Effects of the Stability of Reclaimed Soil Aggregates on Organic Carbon in Coal Mining Subsidence Areas

Abstract. Reclaimed soil aggregates play a critical role in the accumulation of soil organic carbon. The purpose of this article is to investigate the effects of reclaimed soil aggregate development on organic carbon and explore changes in reclaimed agricultural soil over time in a coal mining subsidence area. Adjacent to the control sample plot (CKN), six sample plots of different reclamation time series: 2001 (R15), 2003 (R13), 2005 (R11), 2007 (R9), 2009 (R7), and 2011 (R5) were collected. Soil analyses included aggregate fractionation and organic carbon. Over time, the distribution characteristics of water-stable aggregates in reclaimed soil gradually improved. The concentration of organic carbon in reclaimed soil increased with aggregate size, and the organic carbon concentration of all aggregates increased with reclamation age. As the number of reclamation years increased, organic carbon also increased, first in the free light fraction (fLF) and later in mineral-bound carbon (mineral-C). Accumulation of organic carbon was related to the development of soil aggregates. The formation and carbon sequestration of reclaimed soil aggregates was consistent with the conceptual model of “aggregate turnover.” The transformation and accumulation of organic carbon was consistent with the physical protection mechanism of soil organic carbon. Keywords: Aggregate, Coal mining subsidence area, Reclaimed soil, Soil organic carbon.