ABSTRACT
This chapter examines the relationship between the function of various organomineral associations as aggregate binding agents and carbon (C) sequestration in soils. It analyses soils that exhibit an aggregate hierarchy in which aggregate stability is controlled primarily by organic materials. The chapter explores the nature and function of organomineral associations in macro- and microaggregates. It presents evidence from studies of restored prairies on Illinois mollisols as a case study to demonstrate the occurrence of feedbacks between aggregation and C accrual in an aggrading system. Golchin et al. proposed a conceptual model of the changes organic matter undergoes during decomposition, from its entry into the soil through its incorporation into microaggregates to its eventual rendering into microbial metabolites and association with clay minerals. The nature of various organomineral associations and their spatial locations within soil aggregate structure determine the extent to which soil organic carbon is physically protected and chemically stabilized, resulting in organic pools with varying input and turnover rates.
