In addition to improving sustainability in cropping systems, the use of a spring and winter crop rotation system may be a viable option for mitigating soil CO 2 emissions (ECO 2 ). This study aimed to determine short-term ECO 2 as affected by crop rotations and soil management over one soybean cycle in two no-till experiments, and to assess the soybean yields with the lowest ECO 2 . Two experiments were carried out in fall-winter as follows: i) triticale and sunflower were grown in Typic Rhodudalf (TR), and ii) ruzigrass, grain sorghum, and ruzigrass + grain sorghum were grown in Rhodic Hapludox (RH). In the spring, pearl millet, sunn hemp, and forage sorghum were grown in both experiments. In addition, in TR a fallow treatment was also applied in the spring. Soybean was grown every year in the summer, and ECO 2 were recorded during the growing period. The average ECO 2 was 0.58 and 0.84 g m 2 h −1 with accumulated ECO 2 of 5,268and 7,813 kg ha -1 C-CO 2 in TR and RH, respectively. Sunn hemp, when compared to pearl millet, resulted in lower ECO 2 by up to 12 % and an increase in soybean yield of 9% in TR. In RH, under the winter crop Ruzigrazz+Sorghum, ECO 2 were lower by 17%, although with the same soybean yield. Soil moisture and N content of crop residues are the main drivers of ECO 2 and soil clay content seems to play an important role in ECO 2 that is worthy of further studies. In conclusion, sunn hemp in crop rotation may be utilized to mitigate ECO 2 and improve soybean yield.