Soil Aggregation and Aggregate‐Associated Organic C and Total N as Affected by Revegetation Pattern at a Surface Mine on the Loess Plateau, China

Abstract

Core IdeasVegetation restoration improves the soil structure and enhances the OC and TN associated with soil aggregates.A greater proportion of microaggregates with higher OC and TN were the main mechanisms for OC and TN accumulation.Planting grasses should be a good option for the reclamation of surface mine areas.Re‐establishing cover of vegetation can improve soil structure and increase organic carbon (OC) and total nitrogen (TN) accumulation in mine sites. In this study, we collected soil samples from reclaimed mine sites (RMSs), which comprised sites revegetated with trees (Tr), bushes (Bu), or grasses (Gr), and from the adjacent undisturbed native sites (UNSs). We evaluated the effects of revegetation patterns on: (i) soil aggregate formation and (ii) the distributions of OC and TN in different aggregate size classes. In the 0‐ to 15‐cm layer, the distribution of the aggregate sizes as well as the OC and TN concentrations in both the bulk soil and aggregate fractions did not differ significantly between the RMSs and UNSs. However, in the 15‐ to 30‐cm layer, the macroaggregate (>0.25 mm) fractions were generally lower and the microaggregate (0.25–0.053 mm) fractions were generally higher in the RMSs than the UNSs. The OC and TN concentrations in both the bulk soil and aggregate fractions were lower in the RMSs than the UNSs. Among the RMS revegetation patterns, Gr had a significantly higher proportion of microaggregates and a significantly lower proportion of the <0.053‐mm size classes than Tr in both layers. The OC and TN concentrations in both the bulk soil and aggregate fractions were significantly higher in Gr than Tr. There were no significant differences between Bu and Gr in terms of either the aggregate size distribution or the OC and TN concentrations. However, planting grasses may be a better choice considering the economic cost.