Investigating Fluorine Content of Some Soils and Their Relationship with Soil Properties

Fluorine (F) is a necessary element for human and plant, however, high concentration of this element poses a risk to grazing animals and plants. Soil ingestion has been highlighted as a pathway for causing possible F toxicity in grazing animals. In this paper, total and soluble F concentrations and their relationships with selected soil properties in soils around Ahar City, East Azarbayjan Province, were studied. For this purpose, 21 composite soil samples were taken from around Ahar City and their major characteristics, total F concentration, and soluble F were measured. Results showed that the Ft and FCaCl2 concentrations ranged from 204.7- 574.3 and 0.7- 5.9 mg F kg-1soil with means of 334.8 and 4.1 mg F kg-1soil, respectively. These values were well within the range of non-polluted soils. Total fluorine showed significant correlation with total P concentrations, organic matter, and Al oxides contents of the studied soils; whereas such correlations were observed for total and free soluble fluorine concentrations with organic matter and pH, respectively. Concentration of F species in soil solution was much less than the critical concentrations of F for plants (0.3-0.5 µg/mL for oat and 32 µg/mL for tomato). In general, it seems that at normal soil ingestion rates, the soils are unlikely to cause F toxicity to grazing animals.