The sequestration and release of carbon in soil is a crucial aspect of agricultural production studies, involving numerous small-plot trials and modelling processes. Small-scale heterogeneity in soil properties can influence measured carbon dioxide (CO2) fluxes. This study aimed (i) to compare CO2 emission from two neighbouring sandy soil plots managed with identical agricultural practices; (ii) to identify the key factors influencing soil CO2 emissions; and (iii) to examine the effect of soil water content (SWC) and soil temperature (Ts) on the results. Two plots located approximately 30 m apart and differing in terms of their humus depths and contents were selected for investigation. Continuous SWC and Ts measurements were taken. Portable devices were used to determine CO2 emissions, penetration resistance (PR) and vegetation cover. The humus layer in plot A was 55 cm thicker than in plot B, while the soil organic carbon (SOC) content was 18% and 163% higher in the 0–30 cm and 30–90 cm soil layers, respectively. Vegetation cover was nearly twice as high in plot A, and the mean soil CO2 emissions were 36% higher than those measured in plot B. SWC showed an opposite trend, with plot B exhibiting values that were 9.7% and 17.7% higher than those of plot A in both the top and deepest soil layers, respectively. These findings emphasize the importance of including small-scale spatial heterogeneity when parameterizing or interpreting biogeochemical models, particularly when model inputs are based on limited soil measurements from specific locations.
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