Microbial Respiration and Organic Carbon Indicate Nutrient Cycling Recovery in Reclaimed Soils

Abstract

ent on a reclaimed area will depend to a large degree on a range of soil physical, chemical, and biological vari-Soil quality and the ability of soil to sustain nutrient cycling in drasables (National Research Council, 1994) and the severe tically disturbed ecosystems will influence the establishment and maintenance of a permanent and stable plant community. We undertook perturbations that occur in the strip mining process can research to evaluate a recently developed method to assess soil quality severely impact these variables. and nutrient cycling potential in a series of reclaimed soils. The method Arid and semiarid soils are characteristically low in involves correlating the 3-d flush of microbial respiration after a soil SOM and nutrients (Jenny, 1930) and this inherently is rewetted against a range of soil biological parameters. Soils were low soil fertility is further reduced by the mining process. sampled from a number of reclaimed coal mines, a reclaimed uranium In this process, the surface layers of soil (typically the mine, and native, undisturbed prairie. All sites were located in semiarid A ϩ B horizons) are removed, potentially stored for a Wyoming. Soils were dried at 55؇C, rewetted, and microbial respiration period of time in large stockpiles where plant inputs are measured at 3 d (Cmin 0-3d ) and 21 d (Cmin 0-21d ). In addition, microbial often minimal (particularly at depth), and then respread biomass C (MBC), N mineralization (Nmin 0-21d ), soil organic C (SOC), over regraded spoil material on these reconstructed sites. and total N were also measured. Correlations between Cmin 0-3d and the measured soil parameters in reclaimed and native soils were generally Soils are further altered, especially physically, during strong (r 2 Ն 0.45) and highly significant (P ϭ 0.0001). Differences seedbed preparation. All of these operations result in the between reclaimed and native soils were observed, with native soils destruction of aggregates (Abdul-Kareem and McRae, exhibiting more variability, possibly due to: differences in soil homog-1984) leading to the rapid mineralization and subseeneity/heterogeneity, the relative lability of the substrates present; quent decline of SOC. This loss of soil C is further exdifferent microbial communities; and differences in soil structural propacerbated by the additional dilution of C and nutrients erties. Correlations between Cmin 0-3d and the measured soil paramwhen the soils are salvaged and respread, as the much eters in spoil material, while significant, were less well correlated. We greater concentration of C and nutrients present in the believe this method is a relatively fast, accurate, and economical means A horizon are mixed with the B horizon. There is little by which soil quality and nutrient cycling can be ascertained. We in the way of literature as to the amount of SOC/SOM estimated that a minimum concentration of 0.52% SOC or 0.89% soil organic matter (SOM) is necessary to sustain an adequate level of

Carbon Dynamics of Reclaimed Coal Mine Soil under Agricultural Use: A Chronosequence Study in the Dongtan Mining Area, Shandong Province, China

“…However, it usually takes more than 20 years to restore a soil's microbial biomass to the level of the original landscape in the semi-arid mining areas in Wyoming, USA [49]. The correlation analysis revealed a highly significant positive correlation between the MBC and the SOC contents (r = 0.737, p < 0.01), which is in agreement with the results of Adeli et al [26] and Ingram et al [50]. This suggests that organic matter is the main energy source for soil microorganisms; the organic carbon added to reclaimed soils during agricultural activities is rapidly utilized by microbial communities, which contributes to the rapid increase in the soil's MBC content and the restoration of a damaged ecosystem.…”

The Influence of Management Practices on Microbial and Total Soil Nitrogen

“…We observed that though microbes from undisturbed soils contained less N than microbes from reclaimed communities, they took up N at a greater rate. This would seem to support a hypothesis that we put forward previously (Ingram et al, 2005) in which we suggested that there is a greater supply of labile material present in reclaimed soils despite lower overall concentrations of TN. In contrast, undisturbed soils have a greater mass of TN, but much of it is present in more humified soil organic matter (SOM) fractions, and this N is less available for microbial uptake.…”

“…The results of our current work though give rise to somewhat of a conundrum, in that TN is almost always lower in reclaimed soils (approximately 30% lower) but most of the time plant productivity is greater (74% of reclaimed sites averaged 77% greater production relative to undisturbed sites; Ingram et al, 2005 andL. Ingram, unpublished data, 2006).…”

“…We have previously observed a strong relationship between TN and Nmineralization in reclaimed soils (P = 0.0001, r 2 = 0.70, n = 275; L. Ingram, unpublished data) and thus in soils which average 1 / 3 less TN, it seems unlikely that N-mineralization would be greater in reclaimed soils. In addition, though N-mineralization is often greater in reclaimed relative to undisturbed soils, it is not an across the board phenomena (Ingram et al, 2005). …”

Soil‐Test Biological Activity with the Flush of CO2: I. C and N Characteristics of Soils in Corn Production

“…From 4 yr of sampling at four soil depths in a long-term integrated croplivestock trial on Typic Kanhapludults in Georgia, the association between net N mineralization during 24 d and the flush of CO 2 in 3 d was very strong (r 2 = 0.82; n = 646) (Franzluebbers and Stuedemann, 2008). From a range of reclaimed mine spoils and native grasslands in Wyoming, the association between net N mineralization during 21 d and the flush of CO 2 in 3 d was also strong (r 2 = 0.72; n = 22; Ingram et al, 2005). From Typic Kanhapludults in North Carolina, strong association of net N mineralization during 24 d with the flush of CO 2 in 3 d was observed, but with a plateau effect occurring when the flush of CO 2 exceeded 500 mg kg -1 (r 2 = 0.72; n = 120; Franzluebbers and Brock, 2007).…”