A research study on agricultural ecosystem in Isabela was conducted to generate indicative estimate of carbon storage capacity of major crop species. It aimed to determine the stored carbon in biomass of sweet sorghum (Sorghum bicolor (L.) Moench), sugarcane (Saccharum officinarum L.) and yellow corn (Zea mays L.). The result of the study shows that sugarcane has the highest biomass or dry matter of 522.46 grams per cane followed by corn with 237.75 grams and sorghum with 66.34 grams. Total aboveground dry matter was estimated at 21.22 ton/ha for sugarcane, 12.42 ton/ha for corn and 7.89 ton/ha for sorghum. The three species showed contrasting carbon storage capacities per hectare. Sorghum stores about 3.95 t C/ha; corn stores about 6.21 t C/ha; and sugarcane stores about 10.6 t C/ha. Among the three plant species studied, sugarcane was the most stable for carbon storage. The study also revealed that sugarcane sequesters the greatest amount of CO2 per hectare, which is approximately 39.26 t/ha compared to sorghum or corn, which sequester only about 16.63 t/ha and 22.97 t/ha, respectively. This suggests that sugarcane absorbs or assimilates more CO2 from the air than either sorghum or corn. The three species however, are potential carbon sinks because they remove carbon dioxide from the atmosphere and store it into biomass in the process of photosynthesis.