Evaluation of Some Chemical Extractants for Determination of Available Zinc for Pistachio Seedlings in Some Calcareous Soils of Rafsanjan

Vast parts of the world soils including Iran have calcareous soils in which due to the high pH and fixation of many micronutrients including zinc (Zn), the deficiency of these nutrients are seen. Total Zn content in soils does not give any information about it’s availability to plants. Therefore, available zinc in 28 calcareous soils with a wide range of physical and chemical properties was evaluated with DTPA-CaCl2, EDTA-NH4OAc, DTPA-NaOAc, DTPA-NH4HCO3, EDTA and Mehlich3 on pistachio seedling as a test plant. Experiment was done as a completely randomized design with three replications and 28 soil types under greenhouse conditions. The results showed that the ability extractants to extract zinc are as follows: Mehlich3 > DTPA-NaOAc > EDTA> EDTA-NH4OAc > DTPA-CaCl2 = DTPA-NH4HCO3. Use of multiple regression equations showed that amount extractability of Zn by some extractants from the soil by some of the physical and chemical properties soil, such as clay, CEC and CCE was dependent. There was a significant correlation between concentration and uptake zinc of the leaves and stem and extractability of Zn by the extractants . So that the amount of zinc extracted by DTPA-NH4HCO3 highest correlation (R= 0.634**) with the concentration zinc of pistachio seedlings leaf, so extractant DTPA-NH4HCO3 can be used to evaluate available zinc the pistachio in calcareous soils.