CP Phase III Final Report 1991_Part 2.pdf - Lee Daniels - Soil and ...

FINAL REPORTTHE EFFECTS OF CONTROLLED OVERBURDEN PLACEMENTON TOPSOIL SUBSTITUTE QUALITY AND BOND RELEASE:PHASE IIIOSM COOPERATIVE AGREEMENT HQ51-GR87-10022Kathryn Haering, W.Lee Daniels, John Torbert, and James BurgerDepartment of Crop and Soil Environmental SciencesDepartment of ForestryVirginia Polytechnic Institute and State University

II. MINE SOIL FERTILITY AND PLANT NUTRITIONStanding Biomass ProductionAll rock mix plots received an initial N-P-K fertilization in spring1982 and annual additions of 56 Kgfha N in fall 1982, 1983, 1984 , and 1985to simulate the N that would be added by a vigorous legume component.Standing biomass production in the rock mix experiment shows the effect ofthese annual N additions . Yields on the rock mix plots were higher in 1982and 1983 (Table 15).Although yields in 1984·, 1986, and 1987 were lower,the rock mix plots outperformed the control, topsoil , sawdust, and 22Mgfha sludge plots of the surface amendment experiment during these years,apparently because the N reservoir established by the annual N additionswas still active. In 1989, however, rock mix experiment yields were muchlower than in 1987, and were similar to the yields on the control plots ofthe surface amendment experiment.Mixtures containing a high proportion of sandstone initiallyoutyielded pure siltstone spoils, but by 1984, yields on all rock mixplots were not significantly different. In some cases, mixtures thatinitially produced the highest yields had the lowest yields in followingyears .High standing biomass production stimulated by N additions mayhave tied up avail able N in litter so that it was not available for plantnutrition in subsequent years.In 1989, all the rock mixtures had similaryields .The control, topsoil, and sawdust plots of the surface amendmentexperiment received an initial N-P-K fertilization, with sawdust plotsreceiving an additional amendment of slow-release N to compensate for38

Table 15. Annual standing biomass production of tall fescue growingon mine soils of the controlled overburden placement experiment.-------------------------year----------------------Treatment 1982 1983 1984 1986 1987 1989----------------------Mg/ha-----------------------Rock Mix ExperimentSandstone (SS) 6.3a 6.5bc 5.7a 3.4ab2:1 SS:SiS 6.0a 9.3a 4.la 3. 9ab1:1 SS:SiS 6.0a 7.6b 5.2a 2.9b1:2 SS:SiS 4.4b 6 . 4bc 6.3a 4.4aSiltstone (SiS) 3.7b 5 .2c 4.4a 4.2ab2.8a 1. 6ab2.6a 1. Sb3.0a 2.4a2 . 6a 1.8ab2 . 5a 1. 6abSurface Amendment ExperimentControl(2:1 SS:SiS)Topsoil(30 ern)Sawdust(112 Mg/ha)Sludge(22 Mg/ha)Sludge(56 Mg/ha)Sludge(112 Mg/ha)Sludge(224 Mgjha)5.8cd5.8cd3.7d3.9d7.7bc9. 3ab10 .7a5.9c 0.9e 1. 6c5.2c 1 . 7de 2 . 0c5.6c 2.8cd 2.4bc5.2c 2.7cd 2.6bclO.lb 4.4bc 5 .2ab13. 6ab 4.8b 7.2a16.5a 7.5a S . Oabl.lc 2. 2a1. 7abc 3.6a1. 4bc 2. 8a1. 7abc 2 .4a2.5ab 4 .4a2.8a 4.6a2 . 4ab 4.4aColumn means followed by different letters by years aresignificantly different, P=O.OS (Fisher' s LSD).39

