Simultaneous determination of total C,total N,and 15N on soil and plant material

Abstract

Availability of labor and laboratory instrumentation has frequently limited use of isotopes in N management research. Recent innovations in laboratory instrumentation have made it possible to simultaneously determine total C, total N, and ¹⁵N concentrations in plant, soil, and water samples. An automatic C and N analyzer was interfaced with a continuous‐flow mass spectrometer for purposes of routine analytical determinations. Compared to manual procedures, the automated procedure was rapid, accurate, and gave reproducable results both over time and between adjacent samples. Ball‐mill preparation of samples greatly increased precision of determinations and is recommended to improve sample homogeneity.