soil organic carbon stock for reclaimed minesoils in northeastern ohio

land degradation & development

Land Degrad. Develop. 16: 377–386 (2005)

Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/ldr.669

SOIL ORGANIC CARBON STOCK FOR RECLAIMED MINESOILS INNORTHEASTERN OHIO

M. K. SHUKLA* AND R. LAL

Carbon Management and Sequestration Center, School of Natural Resources, FAES, The Ohio State University, Ohio, USA

Received 7 June 2004; Revised 19 October 2004; Accepted 26 October 2004

ABSTRACT

Reclamation of disturbed soils is done with the primary objective of restoring the land for agronomic or forestry land use.Reclamation followed by sustainable management can restore the depleted soil organic carbon (SOC) stock over time. Thisstudy was designed to assess SOC stocks of reclaimed and undisturbed minesoils under different cropping systems in DoverTownship, Tuscarawas County, Ohio (40�32�330 N and 81�33�860 W). Prior to reclamation, the soil was classified as BethesdaSoil Series (loamy-skeletal, mixed, acid, mesic Typic Udorthent). The reclaimed and unmined sites were located side by sideand were under forage (fescue—Festuca arundinacea Schreb. and alfa grass—Stipa tenacissima L.), and corn (Zea mays L.)—soybean (Glycine max (L.) Merr.) rotation. All fields were chisel plowed annually except unmined forage, and fertilized onlywhen planted to corn. The manure was mostly applied on unmined fields planted to corn, and reclaimed fields planted to forageand corn. The variability in soil properties (i.e., soil bulk density, pH and soil organic carbon stock) ranged from moderate tolow across all land uses in both reclaimed and unmined fields for 0–10 and 10–20 cm depths. The soil nitrogen stock rangedfrom low to moderate for unmined fields and moderate to high in some reclaimed fields. Soil pH was always less than 6�7 inboth reclaimed and unmined fields. The mean soil bulk density was consistently lower in unmined (1�27 mg m�3 and1�22 mg m�3) than reclaimed fields (1�39 mg m�3 and 1�34 mg m�3) planted to forage and corn, respectively. The SOC and totalnitrogen (TN) concentrations were higher for reclaimed forage (33�30 g kg�1; 3�23 g kg�1) and cornfields (21�22 g kg�1;3�66 g kg�1) than unmined forage (17�47 g kg�1; 1�98 g kg�1) and cornfield (17�70 g kg�1; 2�76 g kg�1). The SOC stocks inunmined soils did not differ among forage, corn or soybean fields but did so in reclaimed soils for 0–10 cm depth. The SOCstock for reclaimed forage (39�6 mg ha�1 for 0–10 cm and 28�6 mg ha�1 for 10–20 cm depths) and cornfields (28�3 mg ha�1;32�2 mg ha�1) were higher than that for the unmined forage (22�7 mg ha�1; 17�6 mg ha�1) and corn (21�5 mg ha�1;26�8 mg ha�1) fields for both depths. These results showed that the manure application increased SOC stocks in soil. Overallthis study showed that if the reclamation is done properly, there is a large potential for SOC sequestration in reclaimed soils.Copyright # 2005 John Wiley & Sons, Ltd.

key words: reclamation; mining; soil organic carbon; total nitrogen; soil bulk density; C-sequestration; manure

INTRODUCTION

From 1800 to about 1948, most of Ohio’s coal was mined underground. Coal was mined by hand with the help of

animals for most of the 19th century. The first surface mining operation in Ohio was done in a ravine near

Tallmadge, Summit County, in 1810 and the coal exposed along hillsides was removed using picks and shovels or

horse-drawn scrapers. Only the easily recoverable coal was excavated and the depth of excavation was around 10

feet (3 m). For deeper depths, the coal was mined by underground methods. With the development of larger and

more efficient surface-mining equipment, such as the Mountaineer shovel and the Big Muskie dragline, and

improved methods of transportation, such as conveyors and 20- and 40-ton trucks, surface mining of coal grew up

tremendously (Crowell, 1995).

