TY - JOUR
T1 - Determination of Nitrogen by Microdiffusion in Mason Jars
T2 - II. Inorganic Nitrogen-15 in Soil Extracts
AU - Saghir, N. S.
AU - Mungwari, F. P.
AU - Mulvaney, R. L.
AU - Azam, F.
PY - 1993/12/1
Y1 - 1993/12/1
N2 - Simple microdiffusion methods were evaluated for N-isotope analysis of NH4 +, NO3 - and NO2 - in soil extracts. In these methods, the soil extract is treated with MgO or MgO and Devarda's alloy in a 473-mL (1-pint) widemouth Mason jar, the NH3 liberated being collected in a Petri dish containing 3 mL of boric acid-indicator solution, or in an acidified glass-fiber disk, suspended from the Mason-jar lid. To avoid cross-contamination error from retention of 15N, the lid was immersed in 0.05 M KOH for at least 24 h before reuse. Serious error occurred when NO3 --N was diffused following NH4 +-N; therefore, separate diffusions should be performed for NH4 +-N and (NH4 + + NO3 _)-N or (NH4 + + NO3 - +NO2 - )-N. In studies to evaluate the latter approach using labeled soil extracts analyses for 15N were within 2% of the corresponding values calculated by isotope-dilution equations. No interference by alkali-labile organic N was observed in diffusion of 15N-labeled extracts from soil receiving various treatments to increase soluble organic N.
AB - Simple microdiffusion methods were evaluated for N-isotope analysis of NH4 +, NO3 - and NO2 - in soil extracts. In these methods, the soil extract is treated with MgO or MgO and Devarda's alloy in a 473-mL (1-pint) widemouth Mason jar, the NH3 liberated being collected in a Petri dish containing 3 mL of boric acid-indicator solution, or in an acidified glass-fiber disk, suspended from the Mason-jar lid. To avoid cross-contamination error from retention of 15N, the lid was immersed in 0.05 M KOH for at least 24 h before reuse. Serious error occurred when NO3 --N was diffused following NH4 +-N; therefore, separate diffusions should be performed for NH4 +-N and (NH4 + + NO3 _)-N or (NH4 + + NO3 - +NO2 - )-N. In studies to evaluate the latter approach using labeled soil extracts analyses for 15N were within 2% of the corresponding values calculated by isotope-dilution equations. No interference by alkali-labile organic N was observed in diffusion of 15N-labeled extracts from soil receiving various treatments to increase soluble organic N.
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U2 - 10.1080/00103629309368993
DO - 10.1080/00103629309368993
M3 - Article
AN - SCOPUS:0027331755
SN - 0010-3624
VL - 24
SP - 2747
EP - 2763
JO - Communications in Soil Science and Plant Analysis
JF - Communications in Soil Science and Plant Analysis
IS - 19-20
ER -