Iran is located in the Northern Hemisphere, between 25° and 40° N and 44° to 63° E. Agriculture plays an important role in the economy of Iran. It accounts for one fourth of the Gross Domestic Product (GDP), one fourth of employment, more than 80 percent of food requirements, one third of non-oil exports, and 90 percent of raw materials for industries. The agriculture of I.R. Iran enjoyed an average growth rate of 5.1 percent over the two National Development Plans (1989 to 1999).

Out of the 165 million hectares that comprise the country’s area, about 37 million hectares are suitable for irrigated and dryland agriculture, of which 20 million hectares are irrigated and 17 million hectares are dryland. Of the 37 million hectares of agricultural lands, currently 18.5 million hectares are devoted to horticulture and field crop production. Of these, 6.4 million hectares are under annual irrigated crops, 2 million hectares are under horticultural crops, and about 6.2 million hectares are under annual dryland crops, while the remaining 3.9 million hectares are fallow.

The total natural resources and rangeland areas are about 102.4 million hectares, composed of 90 million hectares as pastures (in various level of forage productivity) and 12.4 million hectares as forests.

The Islamic Republic of Iran is situated in one of the most arid regions of the world. The average annual precipitation is 252 mm (one-third of the world’s average precipitation), and this is under conditions in which 179 mm or 71 percent of rainfall is directly evaporated. The annual evaporation potential of the country is between 1500 and 2000 mm. Unfortunately, in the past six years, particularly in the year 2000, some parts of the country have suffered severely from drought.

Altitudes vary from 40 m below sea level to 5,670 m above sea level and have a pronounced influence on the diversity and variation of the climate. Although most parts of the country can be classified as arid to semiarid, the country enjoys a wide range of climatic conditions. Both latitude and altitude have a major influence on climate in the various regions. This can be seen in the geographic variation of annual precipitation (from 50 mm in the central desert to 1600 mm in Gillan Province, situated at the southern coast of the Caspian Sea), and a wide range of temperatures that can vary up to 100°C (from –44°C in Borudjen/Chahar Mahal Bakhtiari Province, located in the central Zagrus Range mountains to 56°C in the south along the Persian Gulf coast). Distribution of precipitation in Iran is presented in Table 1.