Copyright # 2005 John Wiley & Sons, Ltd.

�Correspondence to: Dr M. K. Shukla, School of Natural Resources, FAES, The Ohio State University, Columbus, Ohio 43210-1085, USA.E-mail: [email protected]

Prior to 1970, the areas under surface mining were delineated on soil maps and identified as a ‘mine dump’ or

‘strip mine’. After the completion of 1970 soil survey, the mine lands were identified as ‘Orthents’ and reclamation

of the mined lands by grading and topsoil application was not required (Indorante and Jansen, 1984). After the

1977 SMCRA (surface mining control and reclamation act), the mined sites were reclaimed back to their original

topography as close to as possible by grading and topsoil application (Shukla et al., 2004a). The mining history in

Ohio reveals that 14 400 ha of land were surface mined between 1914 and 1946 and an additional 3600 ha were

mined between 1947 and 1948. The total mined area up to and including 1972 was estimated at 147 680 to

179 812 ha. Since 1972, an additional 142 106 ha has been mined. Therefore, the total mined area in Ohio ranges

from 289 786 to 321 918 ha (AMLSF, 2000).

Surface mining causes drastic disturbances to soil profile and alters soil physical and structural properties.

Constructed or reclaimed minesoils may exhibit physical conditions drastically altered by anthropogenic

perturbations rather than natural soil-forming processes (McSweeney and Jansen, 1984). The material-handling

operations for restoration (e.g., land forming, spreading topsoil, mulching, etc.) can exacerbate soil compaction

and alter physical and structural characteristics, which may restrict root development.

The soil organic carbon (SOC) stock is a function of tillage practices, and generally decreases with increasing

tillage intensity. In accord, conversion from plow tillage to minimum tillage, conservation tillage or no-till

increases SOC stock (Rasmussen et al., 1998; Shukla and Lal, 2004; Shukla et al., 2003a). The conventional tillage

reduces SOC stock by: (1) exposure of the soil organic matter to the oxidation process and its emission as CO2; (2)

decomposition of crop residues into CO2; (3) disruption of aggregates and exposure of physically protected SOC to

microbial and enzyme activity; and (4) leaching of soluble SOC and associated carbonates into soil profile.

The loss of SOC stock, which adversely affects sustainability of an agronomic/forestry production system, is a

function of climate, terrain, land use and management (VandenBygaart et al., 2002; Shukla et al., 2003a).

Restoration of disturbed minesoil can improve soil quality, biomass productivity, SOC concentration, and C

sequestration (Lal et al., 1998; Shukla et al., 2003b). Few studies have been undertaken on the potential of

reclaimed minesoils for SOC sequestration by comparing them with the undisturbed soil. Akala and Lal (2001),

Underwood and Smeck (2002) and Shukla et al. (2003b) reported a two-fold increase in SOC pools 20 years after

topsoil application in some reclaimed minesoils in Ohio. Most of these data are for soils under pasture or forest,

where soil was not disturbed by tillage operations after reclamation. There are few data on SOC sequestration in

reclaimed minesoils under corn–soybean rotation and tillage systems in Ohio. In order to find out the sustainability

of a land-use system for a given reclaimed field, it is important to study the SOC sequestration potential of

reclaimed minesoils under different land-use and management systems. Therefore, the objectives of this study

were to evaluate: (1) the effects of minesoil reclamation on SOC stock for an arable land use; and (2) interaction

between land use and cropping systems on SOC stock.

