USDA-NASS Cropland Data Layer Illinois 1999-2006 | clearinghouse.isgs.illinois.edu

Data

Summary

The United States Department of Agriculture, National Agricultural Statistics Service (USDA-NASS) Cropland Data Layer (CDL) for Illinois is a raster, geo-referenced, categorized land cover data layer. Between 1999-2005 this data layer was produced annually using satellite imagery from the Thematic Mapper (TM) instrument on Landsat 5 and the Enhanced Thematic Mapper (ETM+) on Landsat 7. The ground resolution is 30 meters by 30 meters. Beginning in 2006, the CDL data layer uses the satellite imagery from the Indian Remote Sensing RESOURCESAT-1 Advanced Wide Field Sensor (AWiFS), which has a ground resolution of 56 x 56 meters. The Illinois Cropland Data Layer is aggregated to 13 standardized categories for display purposes with the emphasis being agricultural land cover. No individual farmer's reported data is included or derivable from the Cropland Data Layer.

The NASS Cropland Data Layer(link is external) for Illinois is part of a series in which several states are categorized annually based on the extensive field observations collected during the annual NASS June Agricultural Survey. This is a national survey based on a stratified random sample of land areas selected from each state's area frame. An area frame is a land use stratification based on percent cultivation. Our field enumerators are given questionnaires to ask farmers what, where, when and how much they are planting. Our surveys focus on cropland, but the enumerators record all land covers within the sampled area of land whether it is cropland or not. NASS uses broad land use categories to define land that is not under cultivation, including; non-agricultural, pasture/rangeland, waste, woods, and farmstead.

Data

Purpose

The purpose of the Illinois Cropland Data Layer Program is to use satellite imagery on an annual basis to provide supplemental acreage estimates for the state's major commodities ,and to produce digital, crop specific, categorized geo-referenced output products. These data are intended for geographic display and analysis at the state level. The cropland data layers are provided "as is". USDA-NASS does not warrant results you may obtain using the data.

Copyright Restrictions

There are NO copyright restrictions with the NASS Cropland Data Layer imagery. The categorized imagery is considered public domain and free to redistribute. However, NASS would appreciate acknowledgment or credit for the usage of our categorized imagery.

Attributes

The following is a cross-reference list of the categorization codes and land covers used in all states involved in the Cropland Data Layer Program. Not all land cover categories listed below will appear in an individual state; the Illinois Cropland Data Layer uses 13 of these categories.

Attribute Domain Values and Definitions ROW CROPS 1-20
Categorization Code	Land Cover
1	Corn
2	Cotton
3	Rice
4	Sorghum
5	Soybeans
6	Sunflowers
10	Peanuts
11	Tobacco
Attribute Domain Values and Definitions SMALL GRAINS & HAY 21-40
Categorization Code	Land Cover
21	Barley
22	Durum Wheat
23	Spring Wheat
24	Winter Wheat (AR,IL,MS,NM)
25	Other Small Grains & Hay (Oats, Millet, Rye & Winter Wheat, Alfalfa & Other Hay)
26	Winter Wheat/Soybeans Double Cropped
Attribute Domain Values and Definitions OTHER CROPS 41-60
Categorization Code	Land Cover
41	Beets
42	Dry Edible Beans
43	Potatoes
44	Other Crops (Canola, Flaxseed, Safflower & very small acreage crops)
50	State 560 CRP
51	State 561 Popcorn
52	State 562 Snap Beans
53	State 563 Green Peas
54	State 564 Pumpkins
55	State 565 Apples
56	State 566 Peaches
57	State 567 Sweet Corn - fresh
58	State 568 Sweet Corn - processing
59	State 569 Other Crops
Attribute Domain Values and Definitions OTHER LAND 61-80
Categorization Code	Land Cover
61	Fallow/Idle Cropland
62	Pasture/Range/CRP/Non Ag (Permanent & Cropland Pasture, Waste & Farmstead)
63	Woods
Attribute Domain Values and Definitions OTHER 81-99
Categorization Code	Land Cover
81	Clouds
82	Urban
83	Water
84	Roads/Railroads
85	Ditches/Waterways
86	Buildings/Homes/Subdivisions
87	Wetlands
88	Grassland
90	Mixed Water/Crops
91	Mixed Water/Clouds

Classification accuracy is generally between 85% to 95% correct for agricultural-related land cover categories. Detailed classification statistics are available on the official NASS Cropland Data Layer CD-ROM(link is external).

The categorized images are co-registered to ortho-rectified GeoCover Stock Mosaic images using automated block correlation techniques. The GeoCover Stock Mosaics are within 50 meters root mean squared error overall.