PARENT SESSION
Poster Session #42: Carbon Storage.
Thursday, August 9, 2001. Presentation from 3:30 PM to 5:00 PM. Exhibition Hall

Effect of tillage and carbon input levels on soil organic carbon distribution.

HOOKER, BETH¹, CARDON, ZOE¹, ¹

ABSTRACT- A current focus of research aimed at reducing atmospheric CO2 is the role of cropland in sequestering C. Unfortunately, our present understanding of the mechanisms which control whether crop residue is retained in soil C pools, or released as atmosphere CO2 is deficient. We have conducted research on the carbon dynamics of a corn field at the UConn Research Farm, where plots have been under no-till or conventional till management, with silage corn (no shoot residue after harvest) or grain corn (shoot residue remains after harvest), with three replicates, since 1969. These plots are unique to long-term agricultural experiments because we have both tillage differences and differential C input practices in place. Soil data show significant differences in d13C and %C values between grain and silage plots, and between conventional and no-till management. As expected, conventional tilling, causing enhanced decomposition of labile carbon residues, resulted in decreased proportion of C4 organic matter being retained in whole soil and decreased %C relative to no-till. The silage treatment (aboveground organic matter removed) also resulted in a decreased proportion of C4 organic matter contributing to soil carbon, and decreased %C relative to the grain treatment. This is consistent with our expectation that the no-till system would sequester C more effectively and that increased C inputs over a long time from the grain plots increase this effect. We are currently evaluating soil C allocation.

KEY WORDS: carbon, conservation tillage, carbon sequestration