U.S. DEPARTMENT OF AGRICULTURE NATURAL RESOURCES CONSERVATION SERVICE 04/27/2000 PRIME FARMLAND SOILS Napa County, California: Detailed Soil Map Legend (Urban or built-up areas within the map units listed below are not considered Prime Farmland.) __________________________________________________________________________________________________________________ | | | | Map | Map Unit name | |symbol | | |_______|_________________________________________________________________________________________________________| | | | |103 |BALE LOAM, 0 TO 2 PERCENT SLOPES (Prime farmland if irrigated) | |104 |BALE CLAY LOAM, 0 TO 2 PERCENT SLOPES (Prime farmland if irrigated) | |105 |BALE CLAY LOAM, 2 TO 5 PERCENT SLOPES (Prime farmland if irrigated) | |116 |CLEAR LAKE CLAY, DRAINED (Prime farmland if irrigated) | |117 |CLEAR LAKE CLAY, OVERWASHED (Prime farmland if irrigated) | |118 |COLE SILT LOAM, 0 TO 2 PERCENT SLOPES (Prime farmland if irrigated) | |119 |COLE SILT LOAM, 2 TO 5 PERCENT SLOPES (Prime farmland if irrigated) | |122 |COOMBS GRAVELLY LOAM, 0 TO 2 PERCENT SLOPES (Prime farmland if irrigated) | |123 |COOMBS GRAVELLY LOAM, 2 TO 5 PERCENT SLOPES (Prime farmland if irrigated) | |126 |DIABLO CLAY, 5 TO 9 PERCENT SLOPES (Prime farmland if irrigated) | | | Soils on slopes greater than 8 percent are not considered prime for this map unit. | |161 |MAXWELL CLAY, 2 TO 9 PERCENT SLOPES (Prime farmland if irrigated) | | | Soils on slopes greater than 7 percent are not considered prime for this map unit | |168 |PERKINS GRAVELLY LOAM, 2 TO 5 PERCENT SLOPES (Prime farmland if irrigated) | |169 |PERKINS GRAVELLY LOAM, 5 TO 9 PERCENT SLOPES (Prime farmland if irrigated) | | | Soils on slopes greater than 7 percent are not considered prime for this map unit. | |170 |PLEASANTON LOAM, 0 TO 2 PERCENT SLOPES (Prime farmland if irrigated) | |171 |PLEASANTON LOAM, 2 TO 5 PERCENT SLOPES (Prime farmland if irrigated) | |180 |TEHAMA SILT LOAM, 0 TO 5 PERCENT SLOPES (Prime farmland if irrigated) | |181 |YOLO LOAM, 0 TO 2 PERCENT SLOPES (Prime farmland if irrigated) | |182 |YOLO LOAM, 2 TO 5 PERCENT SLOPES (Prime farmland if irrigated) | |_______|_________________________________________________________________________________________________________| Prime Farmland Prime farmland is one of several kinds of important farmland defined by the U.S. Department of Agriculture. It is of major importance in meeting the Nation's short- and long-range needs for food and fiber. Because the supply of high-quality farmland is limited, the U.S. Department of Agriculture recognizes that responsible levels of government, as well as individuals, should encourage and facilitate the wise use of our Nation's prime farmland. Prime farmland, as defined by the U.S. Department of Agriculture, is land that has the best combination of physical and chemical characteristics for producing food, feed, forage, fiber, and oilseed crops and is available for these uses. It could be cultivated land, pastureland, forestland, or other land, but it is not urban or built-up land or water areas. The soil qualities, growing season, and moisture supply are those needed for the soil to economically produce sustained high yields of crops when proper management, including water management, and acceptable farming methods are applied. In general, prime farmland has an adequate and dependable supply of moisture from precipitation or irrigation, a favorable temperature and growing season, acceptable acidity or alkalinity, an acceptable salt and sodium content, and few or no rocks. It is permeable to water and air. It is not excessively erodible or saturated with water for long periods, and it either is not frequently flooded during the growing season or is protected from flooding. Slope ranges mainly from 0 to 6 percent. More detailed information about the criteria for prime farmland is available at the local office of the Natural Resources Conservation Service. A recent trend in land use in some parts of the survey area has been the loss of some prime farmland to industrial and urban uses. The loss of prime farmland to other uses puts pressure on marginal lands, which generally are more erodible, droughty, and less productive and cannot be easily cultivated. The map units in the survey area that are considered prime farmland are listed in this table. This list does not constitute a recommendation for a particular land use. On some soils included in the list, measures that overcome a hazard or limitation, such as flooding, wetness, and droughtiness, are needed. Onsite evaluation is needed to determine whether or not the hazard or limitation has been overcome by corrective measures. The extent of each listed map unit is shown in table A. The location is shown on the detailed soil maps. The soil qualities that affect use and management are described under the heading "Detailed Soil Map Units."