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RI Soil Survey - Prime Farmlands

RI Soil Survey - Prime and Important Farmland - November 2013

Link to: Title 7 Definitions

View official Prime/Statewide Important list for RI November 2012 Version
Map of Rhode Island Prime Farmland Soil Loss from 1981 to 2004 (PNG, 497 KB)
 

Introduction

The Natural Resources Conservation Service (NRCS) is committed to the management and maintenance of the resource base that supports the productive capacity of American Agriculture. This management and maintenance includes identifying the location and extent of the most suitable land for producing food, feed, fiber, forage, and oilseed crops. Prime farmland information is supplemented with separate designations of soil map units that have statewide, local, or unique importance as farmland capable of producing these crops.

The USDA - Natural Resources Conservation Service (NRCS) and the Rhode Island Department of Administration's Division of Planning have identified those lands in Rhode Island that have a combination of physical and chemical features that make them best suited for farming. These "Important Farmlands" are subdivided into: 1) "Prime Farmlands" which are the best soils for agricultural use, and 2) "Additional Farmlands of Statewide Importance" which are other soils that are lass well suited for intensive farming but are still valuable for many farm enterprises.

No "Unique" or "locally important" farmlands have been identified in Rhode Island.

To Qualify as an area of Important Farmland, the land must be available for agricultural use, but need not currently be farmed. The term "available" means the land must not have been physically converted to a land use that makes in impossible to farm in the future, such as a residential subdivision. The availability of the land is not dependent on the owner's intentions or plans, but rather on the physical condition of the land.

(A) Prime Farmlands

(1) General: Prime farmland is land that has the best combination of physical and chemical characteristics for producing food, feed, forage, fiber, and oilseed crops, and is also available for these uses (the land could be cropland, pastureland, range-land, forest land, or other land, but not urban built-up land or water). It has the soil quality, growing season, and moisture supply needed to economically produce sustained high yields of crops when treated and managed, including water management, according to acceptable farming methods. In general, prime farmlands have an adequate and dependable water supply from precipitation or irrigation, a favorable temperature and growing season, acceptable acidity or alkalinity, acceptable salt and sodium content, and few or no rocks. They are permeable to water and air. Prime farmlands are not excessively erodible or saturated with water for a long period of time, and they either do not flood frequently or are protected from flooding. Examples of soils that qualify as prime farmland are Bridgehampton silt loam, 0 to 3 percent slopes; Paxton fine sandy loam, 0 to 3 percent slopes; and Newport silt loam, 3 to 8 percent slopes.

(2) Specific Criteria: Prime farmlands meet all the following criteria. 1. Terms used in this section are defined in USDA publications. "Soil Taxonomy, Agriculture Handbook 436", "Soil Survey Manual, Agriculture Handbook 18", "Rainfall-erosion Losses From Cropland, Agriculture Handbook 282", "Wind Erosion Forces in the United States and Their Use in Predicting Soil Loss, Agriculture Handbook 346"; and "Saline and Alkali Soils, Agriculture Handbook 60."

(i) The soils have:

(a) Aquic, udic, ustic, or xeric moisture regimes and sufficient available water capacity within a depth of 40 inches (1 meter), or in the root zone (root zone is the part of the soil that is penetrated or can be penetrated by plant roots) if the root zone is less than 40 inches deep, to produce the commonly grown cultivated crops (cultivated crops include, but are not limited to, grain, forage, fiber, oilseed, sugar beets, sugarcane, vegetables, tobacco, orchard, vineyard, and bush fruit crops) adapted to the region in 7 or more years out of 10; or,
(b) Xeric or ustic moisture regimes in which the available water capacity is limited, but the area has a developed irrigation water supply that is dependable (a dependable water supply is one in which enough water is available for irrigation in 8 out of 10 years for the crops commonly grown) and of adequate quality; or,
(c) Aridic or torric moisture regimes, and the area has a developed irrigation water supply that is dependable and of adequate quality; and,

(ii) The soils have a temperature regime that is frigid, mesic, thermic, or hyperthermic (pergelic and cryic regimes are excluded) These are soils that, at a depth of 20 inches (50 cm), have a mean annual temperature higher than 32 deg. F (0 deg. C). In addition, the mean summer temperature at this depth in soils with an O horizon is higher than 47 deg. F (8 deg. C); in soils that have no O horizon, the mean summer temperature is higher than 59 deg. F (15 deg. C); and,

(iii) The soils have a pH between 4.5 and 8.4 in all horizons within a depth of 40 inches (1 meter) or in the root zone if the root zone is less than 40 inches deep; and,

(iv) The soils either have no water table or have a water table that is maintained at a sufficient depth during the cropping season to allow cultivated crops common to the area to be grown; and,

(v) The soils can be managed so that, in all horizons within, a depth of 40 inches (1 meter) or in the root zone. If the root zone is less than 40 inches deep, during part of each year the conductivity of the saturation extract is less than 4 mmhos/cm and the exchangeable sodium percentage (ESP) is less than 15; and,

(vi) The soils are not flooded frequently during the growing season (less often than once in 2 years); and,

(vii) The product of K (erodibility factor) x percent slope is less than 2.0, and the product of I (soils erodibility) x C (climatic factor) does not exceed 60; and

(viii) The soils have a permeability rate of at least 0.06 inch (0.15 cm) per hour in the upper 20 inches (50 cm) and the mean annual soil temperature at a depth of 20 inches (50 cm) is less than 59 deg. F (15 deg. C); the permeability rate is not a limiting factor if the mean annual soil temperature is 59 deg. F (15 deg. C) or higher; and,

(ix) Less than 10 percent of the surface layer (upper 6 inches) in these soils consists of rock fragments coarser than 3 inches (7.6 cm).

(B) Additional Farmland of Statewide Importance

This is land, in addition to prime and unique farmland, that is of statewide importance for the production of food, feed, fiber, forage, and oil seed crops. Criteria for defining and delineating this land are to be determined by the appropriate state agency or agencies. Generally, additional farmlands of statewide importance include those that are nearly prime farmland and that economically produce high yields of crops when treated and managed according to acceptable farming methods. Some may produce as high a yield as prime farmlands if conditions are favorable. In some states, additional farmlands of statewide importance may include tracts of land that have been designated for agriculture by state law.

Special note: In Rhode Island, all soils that meet the "Prime Farmland" criteria are also included in the "Additional Farmland of Statewide Importance" category. The inclusion of these soils in the list of Additional Lands of Statewide Importance" by the U.S. Dept. of Agriculture resulted from a May 1985 request by the RI Department of Administration's Division of Planning seeking to have the Prime Farmlands afforded the additional protection given to Farmlands of Statewide Importance.