A kitchen garden soil was sampled in a contaminated urban area located in the north of France. Samples were air-dried and crushed to pass through a 10-mm stainless steel sieve. Due to the high heterogeneity of garden soils in the studied area, much attention have been paid on the homogeneity of soil samples. After this step, the mass of sampled soils (48 kg) was divided to obtain four subsamples Each of them was divided in six replicates, unamended or amended using dicalcium phosphate (DCP) or monocalcium phosphate (MCP) or a mixture of these two compounds (MxP=75%DCP+25%MCP) The phosphorous amendments were added into the soil in small quantity (0.02 %) with the aim at reducing the environmental availability of carcinogenic metals and to increase the Zn availability (Figure 1) After the stabilisation period (2 months) in a greenhouse, 1 5 g of ryegrass seeds (Lolium perenne L.) were sown in the 24 containers. Eight weeks after sowing, ryegrass shoots were harvested, oven-dried at 40 °C and calcined at 500 °C in a muffle furnace (Nabertherm P330, Lilienthal, Germany).