Fig. 2. Example section of Fourier-transform infrared spectroscopy (FT-IR) absorption spectrum of an air sample during laboratory scale composting of hay (mixed herbage from landscape conservation with a moisture content (w.b.) of 0.7 x 10–3 m3 kg–1) amended with calcium ammonium nitrate (resolution 0.2 cm–1, temperature 35°C, aeration rate 17 cm3 min–1 kg–1 substrate). Circled numbers indicate sections analyzed in detail: 1: Superposition of CO2, N2O, and CO; 2: Mainly CO lines; 3: Mainly CO2 lines; 4: Minimally disturbed CO lines.