Conant, Richard (Colorado State University, Natural Resource Ecology Laboratory, Campus Delive, Fort Collins, CO, 80523-1499; Phone: 970-491-1919; Fax: 970-491-1965; Email: conant@nrel.colostate.edu)

Disturbance and Recovery of Soil C Following Infrequent Activities

R.T. Conant *, A. Swan, K. Paustian

Short-term studies indicate that substantial amounts of C can be lost from the soil immediately following a tillage event. What are the implications for producers who have adopted no-tillage, but feel that they must till to control weeds or relieve compaction? How much of the C that has been sequestered is lost? What are the longer-term impacts of continued infrequent no-tillage? Conversely, how does integrating a periodic ley period into a rotation? How is C impacted by tillage in this type of rotation? A few studies have examined the impact of occasional tillage on soil C, but results are contradictory. If producers are to be compensated for sequestering C in soil, the impacts of infrequent tillage should be documented so that contracts can account for this. We present (1) a review the literature examining the short-term impacts of tillage on soil C, (2) review published studies documenting impacts of infrequent tillage in predominantly no-till systems, (3) an assessment of the impacts of ley rotations on recovery of soil C, and (4) results from a modeling study carried out to address these questions more broadly than the published literature allows.