Abstract
Experiments were conducted to study the forms of Co, and its relations with some physical-chemical properties of some calcareous virgin soils of Kurdistan region. Soil samples were taken at(0-30)cm depth from 12 different sites .The some chemical and physical properties, and the amount of total and different forms of cobalt were determined.
Total Co in soils varied widely from (32 to 47) mg.kg-1 soil .The statistical analyses has shown that each of total carbonate, active lime, CEC, Fe, Mn oxides , clay amount and organic matter has a significant role in determining of total Co .Water soluble Co varied between (0.01 to 0.63) mg.kg-1 and exchangeable Co extracted with NaOAc ranged (0.06 – 0.7 5) mg.kg-1soil , whereas , exchangeable Co extracted with acetic acid ranged ( 9.33 to 24.96) mg.kg-1 soil .There were a positive significant correlation between exchangeable Co and total Co, CEC, clay and organic matter content , and a negative significant correlation with pH ,total carbonate and active lime.
Chelating Co extracted with (TPA+CaCl2+ TEA) ranged (0.17 to 2.36) mg.kg-1 soil and it has a negative significant correlation with total carbonate, active lime, pH, and a positive significant correlation with organic matter, Co bound to organic substance and CEC.
Easily reducible Co which is bound to Fe and Mn ranged (3.97 to 13.05) mg.kg-1 soil and has a high positive significant correlation with clay, organic matter, CEC ,water soluble Co, and chelating Cobalt , and has a negative significant correlation with pH, total carbonate, active lime .
Oxidisable Co which bound to organic substance ranged (4.55 to 8. 53) mg.kg-1 soil and has a high negative significant correlation with clay, organic matter, chelating Co, and positive significant correlation with pH, total carbonate and active lime.
Co bound to non-silicate metals ranged (2.75 to 10.16) mg.kg-1 soil. These values have a high negative significant correlation with clay, organic matter, and positive significant correlation with pH, total carbonate and active lime.