Copper is an essential microelement for plants. Soil organic matter content and copper (Cu) are low in most cultivated soils of Iran. Sequential extraction has been used as a suitable method for identification of chemical forms of heavy metals and their potential plant availability. Little information is available about the distribution of Cu in calcareous soils of Iran. A greenhouse experiment was conducted to study the effects of organic matter and Cu on chemical forms of Cu in two calcareous soils Chitgar (S1) and Kamfirooz (S2), of Iran. Treatments consisted of municipal waste compost (K), and cow manure (G), without organic matter (Con) and two levels of Cu, i.e., 0, 5 mg Cu kg-1 soil in the form of CuSO4..H2O. The greenhouse study was a factorial experiment arranged as a completely randomized design with three replications which lasted for 8 weeks. Application of organic matter and Cu had significant effects on both soils. Copper mainly occurred in residual fraction in both soils. However, carbonate and organic fractions were also remarkable. Application of organic matter increased organic fraction of both soils. Application of Cu decreased residual and increased carbonate Cu.

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