Potassium ( K ) is one of the three major nutrient involve by plant life , the others being nitrogen ( N ) and phosphorus ( P ) . In the soil surround , potassium be in three different forms . Plants only absorb potassium ions ( K+ ) in one form call exchangeable potassium , provided by moist clay particles or organic matter . Fixed atomic number 19 is " operate up " in parent cloth like mica or felspar mineral , accounting for over 90 percent of all potassium reserves in grunge . Non - exchangeable atomic number 19 is an average form between fixed and exchangeable forms .
Soil Parent Material
The principle beginning of potassium in soils are the minerals called feldspar and mica , agree to the author of " Soils and Soil Fertility . " If natural soils have been made over ions from these minerals , potassium levels will be gamy . no matter if the garden soil is sandlike , loamy or the Great Compromiser , the spillage of atomic number 19 from fixed to intermediate non - standardised forms is firm when the soil mote are little . the Great Compromiser soil corpuscle are much smaller than guts particles .
Weathering
Weathering of feldspar and mica in the dirt causes the breakdown of atomic number 19 from fixed to non - standardised to exchangeable ( plant useable ) forms . Mica releases K more easy than felspar . Although leach of atomic number 19 is tedious or minimal , regions where the climate is humid and wet run to have lower amounts of works usable K . Leaching is quicker where lifelike moisture is prevalent . In the easterly United States , granger add together potassium fertilizers to soil whereas in the westerly United States where rain and humidity are lower , K often remain in much higher levels in the soil in all shape . Only in heavily water fields in the American West are potassium levels fall .
Abundance of Organic Material
When talk about only plant - useable K , the K ion is positively charged and is most easily absorbed into ascendant when the soil is not dry or pH not alkaline . Exceptions always exist ; some wet , ill draining alkaline Lucius DuBignon Clay soils can tie down K , constitute it difficult for plants to utilize . Decaying plant cloth replenishes soils with a hatful of potassium ion . Therefore , if a dirt is amended with copious amounts of compost , for example , and plant develop and naturally die and decomposition , uncommitted potassium levels will be high . Conversely , if constitutive issue is deficient , or no plants grow in the soil , the amount of available potassium may be quite miserable even if the fixed K levels are high . If soil moisture is lacking , consumption of potassium by roots is diminished and the amount of potassium ions that remain in the ground ’s visibility is higher .
Fertilizer Application
Since strip of atomic number 19 is slow in soil , even applications of potassium - robust fertilizers over long periods can increase amounts of exchangeable K in the soil . Research in 1966 , cited in " Soils and Soil Fertility , " revealed that 77 class of craw fertilization in a loam land in New York increased atomic number 19 uncommitted to plant in the top 2 feet of top ground . This was mention in craw fields where both beast manure ( organic thing ) and synthetic ( adult male - made ) fertilizer were applied .
