Soil respiration on field mesocosms 2022

Soil respiration rates were meticulously assessed on two separate occasions: July 19 and September 20, 2022. These rates were quantified by capturing the flux of CO2 emanating from the soil surface, utilizing the widely recognized Closed Dynamic Chamber method. The methodology employed an Li-8100A field respirometer from Li-Cor Biosciences, USA, in conjunction with polypropylene rings that featured an internal diameter of 105 mm. These rings were embedded into the soil of the mesocosms at a depth of 3 cm to ensure a consistent measurement environment. Concurrent with the respiration rate determinations, soil temperature readings were taken using a precise soil thermometer, part of the respirometer's assembly, capable of 0.1°C resolution. This thermometer, an Omega 88311E model from OMEGA Engineering, UK, provided high accuracy in monitoring the thermal state of the soil. Additionally, soil volumetric moisture content was accurately gauged to within 0.1% using a ThetaProbe ML2 sensor from Delta-T Devices, UK, which was interfaced with the respirometer's control unit for seamless data integration.To ensure a comprehensive understanding of the environmental conditions, both soil humidity and temperature were recorded at the same 5 cm depth as the respiration measurements. Furthermore, air temperature was also tracked, thanks to a built-in sensor in the respirometer's chamber, to account for atmospheric influences on the soil's respiratory activity. The timing of the measurements was carefully selected to reflect typical daytime conditions, consistently conducted between 10 a.m. and 4 p.m. This scheduling minimized variations in diurnal temperature and light that could potentially influence the respiration readings. Experimental design was structured to facilitate robust data analysis, with mesocosms arranged in clusters of eight replicates. These clusters were further organized into three lines, consisting of five clusters each, to standardize the spatial distribution of the measurement points. On the latter date of September 20, additional comparative data was collected from the surrounding meadows adjacent to the experimental site. Eight background soil respiration measurements were conducted to provide a baseline for the experimental readings. To minimize any potential systematic bias due to the natural daily fluctuations of soil and air temperatures, the order in which the mesocosms were measured was deliberately varied between the two dates. This careful randomization ensured that the temporal dynamics did not skew the results, thereby enhancing the reliability of the study's findings.