Land suitable for agriculture is not evenly distributed throughout the world; it tends to be concentrated in limited areas. In order to be considered good farmland, land must be located at the proper elevation and slope.
Because the soil supplies the mineral nutrients required for plant growth, it must also have the appropriate fertility, texture, and pH. Approximately 64 percent of the world’s land has the proper topography, and about 46 percent has satisfactory soil fertility to grow crops.
Plants require large amounts of water for photosynthesis and access to soil nutrients; therefore, farmland must receive an adequate supply of moisture, either from rainfall or from irrigation water.
About 46 percent of the world’s land has adequate and reliable rainfall. Because plant growth is dramatically affected by temperature, farmland must be located in areas with growing seasons long enough to sustain the crop from planting to harvest.
Approximately 83 percent of the world’s land has favorable temperatures. Plants also require sufficient sunlight and atmospheric carbon dioxide levels to support the photosynthetic process necessary for growth and development. Virtually all the world’s land has adequate sunlight and sufficient carbon dioxide to support plant growth.
Crop production requires the right combination of all these factors, and only about 7 percent of the world’s land currently has the proper combination of these factors to make the production of crops feasible without additional technological advances.
Farmland in the United States
With its temperate climate, the United States devotes considerably more of its land area to agriculture than do many other parts of the world. About 45 percent of the land in the United States is used for various forms of agriculture; however, only about 20 percent of the land is actual cropland.
Of the rest, approximately 4 percent is devoted to woodlands, and the other 21 percent is used for other purposes, such as pastures and grasslands. Of the farmland devoted to crop production, only 14 percent is used at any given time to produce harvestable crops.
|Farmland in the United States|
There are seven major agricultural regions in the United States. The dairy region is located in the North Atlantic states and extends westward past the Great Lakes and along the Pacific Coast. The wheat belt is centered in the central and northern Great Plains and in the Columbia Basin of the Northwest.
The general and self-sufficing regions primarily made up of small, family-owned farms are found mostly in the eastern highlands region, which includes the Appalachian Mountains, a few hundred miles inland from the Atlantic Coast, and the Ozark-Ouachita mountains west of the Mississippi River. The corn and livestock belt is found throughout the Midwestern states.
The range livestock region of the western United States stretches in a band from 500 to 1,000 miles wide and extends from the Canadian border to Mexico. The western specialty-crops area is primarily composed of irrigated land in seventeen western states and produces the vast majority of the nation’s vegetable crops.
The cotton belt, located in the southern states (most notably Georgia, Alabama, and Mississippi), contains more farmers than any other region. While this area has been known historically for its cotton production, many other crops, including tobacco, peanuts, truck crops, and livestock are also produced in the South.
In addition to these major regions, smaller farming areas are located throughout the country. Tobacco is produced throughout Kentucky, Virginia, Tennessee, and North and South Carolina.
Apples and other fruits are grown in a variety of places, including the Middle Atlantic seaboard, around the Great Lakes, and the Pacific Northwest. Potatoes are produced in Maine, Minnesota, Idaho, North Dakota, and California. Citrus is grown in southern Texas, Florida, and California. Sugarcane is cultivated in southern Louisiana and Florida.
Loss of Farmland
Most of this decrease is attributed to a combination of urbanization and poor agricultural methods that have led to loss of topsoil through water and wind erosion. Historically, large tracts of farmland have been located near metropolitan areas. In recent times, these urban centers have grown outward into large suburban areas, and this sprawl has consumed many acres of farmland.
Erosion destroys thousands of acres of farmland every year, and desertification—the conversion of productive rangeland, rain-fed cropland, or irrigated cropland into desertlike land with a resulting drop in agricultural productivity—has reduced productivity on 2 billion acres over the past fifty years.
In many cases, the desertified land is no longer useful as farmland. Steps must be taken to preserve this valuable resource, or it is quite possible that the world will suffer mass food shortages in the future.