MATERIALS AND METHODS

The experimental site is located in Dover Township, Tuscarawas County of Ohio (40�32�330 N and 81�33�860 W;

Figure 1). The Tuscarawas County is in the unglaciated part of Allegheny Plateau. The soil at the reclamation site

was classified as Bethesda soil series (loamy-skeletal, mixed, acid, mesic Typic Udorthent) formed in residuum

and colluvium derived from siltstone, shale, sandstone, and limestone that was graded during surface mining for

coal. The average annual precipitation for Tuscarawas County, Ohio, is 965 mm and average annual summer

(June–August) air temperature is 21�C, and average winter (December–March) temperature �3�C (USDA-ARS,

1986). The study area was surface mined in 1990–1991 and coal was removed from the underlying soil layers. The

reclamation was done according to the Ohio Minesoil Reclamation Act of 1972, which preceded the 1977 SMCRA

Federal Law. The soil was excavated up to the overburden and piled on the adjacent fields. The mining operations

were done until all the recoverable coal was removed from the area. The mined area was reclaimed in 1992 back to

its original topography by grading the spoil and overburden materials and then spreading the stored topsoil on top

of the graded spoil. The entire area was compacted using heavy machinery and was seeded to forage grass

(fescue—Festuca arundinacea Schreb.) and fertilized immediately after reclamation. The entire reclaimed site

378 M. K. SHUKLA AND R. LAL

Copyright # 2005 John Wiley & Sons, Ltd. LAND DEGRADATION & DEVELOPMENT, 16: 377–386 (2005)

remained under forage cover for the next five years. In 1998, about 70 per cent of the reclaimed area under

investigation was planted to corn and soybean.

The three reclaimed and three unmined fields were located side by side and were planted to forage (mixture of

fescue—Festuca arundinacea Schreb. and alfa grass—Stipa tenacissima L.), corn (Zea mays L.) and soybean

(Glycine max (L.) Merr.) (6 fields� 3 treatments). Tillage operations were not performed on unmined fields

planted to forage. The unmined fields under corn–soybean rotation and all three reclaimed fields were chiseled to

about 20 cm depth in March 2002. The reclaimed field planted to soybean was also moldboard plowed up to 25 cm

depth in April 2002. All fields planted to corn received fertilizer at the rate of 112 kg ha�1 of nitrogen. Cow manure

was mostly applied to reclaimed fields at the rate of 10–12 mg ha�1.

Six plots, each 2 m� 0�8 m (or 2 m� 2 corn rows), were demarcated in each of the six fields and a total of 12

bulk and core soil samples were obtained from the 0–10 cm and 10–20 cm depths for each field during October

2002 (6 fields� 6 plots/replications� 2 depths). The soil bulk density (�b) was measured by the core method

(Blake and Hartge, 1986). Total carbon (TC) and total nitrogen (TN) concentrations were determined by the dry

combustion method (Elementar, GmbH, Hanau, Germany). The carbonate content, as determined using 0�2N HCl

solution, was not detectable (no effervescence) in the 0–20 cm soil layer and it was assumed that TC was equal to

SOC. The SOC and TN stocks were calculated by multiplying �b and depth of soil layer with TC or TN.

Statistical Analysis

The descriptive statistics (mean, median, standard error, coefficient of variation, skewness, minimum and

maximum value) for �b, pH, and SOC and TN stocks were obtained by using Statistical Analysis System (SAS

Institute, 1989). The variability of a soil property was considered low when the coefficient of variation (CV) was

< 0�15; moderate between 0�15 and 0�35, and high for CV> 0�35 (Wilding, 1985). The analysis of means was

done for the SOC and TN concentrations and stocks, �b and pH for treatment� cropping system interactions in

both unmined and reclaimed fields separately using SAS Institute (1989). The Duncan’s multiple range test was

used for the mean comparison of soil physical and chemical properties at a significance level of 0�05.

Figure 1. The schematic location of the Ohio (OH) experimental sites (not to the scale). The Tuscarawas County is shown by an asterisk.

SOC STOCKS FOR RECLAIMED SOILS 379


RESULTS AND DISCUSSION

Variation of Soil Properties

The mean and median of soil properties were used as primary estimates of central tendency, and standard

deviation, CV, skewness, minimum and maximum values were used as the estimates of variability (Tables I–IV).

