Effects of different sources and rates of potassium on phytoremediation of a polluted soil with cadmium

Contamination of soils with heavy metals is often resulted from human activities and phytoremediation is an effective and economic strategy to remove toxic metals from soils. In order to study the effects of different sources of potassium on phytoremediation of heavy metals from a polluted soil، an incubation test and a greenhouse experiment were conducted. The polluted soil was collected from the adjacent areas of Angooran،s Lead and Zinc mining in Zanjan province. In a randomized complete block design with three replication per treatment، four levels of potassium (K) (0، 50، 100 and 200 mg K2O per kilogram of soil as KCl or K2SO4) were added to pots planted with Azargoal variety of sunflower (Helianthus annuus L.). Results showed that K application significantly (p<1%) increased DTPA-extractable (Cadmium) Cd under incubation and the differences between K2SO4 and KCl effects were significant. K2SO4 application significantly decreased soil pH، however KCl increased it. In the greenhouse experiment effects of different treatments on dry matter production of shoot and root، shoot: root ratio (S/R)، Cd concentration، its uptake and translocation factor were significant. In this study the highest amount of Cd uptake (84. 57µgpot-1) was obtained by application of 200 mgkg-1K2O as KCl. Furthermore، cultivation of sunflower decreased concentration of DTPA-extractable Cd. Therefore، this crop is suitable for phytoremediation of Cd. Also phytoremediation efficiency is improved by K fertilizer utilization. More research on this subject under field condition can be very useful and is strongly recommended.