Nonsustainable agricultural practices often lead to soil carbon loss and increased soil carbon dioxide (CO₂) emissions into the atmosphere. A research study was conducted on arable fields in central lowland Croatia to measure soil respiration, its seasonal variability, and its response to agricultural practices. Soil C-CO₂ emissions were measured with the in situ static chamber method during corn (Zea mays L.) and winter wheat (Triticum aestivum L.) growing seasons (2012 and 2013, n = 288) in a field experiment with six different tillage treatments. During corn and winter wheat growing season, average monthly soil C-CO₂ emissions ranged, respectively, from 6.2–33.6 and 22.1–36.2 kg ha⁻¹ day⁻¹, and were decreasing, respectively, from summer > spring > autumn and summer > autumn > spring. The same tillage treatments except for black fallow differed significantly between studied years (crops) regarding soil CO₂ emissions. Significant differences in soil C-CO₂ emissions between different tillage treatments with crop presence were recorded during corn but not during winter wheat growing season. In these studied agroecological conditions, optimal tillage treatment regarding emitted C-CO₂ is plowing to 25 cm along the slope, but it should be noted that CO₂ emissions involve a complex interaction of several factors; thus, focusing on one factor, i.e., tillage, may result in a lack of consistency across studies.