Around the world, agricultural practices have developed as a function of topography, soil type, crop type, annual rainfall, and tradition. This montage of six images from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor on NASA’s Terra satellite shows differences in field geometry and size in different parts of the world.
In Minnesota (first), the very regular grid pattern reflects early nineteenth-century surveying; the size of the fields was determined by the need to have a big enough area to make the use of machinery efficient. Dirt roads separate the fields. In Kansas (second), center-pivot irrigation is responsible for the field pattern. Water is drawn up from a well and fed through a tube attached to metal frames. The metal frames are on wheels, and electric motors roll the frames around in a circle, pivoting around the water source, spraying water as they go. In northwest Germany (third), the small size and random pattern of fields is leftover from the Middle Ages. A village or town appears in the left side of the image.
Near Santa Cruz, Bolivia (fourth), the pie-shape or radial-pattern fields are part of a planned settlement scheme in a rainforest area. At the center of each unit is a small community, which is surrounded by fields. A small buffer of forest separates the settlements from one another. Outside of Bangkok, Thailand (fifth), rice paddies fed by an extensive network of canals that is hundreds of years old appear as small skinny rectangular fields. Some fields appear flooded (deep purple), which is part of the growing cycle of rice plants. And in the woodland-savanna region known as the Cerrado (sixth) in southern Brazil, the cheap cost of land and its flatness have resulted in enormous farms and large field sizes. In the large image, each ASTER scene covers an area of 10.5 by 12 kilometers.
Around the world, agricultural practices have developed as a function of topography, soil type, crop type, annual rainfall, and tradition. This montage of six images from shows differences in field geometry and size in different parts of the world.
Green circles in the desert frequently indicate tracts of agriculture supported by center-pivot irrigation. The Al Khufrah Oasis in southeastern Libya (near the Egyptian border) is one of Libya’s largest agricultural projects, and is an easy-to-recognize landmark for orbiting astronauts aboard the International Space Station. Because only about 2 percent of Libya’s land receives enough rainfall to be cultivated, this project uses fossil water from a large underground aquifer. The Libyan government also has a plan called the Great Man Made River to pump and transport these groundwater reserves to the coast to support Libya’s growing population and industrial development.