mapping of available fe, zn, cu and mn in soils of southern tehran lands by geostatistical and gis techniques

this study was conducted to determine the spatial variability and mapping of available micronutrients iron, zinc, copper and manganese on 20,000 hectares of soils in south of tehran lands in order to identify deficiency, enough and toxicity areas. 196 surface soil samples (0-25cm) to a regular grid network of 1000×1000m were collected and extracted by dtpa and tea and concentrations of elements were measured by atomic absorption. the results showed that the micronutrient elements iron, zinc, copper and manganese have spatial variability and according to the different land utility have different concentrations. the best variogram models that were fitted for available iron and copper; exponential, zinc; gaussian and manganese; spherical. the average concentration of fe, zn, cu and mn were 2.6, 2.1, 1.2 and 3.5 mg/kg soil respectively. based on the estimated critical level in iran, all of soils have iron deficient, while for the zinc, 81 percent of the lands have a moderate, 18 percent adequate, and 1 percent high. about 76, 18 and 6 percent of the lands have a low to moderate, optimum level and high concentration of copper in the soils, respectively. available of mn in all of soils were low to moderate level. the matching of land use and management maps with mapping of each element showed that the areas with high levels of copper and zinc were in accordance with the highway, industrial and residential areas and irrigated with sewage water.