be easily seen. The ball breaks in your hand and almost no ribbon can be formed.

Permeability of the SubsoilPermeability of the Subsoil

Permeability is the ability of the subsoil to transmit air and water.

Permeability may vary within layers of the subsoil. Students should estimate permeability based on the subsoil sample provided.

Permeability is based primarily on the texture and structure of the subsoil (except when the topsoil exceeds 20 inches)

Fine textured soils would always be slow in permeability EXCEPT for the characteristic of structure. Structure refers to the way soil particles clump together in groups (aggregates). The pore spaces between aggregates are large and allow water and air to pass through readily. This means that a fine textured soil may be moderate in permeability.

Soil Structure and PermeabilitySoil Structure and Permeability

Topsoil

Subsoil

Substratum

PermeabilityPermeability

Nut-like structure

Low-porosityPorous

Porous

Permeability of the SubsoilPermeability of the Subsoil

Permeability classesPermeability classes

1.1. RapidRapid -- Due to a coarse texture greater than 20 -- Due to a coarse texture greater than 20 inches.inches.

2.2. ModerateModerate -- Subsoils of fine or medium texture; -- Subsoils of fine or medium texture; well defined nut-like structure*well defined nut-like structure*; ; visible poresvisible pores of of varying size.varying size.

3.3. SlowSlow -- Subsoils of fine texture; sticky or plastic -- Subsoils of fine texture; sticky or plastic clay subsoils; few or no pores visible.clay subsoils; few or no pores visible.

Soil DrainageSoil DrainageDrainage refers to surface

and internal drainage

The best clue to soil drainage is color. The color of most subsoils is determined

by iron compounds. When soils are well aerated, the iron

compounds are in an oxidized form, giving the subsoil a red or yellow color. (Iron oxide is "rust".)

In a poorly aerated soil, the iron compounds will be in a reduced state, giving the soil a gray color.

The soil may have a general gray color or be mottled (blotchy, spotted) with gray. Mottled colors of gray, yellow, and brown frequently appear. Soil mottling generally corresponds to the depth of the seasonal water table.

Gray color

Oxidized color

Mottled with gray color

Soil DrainageSoil Drainage

Well drained soils -- No mottling or gray soil colors

Soil DrainageSoil Drainage

Gray colors (with or without mottles)indicate wetness

Soil Drainage ClassesSoil Drainage Classes

1.1. Excessively drainedExcessively drained -- Coarse textured, sandy material that -- Coarse textured, sandy material that continues to depths of more than 40 inches.continues to depths of more than 40 inches.

2.2. Well-drainedWell-drained -- No gray mottles found in top 30 inches of profile. -- No gray mottles found in top 30 inches of profile.

3.3. Moderately well-drainedModerately well-drained -- No gray mottles found in top 20 inches -- No gray mottles found in top 20 inches of profile.of profile.

4.4. Somewhat poorly drainedSomewhat poorly drained -- No gray mottles found in top 10 -- No gray mottles found in top 10 inches of profile.inches of profile.

5.5. Poorly drainedPoorly drained -- Gray matrix or gray mottles found in top 10 -- Gray matrix or gray mottles found in top 10 inches of profile. Soil may be gray completely to the surface.inches of profile. Soil may be gray completely to the surface.

6.6. Very wetVery wet -- Surface water remains for extended periods. -- Surface water remains for extended periods.

Effective DepthEffective Depth

Effective Depth is that depth to which plant roots can easily penetrate. It is usually the combined thickness of the topsoil and subsoil -- measured to the parent material, although an area of non-restrictive parent material may also be included in the effective depth. However, root penetration may be restricted by rock layers, hardpans and plow pan layers. A good indication of the effective depth is the presence of roots.

Effective Depth Classes

1. Deep -- Over 40 inches2. Moderate -- 20 to 40 inches3. Shallow -- 10 to 20 inches4. Very Shallow -- Less than 10 inches

Effective DepthEffective Depth

Deep effective depth

Root penetration stopped by weathered rock

Root penetration stopped by hard rock

Effective DepthEffective Depth

Root penetration stoppedby platy soil structure

Root penetration stoppedby parent material

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and

activities on the basis of race, color, national origin, sex, religion, age, disability, political beliefs, sexual

orientation, and marital or family status. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille,

large print, audiotape, etc.) should contact USDA's TARGET Center at 202-720-2600 (voice and TDD).To file a complaint of discrimination write USDA,

Director, Office of Civil Rights, Room 326-W, Whitten Building, 14th and Independence Avenue, SW, Washington, DC 20250-9410 or call 202-720-

5964 (voice or TDD). USDA is an equal opportunity provider and employer.