The Land Capability Classification (LCC) system is a framework used by land managers and conservationists to assess land use suitability. Developed by the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS), the LCC groups soils based on their suitability for various agricultural purposes and the risk of soil damage during farming. It provides a standardized method for interpreting soil survey data, helping determine the necessary intensity of management and conservation practices for appropriate land use planning across different landscapes.
The Foundational Eight Classes
The Land Capability Classification system is built upon eight distinct classes, designated by Roman numerals I through VIII. These classes represent a progressive scale of increasing limitations for agricultural use. Class I has the fewest restrictions and widest range of uses, while Class VIII denotes land with the most severe limitations.
Classes I through IV are generally considered suitable for cultivation, often referred to as arable land. The level of required management increases across these four classes. Conversely, Classes V through VIII are generally not suitable for tilled cultivation due to permanent hazards. Land in these higher classes is better suited for uses such as pasture, range, forestland, or wildlife habitat.
Detailed Review of Cultivable Land (Classes I-IV)
Land in Class I features deep, well-drained soils that are nearly level or gently sloping, with minimal risk of erosion. These soils have few limitations and require only ordinary management practices, such as maintaining fertility, to sustain high yields. Class II land shows moderate limitations that slightly reduce the range of crops or require simple conservation practices. These limitations might include a gentle slope, a moderate erosion hazard, or a slightly less than ideal soil depth.
Class III soils have severe limitations that restrict the choice of plants and necessitate special conservation practices. Restrictions include steeper slopes, slow water permeability, or a lower capacity to hold moisture. Practices like terracing or strip-cropping are often required to control soil loss. Class IV represents the most marginal cultivable land, possessing very severe limitations that reduce crop choice and demand intensive management. This land may be cultivated only for a few specific crops and often requires long periods of perennial cover crops in rotation.
Detailed Review of Non-Cultivable Land (Classes V-VIII)
Class V land is generally not suitable for cultivation, even though it is typically flat and not subject to an erosion hazard. The limitations are usually impractical to remove, such as frequent wetness due to a high water table or an abundance of stones. This land is best utilized for uses that do not require regular tilling, such as managed pasture or commercial forestry.
Land in Class VI and Class VII faces severe and permanent limitations that make it unsuitable for regular cultivation. Class VI soils have limitations like steep slopes, severe erosion risk, or very shallow soil depth, restricting their use mainly to grazing or woodland. Class VII soils face very severe limitations, such as extremely shallow rooting zones or intense erosion hazards, and are best reserved for range or wildlife habitat.
The final category, Class VIII, includes land with limitations so severe that it precludes commercial plant production. This classification includes areas like barren lands, high mountain terrain, permanent swamps, or extremely rocky outcrops. Class VIII land is typically reserved for non-agricultural purposes, such as watershed protection, recreation, or specialized wildlife preservation.
Refining the System with Subclasses
The Land Capability Classification system adds a secondary layer of detail using subclasses, which are denoted by a lowercase letter appended to the Roman numeral class (e.g., IIe or IIIw). These subclasses identify the dominant type of limitation or hazard affecting the soil, providing land managers with specific information about the nature of the conservation problem.
There are four primary subclasses recognized within the system:
- The ‘e’ subclass signifies that the primary limitation is a risk of erosion, often related to the land’s slope.
- The ‘w’ subclass indicates that the limitation is due to excess water, such as poor drainage, a high water table, or frequent overflow.
- The ‘s’ subclass denotes limitations related to the soil itself or the rooting zone, including issues like shallow soil depth, stoniness, or a low moisture-holding capacity.
- The ‘c’ subclass is used to indicate a climate limitation, often applied in areas where the growing season is restricted by cold temperatures or a lack of moisture.
This level of detail allows for targeted conservation planning.