Boron is available on the market in a number of different compounds. Since the amount of boron contained in each compound is different, the concentration will determine the rate required per acre. Frequently, all of these boron-containing compounds are erroneously referred to as borax (11.36 percent boron).
Miller, Harold F., "Borax, Borates, and Other Boron-Carrying Compounds" (1964). Agronomy Notes. 157.