applying tire rubber ash enriched cow manure as a useful way to decrease canola cd uptake in a polluted soil

Background: cadmium (cd) is a toxic heavy metal that affects plant growth and human health. therefore, it is necessary to reduce its concentration. objectives: this research was done to investigate the role of tire rubber ash enriched cow manure application to reduce cd uptake by canola. methods: treatments were consist of applying three levels of cow manure (0, 10 and 20 t ha^-1), two levels of tire rubber ash (0 and 200 kg ha^-1) in a cd polluted soil (0, 5, 10 and 15 mg cd (kg soil)^-1). the cd and zinc (zn) concentration of canola was measured using atomic absorption spectroscopy. this research was done as a factorial experiment in the layout of completely randomized block design with three replications. results: applying 20 t ha^-1 tire rubber ash enrichedcowmanurein 10mgcd(kg soil)^-1 polluted soils decreased rootcdconcentration by 30.1%, while the root zn concentration was increased by 17%. in addition, applying the above amount of organic amendment in 15mgcd (kg soil)^-1 polluted soils decreased grain cd concentration by 45.7%, while the grain zn concentration was increased by 27%. in addition, the aboveground biomass of plant was also increased by 30%. conclusions: the results of this study showed that enrichment of cow manure with tire rubber ash can decrease plant cd concentration in cd polluted soils (interaction effects of cd and zn), that is a positive point in environmental research. however, the type of plant and amount of pollution could not be ignored.