Despite some skewness of distribution of soil properties, the mean and median values were similar, with the

median either equal to or smaller than the mean for soil properties under different land use in both mined and

unmined fields. This showed that the outliers did not dominate the measures of central tendency. The soils were

uniform for all experimental sites in the study area and according to USDA classification were silt-loam with silt

content ranging from 69 per cent to 73 per cent. The CV for sand, silt and clay contents was low (<12 per cent in

unmined sites and <13 per cent in reclaimed sites under forage, corn or soybean) for both depths. The CV for �b,

pH and SOC mostly ranged from moderate to low across all land uses in both reclaimed and unmined fields for

Table I. Descriptive statistics for soil bulk density (�b; mg m�3), soil organic carbon (SOC; mg ha�1) and total nitrogen stocks(TN; mg ha�1), and soil pH in unmined fields for 0–10 cm depth

Property Mean Median SE CV Skewness Minimum Maximum

Forage�b 1�27 1�25 0�02 0�03 0�84 1�23 1�33pH 6�20 6�22 0�06 0�02 �1�12 5�94 6�38SOC 22�74 20�10 1�91 0�21 1�36 19�66 30�79TN 2�57 2�33 0�20 0�19 1�27 2�20 3�40

Corn�b 1�22 1�24 0�04 0�07 �0�48 1�11 1�32pH 6�19 6�18 0�27 0�11 0�01 5�43 6�93SOC 21�48 21�38 0�29 0�03 0�35 20�56 22�55TN 3�36 3�12 0�53 0�39 0�25 2�06 4�90

Soybean�b 1�29 1�26 0�06 0�11 1�21 1�12 1�56pH 5�99 5�94 0�08 0�03 0�51 5�81 6�24SOC 25�60 24�48 1�78 0�17 2�01 21�97 34�15TN 2�78 2�72 0�17 0�15 1�45 2�39 3�56

SE, standard error; CV, coefficient of variation.

Table II. Descriptive statistics for soil bulk density (�b; mg m�3), soil organic carbon (SOC; mg ha�1) and total nitrogen (TN;mg ha�1) stocks, and soil pH in unmined fields for 10–20 cm depth


Forage�b 1�21 1�21 0�06 0�12 0�06 1�06 1�37pH 6�29 6�33 0�06 0�03 �0�22 6�10 6�50SOC 17�58 17�47 0�66 0�09 0�83 15�87 20�29TN 1�96 1�96 0�08 0�10 0�56 1�76 2�26

Corn�b 1�32 1�35 0�04 0�07 �0�53 1�20 1�42pH 6�22 6�07 0�27 0�11 0�52 5�54 7�13SOC 26�82 26�36 2�12 0�19 0�68 21�43 35�15TN 2�75 2�86 0�14 0�13 �0�54 2�30 3�13

Soybean�b 1�30 1�32 0�03 0�06 �0�48 1�21 1�38pH 6�22 6�28 0�15 0�06 �0�56 5�65 6�69SOC 26�30 25�21 3�08 0�29 1�15 17�52 39�70TN 3�79 3�29 0�65 0�42 1�68 2�55 6�77



both depths. The CV for SOC was high only in reclaimed fields under soybean for 10–20 cm depth and that for TN

was low to moderate for unmined fields under forage for both depths and reclaimed fields for the 0–10 cm layer.

For corn and soybean fields, the CV for TN varied from moderate to high. The moderate variability for SOC and

TN were also reported in other studies (Agbu and Olsen, 1990; Cambardella et al., 1994; Shukla et al., 2004b).

