Simultaneous determination of soil aluminum, ammonium- and nitrate-nitrogen using 1 M potassium chloride extraction

Determination of soil aluminum (Al), ammonium-nitrogen (NH4-N), and nitrate -nitrogen (NO3-N) is often needed from the same soil samples for lime and f ertilizer recommendations, but Al has to be extracted and quantified separa tely from NH4-N and NO3-N according to present methods. The objective of th is study was to develop a reliable method for simultaneous analyses of soil Al, NH4-N and NO3-N using a Flow Injection Autoanalyzer. Thirty-five soil samples from different locations with wide ranges of extractable Al, NH4-N and NO3-N were selected for this study. Aluminum, NH4-N and NO3-N were extr acted by both 1 M and 2 M potassium chloride (KCl), and quantified using a LACHAT Flow Injection Autoanalyzer simultaneously and separately. One molar KCI was found to be a suitable extractant for all three compounds when com pared to 2 MKCl. The 1 MKCl extract proposed could aid in decreasing the co sts associated with simultaneous NH4-N, NO3-N, and Al analyses. Results of those three compounds analyzed simultaneously were not statistically differ ent from those analyzed separately in 1 MKCl solution. This new procedure o f simultaneous determination of NH4-N, NO3-N, and Al increases efficiency a nd reduces cost for soil test laboratories and laboratory users.