microbial N immobilization due to high carbon/nitrogen ratio, The controland topsoil plots produced their highest yields in 1982 and 1983, whilethe yields for the organically amended plots were highest in 1983 asnutrients became increasingly available through organic matterdecomposition and nitrogen release. Yields declined in 1984, presumablybecause of lack of readily available nutrients, and generally stayed lowuntil 1989, when they rose again.This may indicate that levels ofnutrients sufficient to maintain biomass production over time are beingprovided by the fescue uptake/litter decomposition cycle.Yields were extremely variable by plot in 1989, because of thetendency of unmowed and unrenovated fescue stands to grow in clumps. Thusthe 1989 standing biomass production data for the surface amendmentexperiment shows no significant statistical difference among treatments.However, plots treated with 56 Mgjha or more of sewage sludge haveconsistently maintained the highest levels of standing biomass productionover the eight years of the experiment .Soil Organic MatterOrganic matter content of the surface (0- 5 em) layer of the mine soilsin both experiments was measured by the Walkley-Black method. This methodmeasures organic matter by chemical oxidation._ If ferrou~soxides are present, the _ w_ill_ r_e_suJ...t._in__a_p..osit.Lv.e_e.n:.oJ:....£or_ Qr-&!!lic-~--- -matter content. Soils of the rock mix exp~!~ment show~d inc~~a~ing organicmatter content with increasing proportion of siltstone, apparently becausethe siltstone spoils contained more reduced Fe and Mn comp?unds than theoxidized sandstone.Since the surface amendment treatments were all40

applied to spoils with the same mixture of sandstone and siltstone,relative differences in organic matter content over treatment and time canbe observed (Table 16). Because of the error inherent in the method, theseshould not be considered to be absolute organic matter values . The organicmatter value for the topsoil treatment is likely to be nearest the correctvalue since the preweathered soil horizons used as topsoil probably didnot contain significant amounts of reduced Fe and Mn compounds.Organic matter content of all of the surface amendment treatmentsexcept the sawdust plots increased over time. Organic matter in thesawdust plots remained fairly constant over time, apparently becausenear-equilibrium levels of organic matter were added to begin with. Thetwo highest sludge rate treatments also appear to be reaching equilibriumorganic matter levels.In 1982, organic matter content increased assludge rate increased, but by 1987, the organic matter content of thethree highest sludge rates was similar.Equilibrium organic mattercontent for the upper 5 em of these organically amended mine soils appearsto be near 6 to 7 percent (as measured by the Walkley-Black method.)Total Soil NitrogenIn the rock mix experiment, total soil N content of the upper 5 em wasmeasured in 1983, 1984, and 1987.The pure siltstone treatment had thehighest total N levels while t he pure sandstone treatment had the lowest(Table 17) .Siltstone overburden contains a significant amount ofgeologically fixed N which contributes to the total N content of soilsforming on this parent material.Total N levels have risen each year inevery treatment; levels in 1987 were 3 to 4 times greater than in 1983 .41

Table 16. Organic matter content of the surface (0-5 em) layer ofmine soils of the surface amendment experiment, sampled in 1982,1983, 1984 and 1987.- ---------- - -year------------ - - -- --Treatment 1982 1983 1984 1987-- - - -- -- % organic matter ---- -----Control (2:1 SS:SiS) l . OOa 2.03a 2.24a 3.19aTopsoil (30 em) 0.95a 1 . 16b 1.36b 2.33aSawdust (112 Mgjha) 7.43d 9.33f 8.47f 7.27bcSludge (22 Mg/ha) 2 . 08ab 3 . 24c .3 . 66c 5 . 53dSl udge (56 Mg/ha) 3 . 20b S.OSd 4.8ld 7.92bSludge (112 Mg/ha) 5 .44c 6 . 42e 6 . 99e 6.64cdSludge (224 Mgjha) 6 . 03cd 6 . 72e 6.42e 7.14bcColumn means followed by different letters by experiment aresignificantly different (P- 0.05, Fisher's LSD).42

