CLASS I (GREEN COLOR). Soils in class I have very few or no limitations that restrict their use.

This type of land is nearly level and the erosion hazard is low. The soils are deep, well-drained, easily worked, hold water well and are either fairly well supplied with plant nutrients or highly responsive to the application of fertilizers. The soils are not subject to damage because of overflow. The local climate must be favorable for growing many of the common field crops. In irrigated areas, the soils may be in class I, if the limitation of the arid climate has been removed by relatively permanent irrigation works.

These soils need ordinary management practices to maintain productivity. Such practices may include the use of one or more of the following: fertilizers, lime, cover and green-manure crops, conservation of crop residues and crop rotations.

Soils in this class are suited to a wide range of plants, may be used for cultivated crops, pastures, forests, and wildlife, food and cover.

CLASS II (YELLOW COLOR). Soils in class II have some limitations which reduce the choice of plants or require simple conservation practices.

The limitations of soils in class II may result from the effects of one or more of the following factors: (i) a gentle slope, (ii) a slight susceptibility to erosion, (iii) less than ideal soil depth, (iv) occasional damaging overflow, (v) wetness which can be corrected by drainage, but existing permanently as a moderate limitation, (vi) slight to moderate salinity or sodium, easily corrected but likely to recur, and (vii) a slight climatic limitation on soil use and management.

These soils require careful management. The limitations are only a few and the practices are easy to apply.

They may need one or more of the following practices: terracing, strip cropping, contour cultivation, water disposal area, covered with vegetation crop rotation, cover and green-manure crops, stubble mulching, the use of fertilizers, manure and lime. These soils may be used for growing cultivated crops, raising pastures, forests, and for wild-life, food and cover.

CLASS III (RED COLOR). Soils in class III have moderate limitations which reduce the choice of plants or require special conservation practices.

Soils in class III have more restrictions than those in class II and, when used for cultivated crops, the conservation practices are usually more difficult to apply and to maintain.

Limitations of soils in class III may result from the effects of one or more of the following factors: (i) a moderately sloping land, (ii) moderately susceptibility to water or wind erosion, (iii) frequent overflow accompanied with some crop damage, (iv) very slow permeability of the sub-soil, (v) wetness or continuing water-logging after drainage, (vi) shallow soil depth up to the bed-rock, hard-pan or clay-pan which limits the rooting-zone and water storage, (vii) low moisture-holding capacity, (viii) moderate salinity or sodium, and (ix) moderate climatic limitations.

CLASS IV (BLUE COLOR). Soils in class IV have severe limitations that restrict the choice of plants and require careful management.

The restrictions in the use of these soils are greater than those in class III and the choice of plants is more limited. When these soils are cultivated, very careful management is required and the conservation practices are more difficult to apply and to maintain.

The use of these soils for cultivated crops is limited as a result of the effect of one or more of the permanent features, such as (i) steep slopes, (ii) severe susceptibility to water or wind erosion, (iii) severe effect of past erosion, (iv) shallow soil, (v) low moisture-holding capacity, (vi) frequent overflow accompanied with severe crop damage, (vii) excessive wetness or continuing hazard of water-logging after drainage, (viii) severe salinity or sodium, and (ix) moderately adverse climate.

These soils can be used for crops, pastures, forests, and wild-life food and cover.

CLASS V (DARK GREEN OR UNCOLORED). Soils in class V have little or no erosion hazard, but have other limitations, the removal of which is not practicable. They are used largely for pastures, forests, and wild-life food and cover.

Such land is nearly level and is not subject to more than slight wind or water erosion. Cultivation is not feasible because of one or more limitations, such as overflow, stoniness, wetness or severe climate. Examples of class V land are (i) soils of lowlands subject to frequent overflows which prevent the normal production of cultivated crops, (ii) nearly level soils with growing season that prevents the normal production of cultivated crops,(iii) the level or nearly level stony or rocky soils, and (iv) ponded areas where drainage for cultivated crops is not feasible but where soils are suitable for grasses or trees. Soils in class V are not suitable for raising cultivated crops, but are suitable for perennial vegetation (grazing and forestry, with few or no limitation). Pastures can be improved, and benefits from proper management can be expected. Physical conditions of soils are such that it is practicable to apply pasture improvements, if needed, such as seeding, liming, fertilizing, and water control with contour furrows, drainage ditches, diversions of water spreaders.

