Potential of rain-fed farming in abandoned dryfarmings based on climatic and physical factors (case study: Taleghan basin)

From the total 12/6 million hectares of dryfarming through the country, approximately 4 to 5 million hectares classified as dryfarming which located in steepic lands and generally having low output or known as abandoned lands. These lands have special characteristic like minimum yield, and high erosion which loose a part of fertilize top soil yearly. Since factors like annual rainfall, slope, soil depth, and landuse are effective elements in considering the proportion of dryfarmings, therefore regarding maps of Taleghan land use (2001), isorain, slope and soil depth suitable and non suitable areas for dryfarming in Taleghan were distinguished. Then field control was performed. Based on climatic investigations, it was found that there is no limitation in view point of raining for rain feeding in Taleghan. Results obtained from maps and field controls demonstrated that 28.5% of Taleghan dryfarmings is covered by areas without rain limitation. 71.5% of dryfarmings were known as non-suitable areas for rain feeding. Based on the results of this research it is emphasized that 3 conditions are very important for rain feeding; mean annual rainfall more than 300 mm, enough soil depth, and slope lower than 12%.