The effect of TMU and Geopedology working units in soil degradation mapping

Some noticeable areas of valuable land resources are degraded every year, due to improper management of land use activities. Soil degradation includes reduction of soil productivity or its nutrients loss by soil erosion. This research was executed in Honam sub-basin, located in Lorestan Province to study the soil quality degradation and mapping. The study area was segmented to unique soil degraded polygons, as working units, using TMU and Geopedology methods. Soil was sampled in each working unit and their organic carbon, total nitrogen, available phosphorus and potassium, bulk density and micronutrients such as Iron, Zinc, Manganese and copper were measured. Quality control charts were drawn for all measured soil specifications in each working unit. Soil degradation indices and their types, causes, degrees, extents and severities were determined by GLASOD model and consequently, soil degradation map were provided. For statistical comparison, soil degradation maps resulted from TMU and Geopedology work units were compared with ground control points using Vilkaksen and paired comparison tests. Results demonstrated that there are 46 types of working units at 61 locations in TMU working units map. These numbers are 45 types at 94 locations in Geopedology working units map. The accuracy of soil degradation maps provided from TMU and Geopedology methods were 66.3 and 68.9 percent, respectively. From precision view of point, coefficient of variation in work units of TMU and Geopedology methods were 25.58 and 30.26 percent, respectively. Results showed that there are no significant difference between fertility degradation degree of ground control points and TMU working units in both tests. Also, results showed that there are significant difference between fertility degradation degree of ground control points and Geopedology working units in both tests.