This experiment was conducted to study the variation of active iron (Fe) content in leaves of satsuma mandarin (Citrus unshiu) grown in the calcareous soils of eastern Mazandaran. The experiment was conducted in split factorial in the form of a randomized complete block design with four replications. The main factor was date (March 16, April 25, June 5 and July 16), and the sub factors were soil (three soils with different calcium carbonate content) and rootstock (sour orange, citrumelo and troyer citrange). Results indicated that bicarbonate concentration was different in four dates. Bicarbonate concentration reduced in date four and in soils one and two; however, it increased in date four and soil three, and in the second sampling date, bicarbonate concentration was higher in soil three than other soils. Generally, the highest active Fe content was achieved in date four, soil one and troyer rootstock.
