IntroductionCarbon sequestration is one of the major strategies for removing atmospheric carbon dioxide (CO2) and fixing it in the soil and plants.MethodsThis study focused on the carbon sequestration and greenhouse gas dynamics of three different forage sorghum cultivars: Sugar Graze Ultra (annual), PSH20TX01 (perennial seeded), and PSH09TX15 (perennial rhizomes), in Southern Texas, USA, where each cultivar had nine experimental plots. The field experiment was conducted over two growing seasons, in 2024 and 2025, at the Prairie View A&M University research farm. Three fertilizer rates (Recommended, half-recommended, and zero) were applied. Soil greenhouse gas emissions were measured weekly on each plot using a trace gas analyzer throughout the growing seasons. Both soil-disturbed and soil-intact core samples were collected from depths of 0–15 cm (surface) and 15–45 cm (subsurface) before and after planting season 1, and after harvesting season 2. Above-ground and below-ground biomass were collected from a 2 ft × 2ft area at each end of the season. From the collected soil samples, soil bulk density, total soil carbon percentage, soil pH, and soil electrical conductivity were analyzed. Soil carbon stock, total plant carbon stock, total below-ground carbon stock, and total ecosystem carbon stock were calculated from the biomass and soil data.Results and DiscussionStatistical analysis using ANOVA revealed that the bulk density in the soils of PSH09TX15 was significantly lower than that in the Sugar Graze Ultra soils at both depths at the end of season 2. Although there was no significant difference in soil total carbon among varieties in season 2 in the surface, subsurface total carbon was significantly higher in PSH20TX01. Significantly higher above-ground biomass was recorded in the Sugar Graze Ultra, and significantly higher below-ground biomass was observed in the PSH09TX15 cultivar. Total ecosystem carbon storage was highest in the Sugar Graze Ultra Sorghum variety (18.98 Mg C/ha). However, PSH09TX15 showed the highest below-ground carbon stock (11.01 Mg C/ha), which directly influences the long-term soil carbon sequestration. Lower CO2 emissions were recorded in the soils of PSH09TX15. The research provides insights into the carbon sequestration capabilities of three forage sorghum varieties, highlighting their potential to mitigate climate change.