ABSTRACT Dry combustion analysis of carbon (C) and nitrogen (N) in materials of biological or mineral origin is safer and less labor-intensive than traditional acid digestion methods, and can give better recoveries of both elements. Dry combustion macro-analyzers have recently been developed, which allow a sample size of up to several grams to be analyzed for C and N, thereby further increasing the precision and accuracy of these determinations. One of these macro-analyzers, the Leco CN-2000 is a dedicated C and N analyzer, and hence, unlike its companion instrument the Leco CNS-2000, can be finely controlled to maximize the recoveries of organic and inorganic C and N. As yet, though, the combustion temperatures and oxygen flow-rates necessary for optimizing the recoveries of C and N from soil have not been determined for this instrument. Two separate combustion conditions (profiles) were therefore sought for the Leco CN-2000, one of which would minimize the decomposition of carbonate C while maximizing t...