Effects of Cattle Manure, Chemical Fertilizers, and Their Combination on Cadmium Accumulation and Growth of Purslane (Portulaca eoleracea)

Vegetables are among the major sources of cadmium entering the human food chain, which can be a serious threat for human health. So, in order to evaluate effects of organic manure, chemical fertilizers, and their combination on cadmium accumulation and growth of purslane, a factorial experiment was conducted in completely randomized block design with three replications, in 2012. Fertilizer treatments included urea fertilizer (60 and 120 mg N kg-1 soil), cattle manure (60 and 120 mg N kg-1 soil) , combined fertilizer (60, 45, 30 mg N kg-1 soil as urea fertilizer and cattle manure), and the control (no N amended). These were evaluated undertwo cadmium levels (no cadmium and 10 mg kg-1soil). Results indicated that concentration and uptake of cadmium in plant, decreased with increasing N rate, especially of cattle manure, and the lowest cadmium concentration was observed in 120 mg kg-1 in the form of cattle manure. Increase in nitrogen application from any source increased concentration and uptake of nitrogen. The greatest yield was obtained in 120 mg N kg-1 as cattle manure. There was no significant difference between 120 and 90 mg N kg-1 in the form of urea and the combined (1:1) fertilizer. In general, it can be concluded that use of cattle manure in vegetables production prevents movement of soil cadmium into vegetables and it is an effective method for protecting food chain from Cadmium contamination.