A proposed new approach to identify limiting factors in assessing land suitability for sustainable land management

Making optimal use of scarce resources in developing countries is a major challenge for sustainable crop production. Characterization of factors limiting crop production is an important step in meeting this challenge. We outline and test a new method to identify characteristics of land limiting maize production in 61000 ha of the Qazvin province, northern Iran. Several soil profiles and augers were then investigated on soil samples collected from horizons of 21 representative profiles and analyzed for soil properties, such as particle size distribution, exchangeable sodium percentage, electrical conductivity, soil pH, organic carbon content, calcium carbonate equivalents, gypsum, and cation exchange capacity. Soil mapping units were surveyed and separated in the study area. Climatic, soil, and landscape characteristics were rated according to their likely influence on maize growth. Limiting characteristics included drainage, salinity/alkalinity, pH, coarse fragments, calcium carbonate equivalents, and slope. Our method shows the type and magnitude of limitation and as such is an improvement over existing approaches that only show where limitation is occurring. Our method lends itself to making transparent and quicker decision for the sustainable production of crops