Deriving Crop Production Functions to Estimate Wheat Virtual Water and Irrigation Water Price

The water resources deficiency in Iran and sequential drought events are challenging water resources security in order to cultivate strategic crops such as wheat. In the other hands, huge amount of wheat import to the country necessitates to heed more attention to wheat virtual water and its costs. The objectives of this study were to determine the amount of green and blue virtual water of wheat, irrigation water price and virtual water flow in Iran and in particular in Fars province for ten consecutive years. Consequently, the cultivated area, crop production and precipitation data were collected from ministry of Agriculture and Iran’s Meteorological Organization for the period of 2000 to 2010. The potential evapotranspiration of wheat was extracted for each and every province using NETWAT software package. After calculating the actual evapotranspiration with FAO crop water production function, the effective rainfall as well as the blue and green virtual water and irrigation water price were determined. The results indicated that shifting the land use from dry farming to irrigated cultivation and management missteps in water and soil resources operation and maintenance without considering the climate have increased the irrigated area, virtual blue water and costs being followed by decreasing dry farming cultivation area, virtual green water and crop yield in Fars province. Although the irrigated area was increased in the final two years in country scale, the irrigated yield was reduced which increased virtual blue water and costs. There exists no scientific, economic, environmental and practical explanation for this outcome and the costs which imposed on the government and people are not returnable.

کلیدواژه ها:

FAO crop - production function ، changing land use ، wheat irrigation requirement ، NETWAT