Oxygen Uptake and Respiratory Quotient of Field Soil Cores in Relation to Their AIr‐filled Pore Space

Summary The oxygen uptake and respiratory quotient ( RQ ) of field cores from three soils of different texture classes were studied using electrolytic respirometers. Critical values of air‐filled pore space ( f ), above which RQ was always near unity, that is, corresponding to the transition from anaerobic to aerobic respiration, were defined for each soil. These critical values agreed with minimum values off required for plant growth as reported in the literature, suggesting that RQ can be used as an index of adequate soil aeration. Oxygen uptake by the three soils reached a maximum at f values slightly above the critical values, corresponding to the highest moisture content at which oxygen diffusion was non‐limiting.