Overview Of Classification Methodology for Determining Land Capability For Agriculture

The CLI agriculture product shows the varying potential of a specific area for agricultural production. It indicates the classes and subclasses according to the Soil Capability Classification of Agriculture, which is based on characteristics of the soil as determined by soil surveys. The mineral soils are grouped into 7 classes and 13 subclasses according to the potential of each soil for the production of field crops. Organic soils are not a part of the classification and are shown as a single separate unit (0).

These agricultural capability maps can be used at the regional level for making decisions on land improvement and farm consolidation, for developing land-use plans, and for preparing equitable land assessments.

Some of the important factors on which agricultural classification is based are: 1) The soils will be well managed and cropped, under a largely mechanized system. 2) Land requiring improvements, including clearing, that can be made economically by the farmer, is classed according to its limitations or hazards in use after the improvements have been made. Land requiring improvements beyond the means of the farmer is classed according to its present condition. 3) The following are not considered: distances to marker, kind of roads, location , size of farms, type of ownership, cultural patters, skill or resources of individual operations, and hazard of crop damage by storms. 4) The classification does not include capability of soils for trees, tree fruits, small fruits, ornamental plants, recreation, or wildlife. 5) The classes are based on the intensity, rather than kinds, of their limitations for agriculture. Each class includes many kinds of soil, and many of the soils in any class require unique management and treatment. 6) Land given a capability classification of 6 or 7 will never warrant irrigation since the benefits derived from irrigation would be negligible. For this reason, capability Classes 6 and 7 will always appear in the non-irrigated portion (Classes A to C) of a land unit classification.

You can find out more about the CLI mapping project at geogratis.

Land Capability Class Descriptions for Agriculture

The classes indicate the degree of limitation imposed by the soil in its use for mechanized agriculture. The subclasses indicate the kinds of limitations that individually or in combination with others, are affecting agricultural land use.

Classes

Note: To see a further description of each class, select each class in the following table.

Classes Description
Class 1 Soils in this class have no significant limitations in use for crops.
Class 2 Soils in this class have moderate limitations that restrict the range of crops or require moderate conservation practices.
Class 3 Soils in this class have moderately severe limitations that restrict the range of crops or require special conservation practices.
Class 4 Soils in this class have severe limitations that restrict the range of crops or require special conservation practices.
Class 5 Soils in this class gave very severe limitations that restrict their capability in producing perennial forage crops, and improvement practices are feasible.
Class 6 Soils in this class are capable only of producing perennial forage crops, and improvement practices are not feasible.
Class 7 Soils in this class have no capacity for arable culture or permanent pasture.
Class 0 Organic Soils (not placed in capability classes).

Subclasses

Note: To see a further description of each subclass, select each class in the following table.

Subclasses Description
C Adverse climate
D Undesirable soils structure and/or low permeability
E Erosion
F Low fertility
I Inundation by streams or lakes
M Moisture limitations
N Salinity
P Stoniness
R Consolidated bedrock
S Combination of subclasses
T Topography
W Excess water
X This Subclass is comprised of soils having a limitation resulting from the cumulative effect of two or more adverse characteristics