Land Use and Soil Bulk Density

The �b differed among unmined fields planted to forage, corn and soybean for both depths, but only for 10–20 cm

depth in the reclaimed fields (Figures 2 and 3). However, �b was higher in reclaimed fields under forage than

soybean (P< 0�05). The unmined forage field was not tilled whereas fields under corn and soybean were chisel

tilled annually; still the lack of any differences observed in �b was somewhat surprising. However, it seems that the

Table III. Descriptive statistics for soil bulk density (�b; mg m�3), soil organic carbon (SOC; mg ha�1) and total nitrogenstocks (TN; mg ha�1), and soil pH in reclaimed fields for 0–10 cm depth


Forage�b 1�19 1�18 0�02 0�03 1�00 1�15 1�26pH 6�57 6�62 0�13 0�05 �0�65 6�10 6�86SOC 39�59 39�78 0�61 0�04 �0�54 37�34 41�15TN 3�84 3�88 0�06 0�04 �0�52 3�62 3�99

Corn�b 1�34 1�30 0�11 0�19 0�22 1�05 1�65pH 6�63 6�94 0�37 0�14 �0�83 5�27 7�49SOC 28�27 28�98 2�60 0�23 �0�71 18�02 35�24TN 4�86 5�28 0�76 0�38 �0�48 2�40 6�84

Soybean�b 1�39 1�38 0�03 0�05 0�35 1�31 1�49pH 5�35 5�19 0�27 0�12 0�96 4�74 6�43SOC 22�07 23�03 1�52 0�17 �0�86 15�98 26�34TN 2�16 2�21 0�14 0�15 �0�88 1�61 2�55

Table IV. Descriptive statistics for soil bulk density (�b; mg m�3), soil organic carbon (SOC; mg ha�1) and soil nitrogen (SN;mg ha�1) stocks, and soil pH in reclaimed fields for 10–20 cm depth


Forage�b 1�42 1�45 0�10 0�04 �0�25 1�08 1�73pH 6�52 6�74 0�35 0�11 �0�64 5�27 7�40SOC 32�15 30�80 3�52 0�24 0�45 23�48 44�67TN 4�37 4�30 0�68 0�64 0�16 2�53 6�52

Corn�b 1�42 1�45 0�10 0�17 �0�25 1�08 1�73pH 6�52 6�74 0�35 0�13 �0�64 5�27 7�40SOC 32�15 30�80 3�52 0�27 0�45 23�48 44�67TN 4�37 4�30 0�68 0�38 0�16 2�53 6�52

Soybean�b 1�51 1�50 0�03 0�05 1�01 1�42 1�64pH 5�26 4�97 0�26 0�12 0�97 4�74 6�26SOC 22�92 20�13 3�86 0�41 1�42 14�18 39�97TN 2�25 2�04 0�32 0�35 1�18 1�53 3�62



no-till increased the �b in forage fields and the compaction caused by tillage-related vehicular traffic increased �b

in corn and soybean fields. The mean �b was consistently lower in unmined than reclaimed fields irrespective of the

current land use. Since �b was measured after the harvest of crops, a higher �b for reclaimed fields was consistent

with higher tillage intensity in reclaimed than unmined fields.

Land Use and SOC Concentration

The soil pH did not differ among unmined fields and varied from 6�0 for soybean to 6�2 for forage for the 0–10 cm

depth and 6�2 for soybean to 6�3 for forage for the 10–20 cm depth. However, pH was higher for forage (6�6 for 0–

10 cm and 6�5 for 10–20 cm depths) and cornfields (6�6 and 6�5) than soybean (5�4 and 5�3) in reclaimed sites

(P< 0�05). The SOC concentration in unmined fields did not differ significantly among land uses (p< 0�05) for the

Figure 2. Effect of land use on (A) soil bulk density (�b), (B) soil organic carbon (SOC) and (C) total nitrogen (TN) stocks in unmined soilunder forage (UMF), corn (UMC) and soybean (UMS), the bars are standard errors of means.



0–10 cm depth (Table V). It varied in the order soybean field (22�16 g kg�1)> forage (13�54 g kg�1) in the 10–

20 cm depth (P< 0�05). The TN concentration also did not vary in unmined fields for the 0–10 cm depth but was in

the order soybean field (3�13 g kg�1)> corn (2�08 g kg�1)¼ forage (1�51 g kg�1) for the 10–20 cm depth

(P< 0�05). The SOC and TN concentrations were higher for the 0–10 cm depth than the 10–20 cm depth in

forage field, which was not tilled. However, for corn and soybean fields, the SOC and TN concentrations were

similar for both depths indicating the mixing by tillage.

