Subramanian, S., A. Kravchenko, X. Hao
Presented at the ASM at Estes Park (2006-09-01 to 2012-09-23 )
The ability to sequester carbon in the soil is influenced by many factors i.e., management practices, topographical factors and inherent soil properties. Among the factors influencing magnitude and direction of long-term management effects are soil C levels prior to management implementation. We assume that the sequestration rate will be higher in the soil with low initial carbon than in the soil with high initial carbon. The objective of this study is to analyze the relationship between initial carbon content and the soil carbon sequestration potential under different crop management practices 18 years after experiment implementation. We compared three management systems, namely, chisel plowed tillage (CT) and no-till with conventional chemical inputs (NT), and a certified organic chisel plowed system with a winter leguminous cover crop and zero chemical inputs (CT+cover) from a Long Term Ecological Research (LTER) site located at Kellogg Biological Station, southwest Michigan, established in 1988. A set of 417 total C measurements obtained from the experimental site in 1987 prior to the experiment establishment serves as a baseline data in this study. In 2006, using GPS we identified 50 of the 1988 sampling sites that were located well within the boundaries of CT, CT+Cover crop and NT treatment plots and carried out soil sampling using hydraulic soil core unit. The data were first analyzed using separate regressions for each treatment with initial C as an independent variable and the change in C values from 1988 to 2006 as a dependant variable and then, the interaction effect between initial carbon and different management systems were studied using ANCOVA. Effects of treatments and initial carbon levels on total C gains and losses will be presented and discussed.
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