NATURAL SULFATE OF POTASH, MAGNESIA
Natural Sulfate of Potash, Magnesia (2MgSO4 • K2SO4) also referred to as Sul-Po-Mag or K-Mag (these are brand names), is also a natural mineral salt, called langbeinite, and typically contains 22 percent potash, 11 percent magnesium and 23 percent sulfur. Like sulfate of potash, Sul-po-mag is soluble but is an acceptable material to use in the production of certified organic crops and the practice of organic land care.