Four extractants, DTPA, EDTA, IN NH4OAc and 0.1N HCl were evaluated on the basis of their ability to predict Zn and Cu deficiencies using nine Saskatchewan soils and alfalfa as a test crop. The DTPA test was found to be most suitable as an index of Zn deficient soils with a “critical”; value for Zn deficiency of 1.1 μg/g of soil. Although the results obtained for Cu were inconclusive, preference of the DTPA test is given for routine analyses. The approximate “critical”; level in the latter case is 0.5 μg/g of soil.