Rapid Assessment of Carbon Sequestration In Southern Plains No-till Management.

A study was initiated to evaluate the organic carbon sequestration potential of no-till management of agricultural soils in the Southern Plains region of Oklahoma. This project involved the sampling of more than 40 paired cropland fields. The paired field sample locations were similar in soil type and landscape position, with one field in the pair being cultivated and the other being under no-till management. Samples were collected to a depth of 110 cm with a hydraulic soil probe. These cores were sectioned into depth increments of 0-10, 10-20, 20-40, and 40-70cm and analyzed for organic carbon and bulk density. These values were used to calculate the mass of carbon per ha to each depth. The mass of carbon found in no-till fields to a depth of 10 cm was significantly greater (p<0.1) than that found in the cultivated fields. However, there were no significant differences when the carbon mass below this depth was included in the analysis. This of course is at least in part the result of the dilution effect that increasing the depth of sampling has on assessing small changes in soil carbon mass. Long-term monitoring of these sites will be required for proper evaluation of the impact of tillage on subsoil carbon.