Find in Library

BACKGROUND Determination of ammonium nitrogen and nitrate nitrogen in soil makes great sense for indication of the nutrient status and environment evaluation of soil. The standard methods based on spectrophotometry are susceptible to interference from the color of the extraction test solution, turbidity, and other coexisting ions. Moreover, those methods are time-consuming due to the demand of decoloration. OBJECTIVES To establish a convenient and high sensitivity method for the determination of ammonium nitrogen and nitrate nitrogen in soil, based on simultaneous extraction. METHODS Ammonium nitrogen and nitrate nitrogen in soil were simultaneously extracted with KCl solution without decoloration, and determined by gas phase molecular absorption spectrometry. RESULTS 50 samples were determined within 5h due to the avoidance of the color reaction process. The dynamic linear ranges of ammonium nitrogen and nitrate nitrogen were 0.10-2.00mg/L and 0.20-4.00mg/L, respectively. The detection limits were 0.013mg/kg and 0.002mg/kg, respectively. The recoveries ranged from 96.3% to 100.7%, and the relative standard deviation was below 1%. CONCLUSIONS Compared with the national standard method based on traditional spectrophotometry, this method has significantly improved the detection limit, precision and recovery. The method can be widely used in the field of detection of ammonium nitrogen and nitrate nitrogen in farmland soil.