Research Progress of Rapid Detection for Available Potassium in Soil by Turbidimetry
A turbidimetry-based method was developed to rapidly detect available potassium in soil.The solution of NaHCO3—Na2SO4—NaOH—DTPA was used to extract soil available potassium,the solution of 0.02 mol/L cupric sulfate was used to mask ammoniumion,and the solution of 0.20 mol/L EDTA acid disodium salt was used to eliminate the interference of metal ions.The soil turbidity solution was determined at 680 nm after 10 min of reaction time.The result showed that the range of available potassium was from 1.30×10-5 to 3.12×10-4 mol/L,and the detection limit was 2.29×10-6 mol/L.The recovery rate of soil available potassium was 90.71％-109.14％,and RSD was 2.61％-4.32％.The available potassium was determined in 161 soil samples from Xinjiang,Inner Mongolia,Sichuan,Hunan and Henan Provinces.Compared with the flame photometer method in NY/T889-2004,the regression equation was y=0.6437x-3.5714,and the correlation coefficient was r=0.9732.Overall,this method could be applied to the rapid detection of soil available potassium.
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