Author(s)

Ippei Iiyama

School of Agriculture, Utsunomiya University, Mine 350, Utsunomiya, Japan.

Soil is a large terrestrial carbon pool so that the evaluation and prediction of soil respiration is important for understanding and managing carbon cycling between the pedosphere and the atmosphere. For better understanding about characteristics and mechanisms of soil respiration, this study monitored seasonal behaviors of soil gaseous CO₂ concentration profile with relevant soil physical conditions in a meadow field, and numerically analyzed the monitored data sets to inversely determine time-series of depth distributions of CO₂ production rate in the field by assuming optimum ranges of depth and moisture condition for aerobic respiration of soil fauna and flora. The results of the inverse analyses showed that the depth range of intense CO₂ production resided in top soil layers during summer and moved down into subsoil layers in winter, implying that the depth range of main CO₂ sources can change dynamically with seasons. The surface CO₂ emission rates derived from the inverse analyses fell in the range typically found in the same kind of land use. The evaluated mean residence time of gaseous CO₂ in the study field was around half a day. These findings suggested that the modelling assumptions about soil respiration in this study are effective to probe spatial and temporal behavior of respiratory activity in a soil layer, and it is still important to integrate facts about in-situ CO₂ concentration profiles with soil physical parameters for quantitatively predicting possible behaviors of soil respiration in response to hypothetical changes in atmospheric and soil climates.

Gas Diffusion Coefficient, Mass Balance Equation, Soil Temperature, Volcanic Ash Soil, Water Content

Iiyama, I. (2023) Seasonal Change in CO2 Production Rate along Depth in a Grassland Field. Journal of Geoscience and Environment Protection, 11, 106-124. doi: 10.4236/gep.2023.116008.