Biochemistry of nitrification in soil. 1. Kinetics of, and the effects of poisons on, soil nitrification as studied by a soil perfusion technique

[First paragraph] Nitrification is the process whereby nitrogen, in the form of the ammonium cation or in organic combination, is converted into the nitrate anion. Nitrification in soil has long been established as a biological process (Schloessing & Muntz, 1877, 1879), but some evidence that, under tropical conditions, a non-biological nitrification in soil may occur has recently accumulated.