Using Geostatistics for Zoning Areas Suitable for Saffron Cultivation in the Khorasan Razavi Province Based on Climatological Parameters

Saffron is one of the most economical and highly valuable plant species in Iran. About 80 percent of the total export of saffron in the world originates in the Khorasan Razavi province. The demand for higher production, limitations of climatologicalresources, soil and waterhave caused the officials who are in charge of agriculture to seek for areas that are potential candidates for the cultivation of saffron by means of precise, rapid and analytical methods. In the present study, geostatistical interpolation methods are used for climatological-ecological zoning of agricultural lands in the Khorasan Razavi province that are suitable candidates for saffron cultivation. To this aim, climatological and ecological requirements of saffron cultivation are first determined based on available scientific references. Then the necessary data are prepared. In the present study, an effort has been made in the spatial modeling and interpolation of the areas that are potential candidates for saffron cultivation based on the yield per unit area in 8 counties of the province during the 1989-1990 to 2008-2009 crop years and the 11 climatological parameters that affect saffron growth and blossom in the mentioned period of time. Based on the results, the maximum absolute humidity has been selected as the best covariate. The modeling of crop yield and the evaluation of the models were performed using geostatistical methods in GS+ software. Finally, the prepared zoning map showed that the geostatistical methods used are suitable choices for determination and zoning of areas that are suitable candidates for the development of saffron cultivation. The results for zoning have showed that a third of the southern areas in the Khorasan Razavi province (especially in the Gonabad county) have the maximum cultivation potential from the viewpoint of climatology, and in the northern direction of the province (especially in the Quchan and Binaloud counties) the value of land decreases considering its potential suitability for saffron cultivation.