Volume 4 Article informations Heavy metal availability and uptake by wheat crops cultivated in Tunisian field plots amended during five years with municipal solid waste compost and farmyard manure Walid Ben Achiba a,* , Noureddine Gabteni b , Gijs Du Laing c , Marc Verloo c , Naceur Jedidi a , Tahar Gallali b Abstract Agricultural recycling of municipal solid waste compost provides a valuable source of plant nutrients and organic matter. However, these wastes could have negative effects due to their metal content. The aim of the study was to evaluate the influence of the addition of Tunisian municipal solid waste compost and farmyard manure on soil metal content, availability and uptake of heavy metals by wheat crops. A long-term field experiment in four blocks with wheat crops was carried out in the north of Tunisia. The following treatments were applied in five consecutive years: 40 and 80 t ha-1 of Tunisian municipal solid waste compost, 40 t ha-1 of farmyard manure, mineral fertilization and a control plot (without amendment). In the last year of the experiment at harvest time, plant samples (grain, straw and root) and soils were collected for laboratory analyses. Results showed that the grain yields increased with the application of two organic amendments and mineral fertilization. The farmyard manure had no effects on the heavy metal contents in soil and in wheat plants. Municipal solid waste compost increased the concentration of Cd, Pb, Cu and Zn and had no effects on Ni and Cr concentrations in soils. In wheat plants, the roots accumulated and retained the heavy metals. Only small portions of Cu, Zn and Ni reached the straw, whereas only Cu and Zn reached the grain. The availability of heavy metals in the soil was evaluated using an NH4OAc-EDTA pH 4.65 solution for metal extraction. Results showed that the long-term application of municipal solid waste compost increased the available heavy metals. The highest rate (80 t ha-1 ) of compost caused a greater mobility compared to the farmyard manure amended soils and the control soil. Significant correlations were obtained between NH4OAc-EDTA extractable heavy metals on the one hand and the concentrations of Cu, Zn and Ni in the roots and Ni in the straw of the wheat plants on the other hand. Key words: Municipal solid waste compost, farmyard manure, soil heavy metals, NH4OAc-EDTA, uptake, wheat crops.