Assessment of land suitability and the performance possibility of wheat-soybean rotation in Golestan province

Land suitability analysis is a valuable application of GIS for spatial design and management. Crop rotation as a critical agricultural management is a site-specific approach that farmers implement traditionally. However, suitability of lands for cultivation of two or more crops at different time must be determined scientifically. Kamkar et al., (2014) investigated the land suitability and possibility of canola-soybean rotation for 4 basins of Golestan province. Results showed that only 11.82 percent of studied lands were suitable for implementation of canola-soybean rotation. Bidadi et al., (2015) studied the land suitability of Qaresoo basin in Golestan province for wheat cultivation. Results showed that wheat cultivation in studied area was categorized in 4 zone including very suitable, moderately suitable, poor and unsuitable. This research was conducted for agroecological zoning of Golestan province based on cultivation of wheat and soybean and for determining of suitable lands for implementation of wheat-soybean rotation. For accomplishment of this research, ecological requirements of wheat and soybean were determined using scientific resources. Minimum, maximum and average temperatures, precipitation, electrical conductivity, pH, soil texture, slope, aspect and elevation were ecological factors for determination of wheat and soybean land suitability. IRS images for 2008 and Landsat 5 images for 2011 were used to prepare the land use map for wheat and soybean. Possibility of wheat-soybean rotation was evaluated by combination of the suitability maps of wheat and soybean crops. Suitable arable lands of Golestan province for wheat were classified in four categories (suitable, moderately suitable, poor and unsuitable). Suitable class is 489538.6 ha (67.82% of total province arable lands) which is the highest proportion. For soybean cultivation, arable lands were also classified in four categories (suitable, moderately suitable poor and unsuitable). Suitable class for soybean cultivation is 362192.3 ha (50.17% of total province arable lands). Results showed that arable lands of Golestan province can be classified in 12 categories for performance of wheat-soybean rotation. Suitable wheat- suitable soybean class with 358514.1 ha (49.74% of the lands) had the highest proportion. In the other hand, the unsuitable-moderately suitable and unsuitable-suitable classes of wheat-soybean rotation with 3.52 and 11.84 ha, respectively comprises less than 1% of the total land. In general: currently, wheat-soybean rotation is conducted extensively in Golestan province despite climatic and management limitations. It is clear that breeding of early maturing cultivars of wheat and soybean is one of the most crucial steps to improve the performance of this rotation. Results revealed that using GIS can be very useful and efficient as an important tool for determination of ecological potentials of a crop.