Carbon Dynamics under Long‐Term Conservation and Disk Tillage Management in a Norfolk Loamy Sand

Soil organic carbon (SOC) sequestration is an important process to mitigate CO 2 emissions. Our objectives were to determine the rates of C sequestration and to determine if the SOC pool was at or approaching equilibrium in plots under long‐term (24‐yr) conservation (CT) and disk tillage (DT) management. The plots were Norfolk loamy sand (fine‐loamy, kaolinitic, thermic, Typic Kandiudult) and were under a row crop rotation. All plots received annual subsoiling, while only plots under DT were surface disked. Soil cores were collected to 90 cm deep. After 24 yr, the only significant increase in SOC occurred in CT plots at a 0‐ to 5‐cm depth. The SOC pool in plots under DT was at a near‐steady state, while the SOC pool under CT was not at equilibrium. This supports the conclusion that CT is an effective countermeasure to offset atmospheric CO 2 emissions.