GIS-based assessment of land suitability for alfalfa cultivation: a case study in the dry continental steppes of northern China

Alfalfa (Medicago sativa L.) is the most valuable perennial forage grass in northern China. We selected 12 ecological criteria and 4 socioeconomic criteria to calculate the suitability of land for alfalfa cultivation in the Xilingol League of the Inner Mongolia Autonomous Region. We combined ecological suitability assessment with fuzzy analysis to standardize the criteria. We used the analytical hierarchy process to determine the weight of these criteria, and used multi-criterion decision analysis (MCDA) to aggregate the criteria. We then calculated the suitability score for each evaluation unit. The suitability was divided into highly, moderately, and marginally suitable, or unsuitable, using the geoprocessing module of ArcGIS 9.3 according to the FAO land suitability classification. We found that highly suitable areas covered 10,799.84 km2, accounting for 5.3% of the total area, and unsuitable areas covered 99,235.87 km2, accounting for 48.9% of the total area. Combining the fuzzy analysis method with the theory of ecological suitability and the MCDA method to evaluate the suitability of land for alfalfa cultivation provided insights that can guide decisionmakers and farmers to make more practical and scientific decisions