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A 10 gram scoop of air-dried soil and 20 milliliters of 0.01 M CaCl2. H2O (calcium chloride dihydrate) solution are boiled in a metal container for 5 minutes on a reflux extraction apparatus. Boron in the filtered extract is measured with an inductively coupled plasma optical emission spectrometer (ICP-OES). The results are reported as parts per million (ppm) of boron (B) in the soil.