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Documentation

Background

Irrigation is critical to agriculture in the United States: nearly 55 percent of the value of all crops sold comes from irrigated farms accounting for only 30 percent of all harvested cropland (USDA/NASS, 2007 Census of Agriculture). In the process, agriculture accounts for over 80 percent of water consumed (i.e., withdrawn from surface- or groundwater sources and lost to the immediate water environment through evaporation, plant transpiration, incorporation in products or crops, or consumption by humans or livestock).

Irrigation is particularly important for agriculture in the Western United States, where irrigated farms accounted for 60 percent of all crop sales in 2008, and 75 percent of U.S. irrigated cropland acres. Farms in the 17 Western States use a wide variety of irrigation systems, about 36 percent of irrigated acres are irrigated with gravity-based systems (e.g., gated-pipe furrow systems or flooding entire fields) and 67 percent are irrigated with pressure-sprinkler systems (e.g., center-pivot sprinkler or drip/trickle systems). (Some acres are irrigated with both system types.) To improve irrigation efficiency, Federal and State agencies and local water management districts have provided financial and technical assistance to producers to improve water delivery on farms (such as the lining of open-ditch irrigation systems) and/or promote more efficient application technologies (such as low-pressure sprinkler irrigation systems). About 18 percent of irrigated farms in the West participated in these programs during 2003-08.

Most irrigated farms in the West are small farms (under $250,000 in annual sales), as are most farms that receive financial assistance to improve irrigation efficiency. But larger farms ($250,000 or more in annual sales) use the most irrigation water, and the largest 15 percent of irrigated farms ($500,000 or more in annual sales) account for 66 percent of total farm water applied in the West. Farm-size classes are defined to be consistent with the ERS farm typology (see Structure and Finances of U.S. Farms: Family Farm Report, 2010) in place when the source data were collected. ERS has since revised its typology (see Updating the ERS Farm Typology, EIB-110, April 2013). Financial and technical assistance programs that target larger farms more heavily may conserve more water and better meet environmental and other policy objectives. For more details, see the Summary of Results.

Data Source and Scope

Data in the 158 tables highlight the structural characteristics of western irrigated agriculture across four farm-size classes based on data from USDA's 2008 Farm and Ranch Irrigation Survey (FRIS). Where available, the tables also have tabs with similar data from the 1998 FRIS.

Structural characteristics were summarized only for irrigated agriculture within the 17 contiguous Western States for several reasons. First, these States dominate irrigated agriculture in terms of the number of irrigated farms, as well as the extent of irrigated acreage, water use, and value of irrigated farm sales. Second, much of irrigated agriculture in the 31 Eastern States (while economically important regionally) occurs largely as supplemental irrigation, while in many parts of the West, crop production may not be an option without irrigation. In addition, while water reallocation can be a contentious issue across the U.S., it is especially so in the more arid western States.

The four farm-size classes used for this analysis were defined using "total farm sales" from the 2007 Census of Agriculture, carried over to FRIS (by observation). Farm-size classes are defined to be consistent with the ERS farm typology (see Structure and Finances of U.S. Farms: Family Farm Report, 2010) in place when the data were collected. ERS has since revised its typology (see Updating the ERS Farm Typology, EIB-110, April 2013).

Farm-Size Class Definitions Used to Examine Structural Characteristics of Irrigated Agriculture
Farm-size class (1 through 4) 1 based on total farm sales Corresponding ERS farm typology definition2
1 = Small ($0 to $99,000) Includes ERS's retirement, residential/lifestyle, and lower sales/farming occupation groups
2 = Medium ($100,000 to $249,999) Medium sales, farming-occupation group
3 = Large ($250,000 to $499,999) Large family farm group
4 = Largest ($500,000 and greater) Very large family farm group
1/ Farm-size classes were defined using the value of the total farm sales variable from the 2007 Census of Agriculture applied to the 2008 FRIS data (by observation).

2/ Nonfamily corporate farms could not be identified with FRIS data. For more information on the ERS farm typology, see Structure and Finances of U.S. Farms: Family Farm Report, 2010.

Methodology, Data Reliability, and Measures of Accuracy

Sampled observations for FRIS were selected from irrigated farms and ranches identified in the 2007 Census of Agriculture (23,089 farm operations across all 50 States, with 6,769 farm operations from the 17 Western States). For a detailed explanation of FRIS sample design characteristics, coverage, statistical methodology, estimation, response rates, and reliability measures, see Appendices A and B for FRIS on the NASS website: http://www.agcensus.usda.gov/Publications/2007/Online_Highlights/Farm_and_Ranch_Irrigation_Survey/index.php.

For this analysis, three additional data reliability issues deserve some attention. First, for each of the summary data tables, a cell value of "d" indicates "insufficient data for publication." Consistent with USDA/NASS data disclosure requirements for FRIS, summarized data could be published only if the summary statistic was based on five or more represented farms. For most summary tables, the FRIS sample size was more than sufficient across farm-size classes by State to meet this test. Disclosure "d" appears across farm-size classes for only a few summary tables, namely those tables summarizing a statistic for a subtopic area, like pumping (energy) costs by farm-size class for farms using gasoline rather than electricity to power well pumps.

Second, for such key variables as the number of irrigated farms, acres irrigated, and water applied (total and by water source), values by State for the "total" column in the appropriate summary tables are equivalent to values reported in the FRIS report for corresponding State-level summary tables. Thus, the summarized data tables present a farm-size "structural" view of irrigation characteristics reported in the FRIS report.

Third, for all data tables summarizing a weighted-average statistic, coefficient of variation (CV) statistics were computed by farm-size class and by State (and region). Coefficient of variation values were computed as [(standard error of the estimate divided by the estimate) x 100], and reported in the appropriate data tables using * for CV < 25; ** for 25 < CV < 50; *** for 50 < CV < 100; and **** for CV > 100. For most summary tables, CV values across farm-size classes across the Western States were generally less than 25 and most often less than 50, indicating relatively low variability of irrigation characteristics within most farm-size classes.

2008 FRIS Irrigated Farm Numbers by Farm-Size Class, 17 Western States
  Farm-size class (1 – 4) Total
FRIS sample results: 1=small 2=medium 3=large 4=largest All farm-size classes
Actual FRIS farm observations 1,201 908 1,081 3,579 6,769
NASS expanded (represented) farms 97,667 20,260 14,026 23,893 155,846

Reference Date

This document was prepared on June 7, 2013.

Last updated: Friday, June 07, 2013

For more information contact: Glenn Schaible

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