Spate irrigation area - ha 3. Another potential source of groundwater is beneath the capital Doha itself. There are two desalination plants in Qatar. Total groundwater extraction is estimated at 188 million m . There are no national criteria for distinguishing between the size of the schemes.
Tomatoes are the main winter vegetable, melons the main summer vegetable.
The main fruit trees are dates and citrus. Alfalfa is the main green fodder crop. Barley is the main cereal, with a small quantity of wheat and maize. Over-extraction of groundwater results in a fast deterioration of the water quality, due to sea water intrusion and upward diffusion of deeper saline water. For this reason, a kind of shifting cultivation takes place within a farm, i.e., as soon as soil salinity has reached intolerable limits, new land is put into cultivation and the degraded land is completely abandoned.