Micronutrient testing of plant growth media: Extractant identification and evaluation

Using saturation extract procedures, fifteen extractants were evaluated for their ability to remove B, Fe, Mn, and Zn from a peat and vermiculite (50:50% by volume) medium amended with three levels of micronutrients. A modified saturated media extract test procedure was developed in which 30 ml of .005M DTPA was added per 100 cc of sample to be extracted. The use of this method enhanced resolution of micronutrient cation test levels in 3 media while producing only minor changes in macronutrient, pH, or soluble salt test results when compared to DI water extractions.