Excessive phosphorus fertilization does not increase cadmium concentrations in soil or carrots (Daucus carota L.) grown in Konya (Turkey)

The relationships between soil nutrient concentrations, plant nutrient contents, and soil properties were investigated in carrot (Daucus carota L.) fields in Konya-Kasnhan (Turkey). The soils were high in clay content, slightly alkaline, and were moderate to high in CaCO3 content. The soils had sufficient N, Ca, Mg, K, and Fe, but did not have adequate Zn or B for plant growth. The carrots had moderate to high concentrations of Mg, B, Fe, and Zn; however, they had low concentrations of K, Ca, and N. The Cd-content of the soils ranged between 0.06 and 0.91 mg/kg (with a mean of 0.33 mg/kg). The Cd-content of the carrot leaves and organic matter content of the soils were significantly correlated (r= - 0.351, p0.05). Zinc deficiency is a major problem in carrot fields of Konya. Excessive phosphorus fertilization did not seem to result in Cd-pollution of soil or potentially toxic Cd-levels in carrots. The high pH and CaCO3 contents of the calcareous soils lead to stabilization of heavy metals; however, they also result in reduced availability of many plant nutrients. Consequently, soil-management practices, which will increase the availability of plant nutrients in calcareous soils, need to be investigated. Sulfur fertilization could be a way to reduce soil pH to neutrality as a result of oxidation of added sulfur temporarily in calcareous soils.