Physico-chemical and Bio-chemical Controls on Soil C Saturation Behavior

Six, Johan¹  Plante, Alain F.² 

[1] Univ. of California, Davis, CA (United States);Univ. of Pennsylvania, Philadelphia, PA (United States)

关键词: carbon sequestration;   

DOI  :  10.2172/1015558
RP-ID  :  DOE/ER--63912
PID  :  OSTI ID: 1015558

学科分类：环境科学（综合）

美国|英语

来源: SciTech Connect

【 摘 要 】

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.