The Investigation of Heavy Metals (Lead, Zinc, Manganese and Iron) Concentration Variation in Soil and Lepidium sativum L. Shoots under Organic and Mineral Treatments

Intensive agriculture and industrial activities in several parts of Iran have reduced soil quality. This research was conducted to investigate the effect of organic and mineral amendments on polluted soil around the Angouran zinc and lead mines. The experimental treatments included two organic treatments: bagasse and rice husk at three levels, namely 1.25%, 2.5% and 5%, and three minerals treatments as follows: zeolite in three levels (5%, 10% and 15%); phosphate rock at three rates (1%, 3% and 5%); and triple superphosphate in three ratios (0.0075%, 0.015% and 0.3%) accompanied with the control treatment. After three months incubation, the heavy metal (lead, zinc, iron, manganese) concentrations were measured. After that, garden cress was planted in pots and, after completing its vegetative period and harvesting it, heavy metals in the garden cress shoots were measured. The results of data Analysis of Variance (ANOVA) showed that the treatments had a significant effect on the reduction of heavy metal concentration in the soil and in garden cress shoots. The least lead concentration (28.17 mg kg⁻¹) was observed in the first level of rice husk and the highest reduction percentage of zinc concentration (34%) in garden cress shoots was found in the second level of rice husk. According to the effect of organic treatments on heavy metals fixation in soil and reduction of plant uptake, usage of organic matter in polluted soils can be a useful way to control the transfer of pollutants.