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Net Change in Acreage of Prime Farmland Used as Cropland, 1992-1997

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Description

This dot density map shows the general distribution of areas where there were net gains or losses in acreage of prime farmland used as cropland from 1992 to 1997. Each red dot represents a net loss of 2,000 acres of prime farmland used as cropland. This loss may be due either to loss of prime farmland or to conversion of prime farmland to a non-cropland land use. Each blue dot represents a net gain of 2,000 acres of prime farmland used as cropland. This gain may be either new prime farmland or prime farmland that was previously not used as cropland. Dots were aggregated by and placed randomly within 8-digit hydrologic units. Areas with 95% or more Federal area are shown as gray. Total increase for the nation: 1,675,000 acres Total decrease for the nation: 5,393,700 acres Net decrease: 3,718,700 acres

Cautions for this Product:
Note that either a change in the amount of prime farmland or a change in how prime farmland is used will change the amount of prime farmland that is used as cropland. This map does not show the source of change. This map may not be used to determine site-specific information. Data are not collected on Federal land. Data are not available for Alaska or the Pacific Basin. Data for Puerto Rico and the U.S. Virgin Islands is shown by 6-digit hydrologic unit.



Sources

Source: National Resources Inventory, 1997
Distributor: USDA-NRCS-RIAD
Reliability:
NRI sample data are generally reliable at the 95% confidence interval for state and certain broad substate area analyses. Generally, analyses that aggregate data points by smaller geographic areas and/or more specific criteria result in fewer data points for each aggregation and therefore less reliable estimates. NRI maps reflect national patterns rather than site- specific information.


Layers

Aggregate Layer: Cross of State with 8 Digit Hydrologic Units and Federal Land
Other Layers Displayed: States, Rivers


Definitions

Cropland:
A Land cover/use category that includes areas used for the production of adapted crops for harvest. Two subcategories of cropland are recognized: cultivated and noncultivated. Cultivated cropland comprises land in row crops or close-grown crops and also other cultivated cropland, for example, hayland or pastureland that is in a rotation with row or close-grown crops. Noncultivated cropland includes permanent hayland and horticultural cropland. [NRI-97]

Federal land:
A land ownership class designating land that is owned by the Federal Government. It does not include, for example, trust lands administered by the Bureau of Indian Affairs nor Tennessee Valley Authority (TVA) land. No data are collected for any year that land is in this ownership. [NRI-97]

Hydrologic units:
A hierarchical system developed by the U.S. Geological Survey that divides the United States and the Caribbean into 21 major regions, 222 subregions, 352 accounting units, and further subdivided into 2,150 cataloging units that delineate river basins having drainage areas usually greater than 700 square miles. [USGS]

Prime farmland:
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. It has the soil quality, growing season, and moisture supply needed to produce economically sustained high yields of crops when treated and managed according to acceptable farming methods, including water management. 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.[SSM, USDA Handbook No. 18, October 1993]


Product Information

Product ID: 5563
Production Date: 12/13/00
Product Type: Map


For additional information contact the Resources Inventory and Assessment Division. Please include the Product ID you are inquiring about. nri@wdc.usda.gov or 1400 Independence Avenue SW - P.O. Box 2890 - Washington D.C. 20013. If you use our analysis products, please be aware of our disclaimer.