Flame photometers use atomic emission for the routine detection of metal salts, principally sodium (Na), potassium (K), lithium (Li) and calcium (Ca). A flame photometer is an instrument used for measuring the spectral intensity of metals present in the metallic salt. A flame photometer at low temperature measures the concentration of sodium and potassium present in the metallic salt. To measure the concentration of potassium present in the soil, the soil is grind and then passed through a 2 mm mesh sieve. Next, approximately 20g of air dried soil is transferred into a bottle and about 50 ml of ammonium nitrate solution is poured into it. Before shaking, this mixture is passed through a flame ionization detector. The mixture is shaken using a shaking machine for 30 minutes and at a rate of 275 strokes per minute. The shaken mixture is filtered using filter paper to retain the extract of the solution. The amount of potassium in the extract is determined using flame photometry. This is a very effective salt detection process. There are many types of flame photometers. Examples include PFP7 and PFP7/C flame photometers. A PFP7 flame photometer is a single channel photometer used for measuring sodium and potassium salts. A PFP7/C is a clinical flame photometer and is used for salt detection at low temperature. Other flame photometers are commonly available.