Lop Nur

The teal and green rectangular form in this area is a field of salt pans. While the desert in the basin by the salt evaporation pans and lake bed appears mostly flat, many high vertical rows of sand dunes can be observed to the south.

Lop Nur salt pans

The curved indentation towards the center of this image was once home to Lake Lop Nur, between between the Taklamakan (left) and Kuruktag (right) deserts in China.  In the 1950′s, the lake had a surface area of about 2,000 square km (770 square miles); however, all that has remained since the 1970′s is the dry, salt-encrusted lake bed.

Lop Nur salt pans

Located in China’s resource-rich but moisture-poor Xinjiang autonomous region, Lop Nur is an uninviting location for any kind of agriculture. It sits at the eastern end of the Taklimakan Desert, where marching sand dunes can reach heights of 200 meters (650 feet), and dust storms rage across the landscape.

Yet for all it lacks in agricultural appeal, Lop Nur offers something valuable to farmers the world over: potash. This potassium salt provides a major nutrient required for plant growth, making it a key ingredient in fertilizer.

The discovery of potash at Lop Nur in the mid-1990s turned the area into a large-scale mining operation. The Advanced Land Imager (ALI) on NASA’s Earth Observing-1 (EO-1) satellite captured this natural-color image of Lop Nur on May 17, 2011. The rectangular shapes in this image show the bright colors characteristic of solar evaporation ponds. Around the evaporation ponds are the earth tones typical of sandy desert.

During the early and middle Pleistocene epoch, this area held a large brackish lake. Uplift of the northern part of the lake in the late Pleistocene created hollows that became receptacles for potash deposition. The main potash deposits found at Lop Nur today are brine potash, and this site is the second-largest source of potash in China.

Lop Nur slowly dried up in the Holocene. The area now receives average annual precipitation of just 31.2 millimeters (1.2 inches), and experiences annual evaporation of 2,901 millimeters (114 inches), according to a study published in 2008. The study found, however, that this area has experienced seven major climate changes since the end of the Pleistocene, including climatic conditions far more favorable to farming and settlement than today.