Zoning of Fars Province in Terms of Rain-fed Winter Wheat Cultivation Based on Precipitation and Morphological Factors

Wheat is one of the most important crops in the world and a strategic crop in Iran. The Fars province (south of Iran) is ranked first in the production of Iranian wheat. As the predominant climate of this province is warm and dry and water resources are limited¡ therefore¡ identifying suitable areas with the aim of cultivating on dry land and maximizing the utilization of rainfall can significantly optimize the water usage for irrigation. The present study was conducted to investigate the zoning of Fars Province with regard to rain-fed wheat cultivation in autumn. In most previous researches¡ in order to identifying suitable areas for rain-fed cultivation¡ only rainfall and no morphological factors such as altitude¡ slope¡ soil type and land use of the area have been considered¡ although these factors play as an important role in water infiltration to the soil and the amount of soil water holding capacity for plants. In the present study¡ in addition to precipitation¡ morphological factors were also considered. Also¡ the use of GIS software to integrate geographic information with high precision has been used in this study. Data of precipitation pertained to 10 years (2003-2013) and were collected from 24 synoptic stations in the province. The SMADA software was applied for the relevant calculations at 50% and 75% probability levels. Maps of elevation and slope angles were obtained by the Digital Elevation Map (DEM)¡ accompanied by a visional resolution of 90 meters. Results showed that the areas located in North and west parts of Shiraz¡ are suitable for rain-fed wheat cultivation. However¡ the eastern southeastern and southern regions of the province are placed in unfavorable conditions for rain-fed wheat cultivation. According to the rain-fed wheat map established in this study¡ it is concluded that the total area suitable for rain-fed cultivation is 1796000 hectares (which counts the good and very good classes at 75% probability level) in the Fars province. This is while statistics provided by the State Institute of Agriculture reported that the average area under rain-fed wheat cultivation has been only 118102 hectares for the past 13 years¡ which is indicated as non-optimal for dry land cultivation in this province.