Land Evaluation and Classification Kevin Jump Bleckley County High School Compiled from the Land Judging Contest Guide originally prepared by Dr. Frank Flanders

Land Capability Classes  There are eight land capability classes. Each class has the same meaning in all parts of the United States. A description of the eight land capability classes and their most intensive use are in the following slides.

Class I  Soils in Class I have very few limitations which restrict their use. They may be used for the production of cultivated crops.

Class II  These soils may also be used for cultivated crops but they have some limitations that require moderate conservation practices.

Class III  Class III land has severe limitations that require special conservation practices and may reduce the choice of crops.

Class IV  These soils are used for cultivated crops but have very severe limitations that restrict the choice of plants and require special management.

Class V  These soils usually appear in small and nearly level drainage ways. They are not subject to erosion but have limitations such as frequent flooding and wetness which make them unfit for cultivation. Class V is used for pasture.

Class VI  These soils have such severe limitations that they are unsuited to cultivated crops and are restricted to pasture, woodland, or wildlife feed and cover.

Class VII  These soils have very severe limitations and their use is restricted to forestry and wildlife.

Class VIII  This soil is so severely limited that its use is devoted entirely to wildlife, water supply, recreation or aesthetic purposes.

Factors Affecting Land Class  Slope  Topsoil Thickness  Erosion  Topsoil Texture  Permeability of Subsoil  Drainage  Effective Depth

Slope  Steepness of the field  Rise over run  Determined by the amount of fall in feet per 100 feet  Expressed in percent

Slope Categories CategoriesSouth GeorgiaN Georgia 1. Nearly Level0 – 2%0 – 2% 2. Very Gentle2 – 5%2 – 6% 3. Gentle5 – 8%6 – 10% 4. Sloping8 – 12%10 – 15% 5. Strongly Sloping12 – 17%15 – 25% 6. SteepOver 17%25 – 60% 7. Very SteepN/AOver 60%

Slope – Best Land Class 1. Nearly LevelI 2. Very GentlyII 3. GentleIII 4. SlopingIV 5. Strongly SlopingVI 6. SteepVII 7. Very SteepVII

Topsoil Thickness  Surface layer of land  Determined by depth to texture change  Topsoil usually darker  Color can indicate the dividing line but not always

Topsoil Thickness Categories 1. Extremely Thickover 40 inches 2. Very Thick20 to 40 inches 3. Thick10 to 20 inches 4. Moderate5 to 10 inches 5. Thinless than 5 inches

Topsoil Thickness – Best Land Class 1. Extremely Thick III 2. Very ThickI 3. ThickI 4. Moderately ThickI 5. ThinII

Erosion  Percent of original topsoil which has eroded  At the CDE the original topsoil thickness will be listed on the assumption card  Calculate by dividing the amount of topsoil that has eroded by the original topsoil thickness

Erosion Categories  None to Slightless than 25% eroded  Moderate25 to 75% eroded  Severeover 75% eroded

Erosion – Best Land Class 1. None to SlightI 2. ModerateII 3. SevereIII

Topsoil Texture  Determined by soil particle size in the topsoil  Sand is the largest  Clay is the smallest  Determined by feel using water

Soil Texture Triangle

Topsoil Texture Categories  Finesmooth and sticky when wet – like flour  Mediummixture of sand, silt and clay – like salt and flour  Coarsemostly sand particles – like salt

Topsoil Texture – Best Land Class 1. FineI 2. MediumI 3. CoarseI

Permeability of Subsoil  Ability of air and water to move through the subsoil  Primarily due to soil texture  Based on texture except when topsoil exceeds 20 inches  When the topsoil depth exceeds 20 inches the subsoil permeability plays a minor role in crop production  In these cases permeability will be based on the texture of the top 20 inches

Subsoil Permeability Categories 1. RapidCoarse texture 2. Moderatemedium texture 3. Slowfine texture

Permeability of Subsoil – Best Land Class 1. RapidII 2. ModerateI 3. SlowII

Drainage  Refers to surface and internal drainage (water movement)  Best clue is color which is determined mostly by iron compounds  Well drained – rusty  Poorly drained - gray

Drainage Categories 1. Excessively drained – coarse textured, sandy material that continues to depths of more than 40 inches 2. Well drained – No gray mottles in top 30 inches 3. Moderately well drained – no gray mottles in top 20 inches 4. Somewhat poorly drained – no gray mottles in top 10 inches

Drainage Categories (cont.) 5. Poorly drained – Gray matrix or gray mottles found in top 10 inches 6. Very Wet – surface water remains for extended periods

Drainage – Best Land Class 1. Excessively drainedIII 2. Well drainedI 3. Moderately well drainedII 4. Somewhat poorly drainedIII 5. Poorly drainedIV 6. WetV

Effective Depth  Depth to which plant roots can easily penetrate and absorb water and nutrients  Usually the combined thickness of topsoil and subsoil  Root penetration may be restricted by rock layers, hardpans and plow pan layers

Effective Depth Categories 1. Deepover 40 inches 2. Moderate20 to 40 inches 3. Shallow10 to 20 inches 4. Very ShallowLess than 10 inches

Effective Depth – Best Land Class 1. DeepI 2. ModerateII 3. ShallowIII 4. Very ShallowIV