Distribution of Total Concentrations of Four Soil Micronutrients in Boroojen- Faradonbeh and the Effect of Wastewater Irrigation

Mapping based on total concentrations of micronutrients may be useful in fertility management including fertilizer and/or wastewater application. The aims of this work were to (1) investigate the spatial distribution of total concentrations of copper (Cu)، zinc (Zn)، manganese (Mn) and iron (Fe); (2) to select the suitable spatial estimator; and (3) to understand the effect of wastewater irrigation on the mapping of these elements in the Boroojen-Faradonbeh plain. To this end، 200 soil samples were randomly collected from surface soil (0-30 cm) of the Boroojen-Faradonbeh plain and some soil physicochemical properties as well as total concentrations of Cu، Zn، Mn، and Fe were determined. Total concentrations were below permissible limit of each element indicating no serious issue concerning pollution. Spatial distributions of Cu، Zn، Mn and Fe were best described by a spherical variogram model while that of Mn by an exponential one. Intermediate spatial dependence of all four elements indicated the greater influence of external factors compared with internal factors. Krigging (simple or ordinary) was a better spatial estimator compared to the inverse distance method (with exponents varying from 1 to 3). The maps revealed that concentrations، particularly those of Cu، Zn، and Mn، were higher in the eastern part of the plain where wastewater irrigation is practiced. Treated wastewater application seems to be the main factor elevating the concentrations in the eastern part of the plain.