The SOC concentration in reclaimed fields varied in the order forage field (33�30 g kg�1)> corn

(21�22 g kg�1)> soybean (15�88 g kg�1) for the 0–10 cm depth and cornfield (22�40 g kg�1)> soybean

(15�34 g kg�1) for the 10–20 cm depth (P< 0�05) (Table V). The TN concentrations in reclaimed fields were

similar for forage (3�23 g kg�1) and cornfields (3�66 g kg�1) and were higher than that for soybean fields

Figure 3. Effect of land use on (A) soil bulk density (�b), (B) soil organic carbon (SOC) and (C) total nitrogen (TN) stocks in reclaimed soilunder forage (UMF), corn (UMC) and soybean (UMS), the bars are standard errors of means.



(1�55 g kg�1) for 0–10 cm depth. For 10–20 cm depth, TN concentrations were in the order of cornfield

(3�31 g kg�1)> soybean (1�51 g kg�1) (P< 0�05). The SOC (7�84 g kg�1) and TN (0�95 g kg�1) concentrations

from a nearby mined but unreclaimed spoil were lower than mined and reclaimed sites.

The SOC concentrations were consistently higher for reclaimed forage and cornfields than unmined fields. The

differences in the SOC concentrations were high in reclaimed (33�30 g kg�1 for 0–10 cm and 20�33 g kg�1 for 10–

20 cm depths) and unmined (17�47 g kg�1 for 0–10 and 13�54 g kg�1 for 10–20 cm depths) forage fields. The TN

concentrations were also higher for reclaimed forage and cornfields than unmined fields (Table V). These results

indicate the contribution of manure, which was applied on reclaimed sites only, towards increasing SOC

concentration. The increase in SOC concentrations due to manure application was also reported in another study

in western Ohio by Shukla and Lal (2004). The CV for SOC concentrations in reclaimed forage field was low (0�06

for 0–10 cm and 0�11 for 10–20 cm depths). Carbon concentration of coal can vary from 40 g kg�1 to 80 g kg�1

depending upon the variety of coal. Although contamination of soil sample with coal cannot be totally ruled out,

the SOC concentrations from reclaimed sites were always lower than pure coal carbon concentration and no

outliers were detected for any of the soil samples. Therefore, influences due to coal contamination were considered

insignificant and ignored.

Land Use and Soil Organic Carbon Stock

The SOC stock in unmined soils did not differ among forage (22�7 mg ha�1), corn (21�5 mg ha�1) or soybean

(25�6 mg ha�1) fields for the 0–10 cm depth but varied in the order cornfield (26�8 mg ha�1)¼ soybean

(26�30 mg ha�1)> forage (17�58 mg ha�1) for the 10–20 cm depth (P< 0�05) (Figure 2). The TN stocks in

unmined soils also did not differ among land uses for the 0–10 cm depth but were higher for soybean fields

(3�8 mg ha�1) than forage (2�0 mg ha�1) for 10–20 cm depth (P< 0�05).

The SOC stock in reclaimed fields were forage (39�6 mg ha�1)> corn (28�3 mg ha�1)¼ soybean (22�1 mg ha�1)

for the 0–10 cm depth but did not differ among land uses for the 10–20 cm depth (Figure 3). The SOC stocks for

unreclaimed spoil (11�6 mg ha�1) were the least for the 0–10 cm depth. The TN stocks in reclaimed fields were in

the order cornfield (4�9 mg ha�1)¼ forage (3�8 mg ha�1)> soybean (2�2 mg ha�1) for the 0–10 cm depth and

varied as cornfield (4�4 mg ha�1)> forage (2�9 mg ha�1)¼ soybean (2�3 mg ha�1) for the 10–20 cm depth

(Figure 3). The TN stocks for a nearby unreclaimed spoil were the least (1�4 mg ha�1).