CLASS VI (ORANGE COLOR). Soils in class VI have severe limitations that make them unsuitable for cultivation and limit their use largely for pastures, or forests, or wild-life food and cover.

Soils in class VI have continuing limitations which cannot be corrected, such as (i) steep slope, (ii) very severe erosion hazard, (iii) very severe effect of past erosion (iv) stoniness, (v) shallow rooting-zone, (vi) excessive wetness or overflow, (vii) low moisture capacity, (viii) salinity or sodium, and (ix) severe climate. Soils in this class are subject to moderate limitations under grazing or forestry use.

CLASS VII (BROWN COLOR). Soils in class VII have very severe limitations that make them unsuitable for cultivation and restrict their use largely to grazing, or forestation, or wild-life food and cover. The soils in this class are subject to severe limitations or hazards under either grazing or forestry use. The physical condition of soils is such that it is not practicable to adopt pasture improvements and water-control practices. Soil restrictions are sever e than those in the case of class VI soils.

CLASS VIII (PURPLE COLOR). Soils and land forms in class VIII have limitations that preclude their use for commercial plant production and restrict their use to recreation, wild-life food and cover or to water-supply, water shed protection or for aesthetic purposes.

Significant return on site benefits from soils and land forms in class VIII cannot be expected from management of crops, grasses or trees, although indirect benefits from wild-life, watershed protection or recreation may be possible.

Limitations which cannot be corrected may result from the effects of one or more of the following factors: (i) erosion or erosion hazard, (ii) severe climate, (iii) wet soil, (iv) stones, (v) low moisture capacity, (vi) salinity or sodium.

Bad lands, rock outcrops, sandy beaches, marshes, deserts, river wash, mine tailings and other nearly barren lands are included in class VIII in order to protect other more valuable soils to control water or for wild-life or for aesthetic reasons.

The land-capability class is indicated on the maps by roman numerals I to VIII or by standard colors or by both.

Land-capability subclass. A land-capability class is determined by the degree of limitations in land use together with the hazards involved. For example, in class III land, we have land suitable for cultivation but subject to moderate hazard of water erosion because of a steep slope or a moderate hazard of wind erosion on smooth land or moderate hazard of water-logging or overflow and a shallow depth to the bed-rock. Each of these kinds of limitations are recognized at the subclass. Four kinds of limitations are recognized at the subclass level.

SUBCLASS (E) EROSION. It is made up of soils where the susceptibility to erosion is the dominant hazard in their use. Susceptibility to erosion and damage due to past erosion are major factors that govern the placing of soils in this class.

SUBCLASS (W) EXCESS WATER. It is made up of soils where excess water is the dominant hazard in their use. Poor soil drainage, wetness, high water-table and overflow are the criteria for determining which soils belong in this subclass.

SUBCLASS (S) SOIL LIMITATIONS WITHIN THE ROOTING ZONE. It includes soils which have such limitations as the shallowness of the rooting-zone, stones, low moisture-holding capacity, low fertility difficult to correct and salinity or alkalinity.

SUBCLASS (C) CLIMATIC LIMITATIONS. It includes soils where the climate (temperature or lack of moisture) is the only major hazard of limitations in their use.

The land-capability subclass is designated by the small letters which follow the land-capability classes. Roman numerals, e.g. IIe, IIIs, IVw capability class I has no subclass. Where two kinds of limitation can be modified or corrected and are essentially equal, the subclasses have the following priority e, w, s, c. where soils have two kinds of limitations, the dominant one is shown first.