Soil pore space CO2, O2, and apparent respiratory quotient (ARQ) data collected from experimental soil wetting experiments

Soil pore space CO2, O2, and apparent respiratory quotient (ARQ) data are from experimental soil wetting experiments. These laboratory wetting experiments were designed to test how calcite dissolution and precipitation can obscure the CO2 produced by soil respiration in response to rainfall events. Natural soil samples were collected from the University of Texas Stengl Lost Pines Biological Station (Latitude: 30.096°; Longitude -97.171°, Elevation: 145 m a.s.l.). Collected soil was sieved and filled to 25 cm depth into two separate tubs (49 cm long x 34 cm wide x 29 cm high) in the laboratory. Approximately 20 weight percent calcite was mixed into the treatment soil, and the other soil was left untreated. Soil gas samples were collected every four hours from a perforated horizontal gas well installed at 20 cm depth using an automated manifold system. Soil gas samples were dried and then the O2 and CO2 concentrations were measured using a Sable Systems (Las Vegas, Nevada, USA) Field Metabolic System. Temperature drift in the raw O2 data was corrected for by normalizing ambient air O2 measurements to 20.95%. W ARQ values were calculated as the relative difference in soil gas concentrations between the soil and ambient air corrected by a constant that accounts for faster diffusion of O2 through soil pore spaces (ARQ = -0.76*ΔCO2/ΔO2). Rain events were simulated by adding the equivalent of 2 cm and 1 cm of water at the beginning of the experiment and 9 days later