In accord with the SOC concentration, the SOC stocks for reclaimed forage and cornfields were higher than

those for the unmined fields for both depths. The higher SOC stock for reclaimed forage fields than unmined forage

fields was consistent with higher SOC concentration and �b for the former. The light fraction SOC is free and a part

of it is physically stabilized in macroaggregates (Cambardella and Elliot, 1992). This fraction is highly

decomposable, and is a function of cropping and tillage and can show seasonal variation (Boone, 1994). A

Table V. Soil organic carbon (SOC), soil nitrogen (TN) concentrations (g kg�1) inunmined soil (UMS) and reclaimed minesoils (RMS) under forage, corn andsoybean system

SOC (0–10) SOC (10–20) TN (0–10) TN (10–20)

UMSForage 17�47 13�54b 1�98 1�51bCorn 17�70 20�22ab 2�76 2�08bSoybean 20�24 22�16a 2�20 3�13aDCR (P< 0�05) NS 6�86 NS 0�83

RMSForage 33�30a 20�33ab 3�23a 2�07abCorn 21�22b 22�40a 3�66a 3�31aSoybean 15�88c 15�34b 1�55b 1�51bDCR (P< 0�05) 3�34 6�47 0�97 1�38

DCR is Duncan’s multiple comparison.



high SOC stock for reclaimed forage field could also be due to the short-term shift in SOC storage due to tillage

and the dynamic nature of this pool with a bulk turnover time of months to a year. The SOC stock for reclaimed

forage was more than three-times higher than unreclaimed spoil. The SOC stock in reclaimed fields planted to

forage was nearly double than that for soybean fields. Since spoil was not reclaimed and no topsoil was applied,

SOC stock of spoil cannot be taken as a baseline value. In the absence of a true initial baseline value immediately

after the reclamation and to get an idea about the rate of SOC sequestration in reclaimed soils, mean SOC stock of

reclaimed fields under soybean was taken as a baseline value. Therefore, with respect to soybean, in the ten years

from 1992 to 2002, the forage fields sequestered SOC at the rate of 1�46 mg ha�1 y�1 for the 0–10 cm and

0�47 mg ha�1 y�1 for the 10–20 cm depths. Similarly, cornfields sequestered SOC at the rate 0�52 mg ha�1 y�1 for

the 0–10 cm and 0�77 mg ha�1 y�1 for the 10–20 cm depths.

Coal mining is an important economic activity in Ohio and about 85 per cent of electricity is generated using

coal. However, surface mining or topsoil removal severely depletes the structure and organic carbon content of soil

and leads to severe land degradation and environment pollution. This study clearly demonstrates the usefulness of

minesoil reclamation. Ten years after the surface mining, the SOC stocks were higher in the reclaimed fields than

the adjacent unmined sites. The reclaimed area was brought back to the pre-mining cropping system six years after

the reclamation, which clearly shows that the reclamation, if done properly, restores and improves soil and

environmental quality.

CONCLUSIONS

The variability of physical properties of silt loam soil (i.e., soil bulk density, pH and soil organic carbon stock) was

moderate to low (CV< 0�35) across all land uses in both reclaimed and unmined fields for both depths. The soil

nitrogen stock varied from low to moderate for unmined fields and moderate to high in some reclaimed fields. The

mean soil bulk density was consistently lower in unmined fields than reclaimed fields irrespective of the land use.

The SOC and TN concentrations were consistently higher for reclaimed forage and cornfields than unmined fields.

These results showed the important contribution of manure, which was applied only on reclaimed sites, towards

increasing SOC concentration. The SOC stocks in unmined soils did not differ among forage, corn or soybean

fields but did vary in reclaimed soils for the 0–10 cm depth. The SOC stocks for reclaimed forage and cornfields

are higher than those for the unmined fields for both depths. A high SOC stock for reclaimed forage fields could

also be due to the short-term shift in SOC storage due to tillage and the dynamic nature of light fraction organic

carbon pool with a bulk turnover time of months to a year.

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