Zinc adsorption was studied for ten selective representative soils according the difference amount of clay content, calcium carbonate and organic matter in Duhok governorate, Iraqi-Kurdistan region included (Kanimasi-1&2, Batofa, Zakho, Assih, Semeel, Khanke, Faydi, Zawita and Bamarny locations). Samples were air dried and sieved through a 2-mm sieve to study the physical and chemical characteristics of the soils, forms of zinc and it’s adsorption. Results showed the soluble, DTPA extractable zinc (available), CaCl2 extractable zinc (exchangeable) and total zinc ranged between (0.29 – 0.94), (0.88 – 1.64), (1.71 – 2.05), and (12.25 – 56.15) mg kg-1 respectively. Negative significant correlation found between soluble zinc with pH, also negative significant correlation found between DTPA extractable zinc with exchangeable potassium, bicarbonate and available phosphorus but positive significant correlation found between CaCl2 extractable zinc with pH, total–Zn negatively affected with pH and positively with HCO3 and sand. Results demonstrated that by increasing added zinc concentration to studied soil zinc will be adsorbed zinc adsorbed greatly at temperature 25°C and 48°C. In general total zinc adsorbed at 25C° in six concentrations was less than zinc adsorbed at 48C°. At temperatures 25°C and 48°C the high total amount of zinc adsorbed found in the soil of Zawita and Zakho respectively, but the lower total zinc adsorbed observed in soil of Batofa and Kani masi-2. The quantity of adsorption affected positively by presence of clay, calcium carbonate, active calcium carbonate and cation exchange capacity and negatively affected by the ion concentration of bicarbonate, calcium, potassium, organic matter and sand content.

Zinc desorption studied for ten soils was variance in calcium carbonate, clay percent, and organic matter from Duhok province in the north of Iraq involved (Bamarny, Zawita Assih, Semeel, Kanimasi-1& 2, Khanke, Zakho, Batofa, and Faydi, locations). Soil testers after air dried up ground and filtered through a 2-mm sieve was taken to know the properties of the soils, zinc forms and desorption. Results showed the soluble, available, exchangeable and zinc total alternated among (0.29 - 0.94), (0.88 - 1.64), (1.71 - 2.05), and (12.25 - 56.15) mg.kg−1 one-to-one, Zn desorption raise with the raising of Zn added to research soils, extraction concentration CaCl2 from 0.1 to 1 molarity and temperature. Higher quantity of Zn release at 298K, was found in the soil of Kanimassi-1 (31.40 - 264.81) μg. g−1 at 0.1M, 1M CaCl2 extraction respectively, it may be owing to the high value of available phosphorus, CEC and organic matter and lower quantity of available-Zn and CaCO3. But the lowest amount observed in Faydi soil (14.10-118.69) μg. g−1. The high desorption of Zn at 321K, noted in Faydi soil between (50.50 - 421.00) μg. g−1 and low amount in Semeel soil between (26.35 - 222.10) μg.g−1 at 0.1 to 1M CaCl2 extraction respectively, designated Zn released more with increasing temperature. In general low quantity of Zn releases as of all researched soils causes to the great amount of CaCO3, quality and amount of clay minerals dominant that cause raise Zn bonding also low desorption from all studied soils. The effect of CaCl2 extraction concentration to increase Zn desorption was more than the effect of temperature in all soils.