This table shows the degree and kind of soil limitations that affect irrigation systems. The ratings are both verbal and numerical. Rating class terms indicate the extent to which the soils are limited by all of the soil features that affect these uses. "Not limited" indicates that the soil has features that are very favorable for the specified use. Good performance and very low maintenance can be expected. "Somewhat limited" indicates that the soil has features that are moderately favorable for the specified use. The limitations can be overcome or minimized by special planning, design, or installation. Fair performance and moderate maintenance can be expected. "Very limited" indicates that the soil has one or more features that are unfavorable for the specified use. The limitations generally cannot be overcome without major soil reclamation, special design, or expensive installation procedures. Poor performance and high maintenance can be expected.

     Numerical ratings in the table indicate the severity of individual limitations. The ratings are shown as decimal fractions ranging from 0.01 to 1.00. They indicate gradations between the point at which a soil feature has the greatest negative impact on the use (1.00) and the point at which the soil feature is not a limitation (0.00).

      Irrigation systems are used to provide supplemental water to crops, orchards, vineyards, and vegetables in area where natural precipitation will not support desired production of crops being grown.

      “Irrigation, micro (above ground)” evaluates a soil for irrigation systems that apply water at slow rates and are installed above the soil surface but near the plants or crops being irrigated.  The ratings are for soils in their natural condition and do not consider present land use.

     Above ground (drip) micro-irrigation systems generally apply frequent applications of small quantities of water on the soil surface as drops, tiny streams or miniature spray through emitters or applicators placed along a water delivery line.  Generally, these irrigation systems are very efficient in terms of both water and energy use and are suitable for use in vineyards, orchards, windbreaks, nurseries, and on truck crops and some row crops.

     The soil properties and qualities important in the design and management of drip micro-irrigation systems are depth, wetness or ponding, percolation, and flooding.  The soil properties and qualities that influence installation are depth, flooding, and ponding. The features that affect performance of the system and plant growth are the content of salts, calcium carbonate, or sodium.


      “Irrigation, micro (subsurface drip)” evaluates a soil for irrigation systems that apply water at slow rates to the soil rooting zone and are installed beneath the soil surface.  The ratings are for soils in their natural condition and do not consider present land use.

     Subsurface micro-irrigation systems are irrigation systems that apply low volumes of water below the soil surface as drops, tiny streams, or miniature spray through emitters or applicators placed along a water delivery line.  These irrigation systems are buried and apply water directly and very slowly to the root zone.  Generally, these systems are very efficient in terms of both water and energy use and are suitable for use in windbreaks, vegetables, berries, landscape plantings, vineyards, orchards, and some row crops.

     The soil properties and qualities important in the design and management of subsurface micro-irrigation systems are soil depth, available water capacity, wetness or ponding, percolation rate, pH (soil reaction), erosion potential, and flooding.  The soil properties and qualities that influence installation are soil depth, stoniness, flooding, and ponding.  The features that affect performance of the system and plant growth are available water capacity, shrink-swell potential, pH (soil reaction), and the content (or amount) of salts, calcium carbonate, and sodium.

     Information in this table is intended for land use planning, for evaluating land use alternatives, and for planning site investigations prior to design and construction. The information, however, has limitations. For example, estimates and other data generally apply only to that part of the soil between the surface and a depth of 5 to 7 feet. Because of the map scale, small areas of different soils may be included within the mapped areas of a specific soil.

     The information is not site specific and does not eliminate the need for onsite investigation of the soils or for testing and analysis by personnel experienced in the design and construction of engineering works.

     Government ordinances and regulations that restrict certain land uses or impose specific design criteria were not considered in preparing the information in this table. Local ordinances and regulations should be considered in planning, in site selection, and in design. The irrigation interpretations are not designed or intended to be used in a regulatory manner.