Abstract:
The evolution of mineral-associated soil organic matter was examined during paddy soil evolution. The Hangzhou Bay (PR China) is characterized by land reclamation of marine sediments and provides a unique setting with soil chronosequences of 50 to 2000 years of paddy soil management and of 50 to 700 years of non-inundated croplands (non-paddy soils). Overall, the results presented in this dissertation demonstrate that organic carbon (OC) accumulates preferentially in the <20 µm fraction. This <20 µm fraction is characterized by a paddy-specific iron (Fe) oxide formation. The OC accumulation due to organo-mineral associations, especially by association with oxalate extractable Fe (Feox), is particularly pronounced during paddy soil evolution. Paddy soils are characterized by markedly higher potential for OC accumulation since the earliest stages of pedogenesis due to higher proportions of Feox than in non-paddy soils.