LAND JUDGING

Land Classification

The Soil Conservation Service uses a classification system to describe the capability of the soils to produce crops.

SCS CAPABILITY CLASSES

There are 8 SCS land capability classes. Each class is based on what the land may be used for and what is required to maintain the classification

LAND CAPABILITY CLASSES

Class I-Cultivated cropsClass II-Cultivated cropsClass III-Cultivated cropsClass IV-Cultivated cropsClass V-PastureClass VI-PastureClass VII-ForestryClass VIII-Wildlife & Recreation

FACTORS AFFECTING LAND CLASS

• Slope

• Topsoil thickness

• Erosion

• Topsoil texture

• Permeability of subsoil

• Drainage

• Effective depth

SLOPE CATEGORIESfor South Georgia

Range Land Class

Nearly level 0-2% IVery gentle 2-5% IIGentle 5-8% IIISloping 8-12% IVStrongly Sloping 12-17% VISteep >17% VIIVery Steep NA NA

TOPSOIL THICKNESS

Category Range Land Class

Extremely Thick >40” IIIVery Thick 20-40” IThick 10-20” IModerate 5-10” IThin <5” II

Topsoil thickness is measured from the soil surface to the 1st texture change.

EROSION

• The percentage of original topsoil which has eroded.

• Determined by subtracting the actual topsoil from the original and dividing the eroded by the original and multiplying by 100.

EROSION CATEGORIES

Category Range Land Class

None to slight <25% I

Moderate 25-75% II

Severe >75% III

SOIL TEXTURE

Soil is made up of 3 particles: sand, silt & clay

There are 3 categories of texture:Fine-smooth, sticky with no grit, will form a 2 inch or longer ribbonMedium-between fine & coarse, will form a ball and show some finger marks, will form a short ribbonCoarse-sandy, will not form a ribbon

PERMEABILITY OF SUBSOIL

The ability of air & water to move through the subsoil. Based on subsoil texture.

Rapid-coarse texture >20”

Moderate-medium texture subsoil

Slow-fine texture subsoil

DRAINAGE

Refers to surface & internal drainageAs a general rule, the quicker the soil can be

tilled following a good rainfall the better the drainage.

Color is the best indicator of drainageBright colors (reds & yellows) indicate good

drainageDull colors (grays & browns) indicate poor

drainage

DRAINAGE CATEGORIES

Category Looks

Excessively drained Coarse texture for over 40”

Well-drained No gray mottles in top 30”

Moderately well-drained No gray mottles in top 20”

Somewhat poorly drained No gray mottles in top 10”

Poorly drained Gray matrix or gray mottles in top 10”

Very wet Surface water

DRAINAGE LAND CLASS

Category Land Class

Excessively drained III

Well-drained I

Moderately well-drained II

Somewhat poorly drained III

Poorly drained IV

Very Wet V

EFFECTIVE DEPTH

The depth to which plant roots can easily penetrate. Usually the combined thickness of the topsoil and subsoil.

Hard pans and plow pan layers may affect root depth.

The presence of roots is a good indication of effective depth.

EFFECTIVE DEPTH RANGE

Category Range Land Class

Deep Roots over 40” I

Moderate Roots from 20-40” II

Shallow Roots from 10-20” III

Very Shallow Roots <10” IV

LAND TREATMENT PRACTICESVegetative

1. Use conserving & improving crops occasionally-Always on class I

2. Use conserving & improving crops 1/2 of time-Always on class II

3. Use conserving & improving crops 2/3 of time-Always on class III

4. Use conserving & improving crops 3/4 of time-Always on class IV

5. Prevent residue burning-Always on classes I, II, III, & IV

6. Provide mulching with crop residue-Always on classes I, II, III, & IV

7. Use strip crops-On II, III & IV if terraces are not used & D slopes if terraces are used

8. Use crop rotation-Always on classes I, II, III, & IV

9. Control weeds, bushes & trees-Always on classes I, II, III, IV, & VI

10. Establish recommended grass and/or legumes-On pasture if < 50% of the plot is covered by a desirable species

11. Improve present stand of pasture-Always on class VI when practice #10 is not used

12. Control grazing-Always on class VI

13. Fence the pasture-Always on class VI

14. Use artificial reforestation-On class VII with no trees or if stand is poor & seed trees are absent

15. Use natural reforestation-Always on class VII; applies to current & future growth

16. Use prescribed burn occasionally-Always on class VII

17. Protect trees from wildfires-Always on class VII

18. Control forest insects & diseases-Always on class VII

19. Protect trees from animal damage-Always on class VII

20.Control undesirable species-Always on class VII

21.Harvest trees by clear cutting-On VII with a mature stand or if it has merchantable trees of an undesirable species & no merchantable trees of a desirable species

22.Harvest trees by selective cutting-Always on class VII; applies to current or future growth

LAND TREATMENT PRACTICESMechanical

23.Terrace the field-On II, III & IV when slope > 2% & topsoil < 20 inches

24.Maintain field terraces-Always when #23 is used

25.Establish vegetative waterways-Always when #23 is used

26.Construct diversion terraces-On I, II, III, IV & VI if an up-slope water problem exists

27.Plow & cultivate on the contour-Always on cropland & pasture

28.Control existing gullies by special methods-Always on cropland and on pasture when present

LAND TREATMENT PRACTICESPlant Nutrients

29. Apply lime-On I, II, III, IV if pH < 6.0 & on pasture if pH < 6.5

30. Apply manure-On I, II, III, IV & pasture when available

31. Apply nitrogen-Always on classes I, II, III, IV & pasture

32. Apply phosphorus-On I, II, III, IV & VI if phosphorus is less than very high

33. Apply potash-On I, II, III, IV & VI when potash is less than very high