Title: Age chronosequence effects on restoration quality of reclaimed coal mine soil in Mississipian agro-ecosystems Authors
|Lang, David -|
|Mcgrew, Rebecca -|
Submitted to: Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 29, 2013
Publication Date: N/A
Interpretive Summary: Surface mining causes drastic disturbances to soil profile and alters soil physical and structural properties. During the past several decades research has shown that surface coal mining negatively impacts physical, chemical, and biological properties of the soil and results in the breaking of soil aggregates and exposure the C fraction to microbial attack. Surface coal mining decreases both soil organic carbon (SOC) and nitrogen (N) pools, disturbs soil structure and reduces the productivity. Reclamation of disturbed coal mine soil is reestablishment of a productive, healthy, and sustainable ecosystem suitable for post-mining land use. In order to understand the sustainability and functioning of an agro-ecosystem in a reclaimed coal mine soil, it is important to characterize and study the quality indicators and how these indicators change and improve with years after reclamation. Several studies have reported the effects of reclamation on improvement of soil physical, chemical and biological properties over time. For example, the results of an age chronosequence study ranging from 5–25 years old in a reclaimed coal mine soil indicated that soil N, P and organic C increased with time. Another study also showed that C and N pools and bulk densities were strongly related with reclamation age, and the rates of ecosystem C and N sequestration peaked at about 10 to 15 years of reclamation. The rate of C sequestration, microbial activity, and nutrient cycling depend on productivity of the forest or grasses established on reclaimed sites and on mine soil quality. The effects of age chronosequence on quality characteristics and the potential of reclaimed mine soil for soil organic C sequestration have been reported mainly in temperate and cold climatic conditions The effect of reclamation age on soil development in southeastern U.S., particularly in Mississippi which has a humid subtropical climate with high precipitation, is challenging and has not been investigated. Therefore, the objective of this study was to evaluate in reclaimed mine sites how soil physical, chemical and biological properties change over time in different land uses and landscape positions under Mississippian agro-ecosystems.
Technical Abstract: Surface coal mining causes drastic disturbances in landscape and soil properties, and reclamation has the potential to improve and re-store soil quality and biomass productivity. However, it is not clear how long it takes for an effective soil reclamation process to restore soil quality to the pre-mined conditions in the southeastern US. The objective of the study was to evaluate age chronosequence effects on restoration quality of reclaimed coal mine soil in different land use and landscape positions under Mississippian agro-ecosystems. Sites were selected with succession (0-3, 5-7, and 10-12 yr old) in reclaimed soils. Adjacent undisturbed sites were also used as a reference. Both bulk and core soil samples were collected at 0-15 and 15-30 cm depth within a grid in a radius of 10 feet, mixed thoroughly to yield one composite sample per grid and kept frozen until analyzed. The bulk density (BD) was the highest in site reclaimed in 2012 (1.48 g cm-3) and reduced with age since reclamation in 2000 (1.07 g cm-3). Soil quality indicators include aggregate stability, total C, organic C, and microbial biomass C increased with increasing reclamation age for both forest and grass covers. The concentration of C fraction levels was greater at the summit compared to shoulder and foot-slope positions. Soil pH, Ca, Mg, Cu, and Zn were higher in newly reclaimed soil than 12 yr since reclamation possibly due to presence of trace carbonate which buffer the pH to >7.0 in newly reclaimed site. In this region, reclamation practices improved soil quality indicators over time, and their magnitudes reached to levels similar to undisturbed soil about 7-12 years since reclamation indicating establishment of a post-mining healthy and sustainable ecosystem in Mississippi.