Physico-chemical and Bio-chemical Controls on Soil C Saturation Behavior
- Univ. of California, Davis, CA (United States)
- Univ. of Pennsylvania, Philadelphia, PA (United States)
In this project, we tested through a multitude of lab and field experiments the concept of soil C stabilization and determined metrics for the level of C saturation across soils and soil organic matter fractions. The basic premise of the soil C saturation concept is that there is a maximum amount of C that can be stabilized within a soil, even when C input is further increased. In a first analysis, our results showed that linear regression models do not adequately predict maximal organic C stabilization by fine soil particles. Soil physical and chemical properties associated with soil clay mineralogy, such as specific surface area and organic C loading, should be incorporated into models for predicting maximal organic C stabilization. In a second analysis, we found significantly greater maximal C stabilization in the microaggregate-protected versus the non-microaggregate protected mineral fractions, which provides independent validation that microaggregation plays an important role in increasing the protection and stabilization of soil C leading to greater total soil C accumulation in these pools. In a third study, our results question the role of biochemical preference in mineral C stabilization and of the chemical recalcitrance of specific plant-derived compounds in non-protected soil C accumulation. Because C biochemical composition of slowly turning over mineral protected C pools does not change with C saturation, input C composition is unlikely to affect long-term C stabilization. Rather, C saturation and stabilization in soil is controlled only by the quantity of C input to the soil and the physical and chemical protection mechanisms at play in long-term C stabilization. In conclusion, we have further corroborated the concept of soil C saturation and elucidated several mechanisms underlying this soil C saturation.
- Research Organization:
- Univ. of California, Davis, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER)
- DOE Contract Number:
- FG02-04ER63912
- OSTI ID:
- 1015558
- Report Number(s):
- DOE/ER-63912
- Country of Publication:
- United States
- Language:
- English
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