application of a proper model for creal dryland farming in northern khorasan by gis and rs capabilities

northern khorasan province is located in north-east iran. according to demarton coefficient, it is a semiarid region. arid and semi-arid or subhumid zones are characterized by temperature variations, low and erratic rainfall, periodic droughts and different associations of vegetative cover and soils. this article looks at current dry lands and general guidelines for finding the best area for dry land farming. primary map of current dry lands were provided by using tm visual images from 2002 and subject maps (plant distribution maps, topography maps…). the maps were corrected by gps and according to the dry lands. other information such as rainfalls, isotherms, height profiles, slopes, soil depth, soil erosion and soil salinity were evaluated. the layers were classified due to methods of sizes et al (1991) then the dry land area were defined three layers of optimum, average and poor performance. the map showed that the farm areas is 513886.7 ha equal to 18.2 % of the total dry lands in northern khorasan. the results showed that the studied area were used for dry land farming with suitable slope 164525.7 ha (22.05%), suitable soil, depth and texture 14295.91 ha (27.83%), optimum height layer (less than 1700 m) 411339.91 ha, with average temperature 454281.99 ha (88.2 %) and no salinity limitation 350573.79 ha (68.25). successful dry land farming is not possible in 86.1 % of dry lands in north khorasan with sharp slope, low soil depth, unsuitable soil texture and soil erosion.