Evaluation of Soil Degradation Impact on Wheat Yield by Geographical Information System

Soil degradation and its relation to wheat yield were analyzed in a 1041.2-ha catchment in Ustic soil moisture regime in north-central Anatolia, Turkey. The soils in the study area were sampled based on a randomized sampling scheme, using 142 samples from topsoil and 115 samples from subsoil. All the soil samples were analyzed for sand, silt, clay, coarse material (material with a diameter of >2 mm), soil organic matter, phosphorous, nitrogen, boron, zinc, iron, electrical conductivity, pH, hydraulic conductivity, and cation exchange capacity. Wheat yield was measured at 115 sampling locations. Data were evaluated by global information system (GIS) will and variable reduction (factor analysis) techniques. The majority of the soil properties exhibited high variation with a skewed distribution. Low organic-matter content, high penetration resistance, low water-holding capacity, and deficiency in some macro- and microelements were the most important factors limiting wheat yield.