Plant residue is an important source of micronutrients and its return to soil plays an important role in the nutrients cycle. In addition, decomposition of organic matters via changes in pH of soil and release of chelating compounds causes the changes of elements speciation in soil. Considering the fact that speciation of elements in soil plays an important role on phytoavailability in plants, this research was conducted with the aim of studying the effects of plant residue management and type of pre-crop plants on dissolved organic carbon and amino acid concentrations in rhizosphere of two wheat genotypes, zinc speciation in soil solution and zinc concentration in wheat grain in a farm setting. This study was conducted in Rudasht research station for two continues years. Pre-crop treatments consisted of four different plants species, Sunflower ( Heliantus annus L.), Sorghum ( Sorghum bicolour L.), Trifolium ( Trifolium pretense L.), Sofflower ( Carthamus tinctorirus L.) and without pre-crop plant treatments. Seventy days after plantation, pre-crop plants were harvested, air dried and applied to half of the each test plot with the rate of seven tons per hectare. After two weeks of plant residue application, two genotypes of wheat, Back Cross and Kavir were planted. After plant maturity, the plants were harvested and zinc concentration was measured in wheat grains. In evaluation of effect of residue management on zinc speciation in solution, soil sampling was performed in three stages: 1) After harvesting of preceding-crop plants and prior to addition of their residue to soil, 2) Wheat tillering, 3) Wheat harvesting and concentration of dissolved organic carbon was measured. Speciation of soil solution was determined using visual MINTEQ software. Concentrations of rhizosphere amino acids were measured at wheat harvesting stage. Results show that in two consecutive years of this study, application of plant residue in comparison with no plant residue treatment caused an increase in dissolved organic carbon and rhizosphere amino acids. Overall, more decomposition of Sunflower and Trifolium residues caused a significant increase in concentration of dissolved organic carbon in soil solution. Sorghum and Trifolium residues showed the highest and lowest effect on increased concentration on total soil amino acids respectively. Based on the results of this study, increased zinc speciatio in soil solution consists of Zn 2+ , Zn-DOC, ZnCl + , and ZnCO 3(aq) . Use of pre-crop residue in comparison with no residue application caused a significant decrease in percentage of ZnCl + , and Zn 2+ and an increase in Zn-DOC, and ZnCO 3(aq) .In essence, decomposition of plant residue in soil with production of chelating compounds caused the formation of organic zinc complexes and decrease in ZnCl + , and Zn 2+ . Concentration of dissolved organic carbon and amino acids in soils that Back Cross was planted was higher than Kavir. However, effect of wheat genotype on percentage of prevalent Zinc samples in soil solution, is dependent on year of plantation, type of plant residue, and timing of samples taken. Results of this study show that, the highest and lowest effect of residue usage in increased concentration on grain zinc concentration are on Sorghum and Sunflower and as such there was no significant difference noted between Trifolium and Sofflower. Key words: plant residue management, preceding-crop, dissolved organic carbon, amino acid, zinc speciation, wheat.