America's croplands are the envy of the world. They produce enough food, fiber, and other products to feed the United States and export significant amounts around the globe. At the same time, the agricultural landscape is a valued component of the American environment.

This report describes not only the fields on which crops are grown, but also other valued elements of the cropland landscape, such as wetlands, windbreaks, and wildlife. We also make note of additional information needed to better report on croplands' key features.

The information provided here is the most recent available. The U.S. Department of Agriculture (USDA) National Resources Inventory (NRI) will complete work on 1997 data in late 1999. These data will be included in the 2001 report. Data from the 1997 Census of Agriculture are included here.

Croplands cover about 20 percent of all US land, roughly 400 million acres, with the highest concentrations in the central United States. The area devoted to cropland has remained fairly stable over the past half century. About 70 percent of all US cropland is classified by USDA as "prime farmland," meaning it has the growing season, moisture, and soil quality to sustain high yields.

Government programs affect how much cropland is actively used and, in some cases, how it is used. Acreage idled per year ranges from zero to nearly 20 percent of croplands. In 1997, almost 9 percent of these lands were out of production under the Conservation Reserve Program (CRP). On almost 30 percent of croplands, farmers must adopt practices to minimize soil erosion to remain eligible to obtain USDA farm program funding.

Farmers set aside 2 million acres in 1997 in a variety of conservation-oriented buffer areas, including windbreaks, field borders, and grassed areas for runoff management. Ten percent of the Nation's wetlands are on croplands. Wetlands are of significant value to wildlife but also complicate the management of individual fields. Finally, intermixing development with croplands can fundamentally change a region's character. To mitigate that effect, state and local programs purchased agricultural easements, which retain lands in agriculture, on nearly three-quarters of a million acres in 1999.

In 1997, agricultural output was valued at $206 billion, approximately the same as in 1948 (adjusted for inflation). However, the quantity of crops produced was more than twice that of 1948. In both years, the crops were produced with approximately the same overall quantity of measured inputs such as labor, capital, fertilizer, and pesticides, resulting in much higher production per unit input in 1997. However, there were significant changes in the mix of inputs between 1948 and 1997: The amount of labor used per unit of crops produced dropped significantly; fertilizer use doubled, and pesticide use increased more than eightfold.

Recreation is an important use of cropland in some areas, but no comprehensive data exist on the acreage used for recreation or farm income from recreation. Information on recreational uses of cropland will likely remain incomplete in the near future.

Crop production per acre has risen steadily over the past 50 years. The amount of nutrition (calories or protein) produced per acre has likely also risen, but only tentative information was available on changes in crops' nutritional content, and on the feed used to produce meat and milk.

Soil quality is affected by multiple factors. Soil erosion affects cropland productivity and water quality. Cropland with highly erosion-prone conditions declined by more than 28 million acres, from 30 percent of US croplands to 24 percent, between 1982 and 1992, while the amount of cropland with low susceptibility to erosion increased by 31 million acres. Erosion is not measured directly, and additional work is required to reach agreement on a preferred measure for reporting on erosion.

In 1996/1997, four states had undesirable levels of acidity in more than half of all soil samples tested, the same as in 1989/1990. In ten states, the percentage of samples with high acidity increased from 1989/90 to 1996/97. Most states had high levels in fewer than 25 percent of soil samples.

The level of organic matter (carbon), the degree of soil compaction, and the acreage affected by salt are key measures of soil quality, but no consistent national data are available.

Irrigated acreage has risen by 25 percent since 1969, accompanied by a 25 percent drop in water used per acre. Drained cropland increased by nearly 60 percent from 1950 to 1985; later data are not available.

Concentrations of most forms of nitrogen and phosphorous considered to be water pollutants are generally higher in agricultural streams and ground water than streams and groundwater in residential or forest areas. About 5 percent of stream samples and 3 percent of ground water samples from agricultural areas exceeded drinking-water standards for nitrate. In 27 states, the majority of soils tested had phosphorous at high or very high levels in 1996/97, up from 24 states in 1989/90.

Farmers in most counties in the United States apply more nitrogen as fertilizer than is taken up by crops, with excess applications at roughly 37 percent, or 6 billion pounds. In addition, the number of counties producing more phosphorous from animal manure than can be used in local crop production has more than tripled since the 1950s, and such counties are located farther south and west than they were in the past. Both practices provide potential sources of water pollutants.

Samples of fish and stream water from agricultural areas generally have fewer pesticides than do those from urban or mixed-land-use areas, whereas agricultural ground water generally has more. About 45 percent of the shallow ground water and more than 80 percent of the streams and fish sampled in agricultural areas contained at least one pesticide; many samples had more. Note that the presence of a pesticide does not imply that a health-based standard has been exceeded.

Most grassland and upland game birds in the central United States (where agriculture predominates) are considered "apparently secure." In both groups, some species are declining in number and others are increasing. Information on waterfowl will be included in future reports. Although the number of managed bee colonies has declined, no consistent or comprehensive information is available on the status and trends in unmanaged pollinator populations. Future reports will reflect work currently under way on this subject.

No consistent or comprehensive information is available on the losses of crops to pests or diseases. Determining crop losses is difficult because yields are influenced by many factors and many pest problems are difficult to diagnose. Pesticide treatments provide an indirect measure; treatment for weeds is uniformly high in all regions of the United States, whereas treatment for insects, diseases, and nematodes varies greatly by region. Finally, no consistent or comprehensive information is available on pesticide resistance.

The table on the next page provides a listing of the measures presented in greater detail on the following pages. Additional information on each measure is presented in the Technical Notes.