in water, but the salty/bitter taste makes liquid supplements unpalatable. typical doses range from 10 mmol (400 mg), to 20 mmol (800 mg). potassium is also available in tablets or capsules, which are formulated to allow potassium to leach slowly out of a matrix, since very high concentrations of potassium ion that occur adjacent to a solid tablet can injure the gastric or intestinal mucosa. for this reason, non-prescription potassium pills are limited by law in the us to a maximum of 99 mg of potassium. a meta-analysis concluded that a 1640 mg increase in the daily intake of potassium was associated with a 21% lower risk of stroke. potassium chloride and potassium bicarbonate may be useful to control mild hypertension. in 2020, potassium was the 33rd most commonly prescribed medication in the u.s., with more than 17 million prescriptions. detection by taste buds potassium can be detected by taste because it triggers three of the five types of taste sensations, according to concentration. dilute solutions of potassium ions taste sweet, allowing moderate concentrations in milk and juices, while higher concentrations become increasingly bitter/alkaline, and finally also salty to the taste. the combined bitterness and saltiness of high-potassium solutions makes high-dose potassium supplementation by liquid drinks a palatability challenge. commercial production mining sylvite from new mexico monte kali, a potash mining and beneficiation waste heap in hesse, germany, consisting mostly of sodium chloride. potassium salts such as carnallite, langbeinite, polyhalite, and sylvite form extensive evaporite deposits in ancient lake bottoms and seabeds, making extraction of potassium salts in these environments commercially viable. the principal source of potassium – potash – is mined in canada, russia, belarus, kazakhstan, germany, israel, the u.s., jordan, and other places around the world. the first mined deposits were located near staßfurt, germany, but the deposits span from great britain over germany into poland. they are located in the zechstein and were deposited in the middle to late permian. the largest deposits ever found lie 1,000 meters (3,300 feet) below the surface of the canadian province of saskatchewan. the deposits are located in the elk point group produced in the middle devonian. saskatchewan, where several large mines have operated since the 1960s pioneered the technique of freezing of wet sands (the blairmore formation) to drive mine shafts through them. the main potash mining company in saskatchewan until its merge was the potash corporation of saskatchewan, now nutrien. the water of the dead sea is used by israel and jordan as a source of potash, while the concentration in normal oceans is too low for commercial production at current prices. chemical extraction several methods are used to separate potassium salts from sodium and magnesium compounds. the most-used method is fractional precipitation using the solubility differences of the salts. electrostatic separation of the ground salt mixture is also used in some mines. the resulting sodium and magnesium waste is either stored underground or piled up in slag heaps. most of the mined potassium mineral ends up as potassium chloride after processing. the mineral industry refers to potassium chloride either as potash, muriate of potash, or simply mop. pure potassium metal can be isolated by electrolysis of its hydroxide in a process that has changed little since it was first used by humphry davy in 1807. although the electrolysis process was developed and used in industrial scale in the 1920s, the thermal method by reacting sodium with potassium chloride in a chemical equilibrium reaction became the dominant method in the 1950s. na + kcl → nacl + k the production of sodium potassium alloys is accomplished by changing the reaction time and the amount of sodium used in the reaction. the griesheimer process employing the reaction of potassium fluoride with calcium carbide was also used to produce potassium. 2 kf + cac2 → 2 k + caf2 + 2 c reagent-grade potassium metal costs about $10.00/pound ($22/kg) in 2010 when purchased by the tonne. lower purity metal is considerably cheaper. the market is volatile because long-term storage of the metal is difficult. it must be stored in a dry inert gas atmosphere or anhydrous mineral oil to prevent the formation of a surface layer of potassium superoxide, a pressure-sensitive explosive that detonates when scratched. the resulting explosion often starts a fire difficult to extinguish. cation identification potassium is now quantified by ionization techniques, but at one time it was quantitated by gravimetric analysis. reagents used to precipitate potassium salts include sodium tetraphenylborate, hexachloroplatinic acid, and sodium cobaltinitrite into respectively potassium tetraphenylborate, potassium hexachloroplatinate, and potassium cobaltinitrite. the reaction with sodium cobaltinitrite is illustrative: 3 k+ + na3 → k3 + 3 na+ the potassium cobaltinitrite is obtained as a yellow solid. commercial uses fertilizer potassium sulfate/magnesium sulfate fertilizer potassium ions are an essential component of plant nutrition and are found in most soil types. they are used as a fertilizer in agriculture, horticulture, and hydroponic culture in the form of chloride (kcl), sulfate (k2so4), or nitrate (kno3), representing the 'k' in 'npk'. agricultural fertilizers consume 95% of global potassium chemical production, and about 90% of this potassium is supplied as kcl. the potassium content of most plants ranges from 0.5% to 2% of the harvested weight of crops, conventionally expressed as amount of k2o. modern high-yield agriculture depends upon fertilizers to replace the potassium lost at harvest. most agricultural fertilizers contain potassium chloride, while potassium sulfate is used for chloride-sensitive crops or crops needing higher sulfur content. the sulfate is produced mostly by decomposition of the complex minerals kainite (mgso4·kcl·3h2o) and langbeinite (mgso4·k2so4). only a very few fertilizers contain potassium nitrate. in 2005, about 93% of world potassium production was consumed by the fertilizer industry. furthermore, potassium can play a key role in nutrient cycling by controlling litter composition. potassium citrate potassium citrate is used to treat a kidney stone condition called renal tubular acidosis. potassium chloride