As part of its effort to assess land cover across the agricultural areas in the United States, the U.S. Department of Agriculture (USDA) has established the Common Land Unit (CLU) as a standardized GIS data layer.
The USDA defines a CLU as:
the smallest unit of land that has a permanent, contiguous boundary, a common land cover and land management, a common owner and a common producer association. (www.fsa.usda.gov/FSA/apfoap p?area=home&subject=prod&topic=clu-ab)
This layer includes all farm fields, managed forested tracks, and other managed areas. CLU data is often used with other GIS layers to support a variety of applications including: public safety and disaster response, agriculture and natural resource management and monitoring, regional planning, economic development, and natural disaster planning and mitigation.
CLU is a vector file. The illustration provided in the CLU section on the supplemental metadata file shows CLU boundaries (left) and CLU boundaries superimposed over aerial photography (right). Note: Most of the attribution (descriptive information) associated with the CLU boundaries on this file has been deleted by the FSA to protect individual privacy. Attributes that are available to the public include field size in acres.
Data Type: Vector / Polygon
Attribution: CalcAcres: Area in acres / polygon
-Universal Trans Mercator
-Zone: 17 or 18 (Contingent on locality, refer to UTM map in the Appendix)
-Spheroid: NAD 83
Source: Farm Service Agency through the Natural Resource Conservation Service (NRCS) Geospatial data Gateway