Soil sampling was carried out in the Velika Morava river valley, covering the area from Velika Plana to the mouth of Morava to the Danube. The composite soil samples, representing alluvial soils (22 samples), cambisols (14) and smonitzas (4), were taken from plough layers, based on a regular square grid with intervals set at 5x5 km, covering total area of 100,000 ha. The total and available fluorine contents were determined in the soils samples.

The methods for estimating Fe, Mn and Zn solubility in smonitzas over Serbia (ten localities) used as fields and meadows, were studied in this paper. The total contents of these elements were found to be nearly equal to their mean values in the world soils. Regarding their availability, investigated smonitzas were found to be well supplied with manganese and, for the majority of samples, with iron.