Table 17. Total nitrogen content of the surface (0-5 em) layer ofmine soils of the rock mix and surface amendment experiments,sampled in 1982, 1983, 1984 and 1987.-- -----------year--- ---------------Treatment 1982 1983 1984 1987------------ g/kg N ---------------Rock Mix ExperimentSandstone (SS)2:1 SS:SiS1:1 SS:SiS1:2 SS:SiSSiltstone (SiS)0.36a0.48ab0.53b0.53b0.8lc0. 60a 1.32a.0. 90b 1. 79bc0.93b 1. 64abl.lSbc 1. 57ab1.22c 2.09cSurface Amendment ExperimentControl (2:1 SS:SiS) 0.62a 0.8labTopsoil (30 em) 0. 36a 0.56aSawdust (112 Mgjha) 1. 85b 2.14cSludge (22 Mgjha) 1.19ab 1 .4SbcSludge (56 Mgjha) 1. 99b 3.20dSludge (112 Mgjha) 3.59c 3.88dSludge (224 Mgjha) 4.2lc- ---=--"'-4.65e0. 97ab 1.42a0.59a 1.12a1. 98c 2.40b1. 7lbc 2.70b2.5lc 3.50c4 . 57d 3.70c4.19d 4.56dColumn means followed by different letters by experiment aresignificantly different (P - 0.05, Fisher's LSD).7 ,-- I43

This is apparently a result of additions of N both from litter and rootdecomposition and from fertilization.Over the course of time, the highest total N levels in the surfaceamendment experiment were generally found in the 56 Mg(ha, 112 Mg(ha, and224 Mg(ha sludge treatments. The control and topsoil plots had thelowest N levels. Total N has increased over time in the control, topsoil,22 Mg(ha and 56 Mg(ha sludge plots, while the sawdust, 112 Mg(ha and 224Mg(ha sludge plots have had fairly stable N levels over the course of theexperiment.This indicates that near-equilibrium N and organic matterlevels were probably achieved by the addition of large amounts of bothsludge and sawdust, along with the slow-release N that was added to thesawdust plots. The organic matter content in these plots also remainedfairly stable with time. Increasing N content in the remaining treatmentsindicate that N has been added through litter and root decomposition, andthat these treatments are apparently still reaching equilibrium N levels .Fescue Nitrogen Content and Nitrogen UptakeBoth fescue N content (Table 18) and total fescue N uptake, which iscalculated from fescue N content and yield of standing biomass (Table 19)are an indication of the amount of plant-available N in these mine soils .Fescue N content generally increased over time in the rock mix experiment,although it declined slightly in 1984, apparently because readilyavailable N from the initial fertilizer application had been tied up inthe large amounts of biomass produced in 1982 and 1983.Fescue N levels were not significantly different between the rock mix44

Table 18. Nitrogen content of tall fescue tissue grown on minesoils of the rock mix and surface amendment experiments, sampled in1982, 1983 , 1984, 1987, and 1989.Treatment------ --------------year--------- -----------1982 1983 1984 1987 1989------------------ g/ kg N ------------------Rock Mix ExperimentSandstone (SS)1:1 SS:SiSSiltstone (SiS)9.9a10.2a9.0a9.3a9.8a10.4a7 .0a8.0b8.0b11. 7a11 . 7a12.la12.0a15. 2ab16 .3bSurface Amendment ExperimentControl (2:1 SS:SiS)Topsoil (30 em)Sawdust (112 Mgjha)Sludge (56 Mgjha)Sludge (112 Mgjha)8.5a8. 7ab9.4ablS.Sc18 . 2c13 . Oab10.6a11. 8ab2l.Oc20 . 9clO.lab9.la9.7a11 . 7b16.0c16 .la15.2a16.9a15.3a15 . la12.2a13. 7ab13.7ab13. 4ab14.5bColumn means followed by different letters by experiment aresignificantly different (P = 0.05, Fisher's LSD).45

Table 19. Annual nitrogen uptake by fescue growing on mine soils ofthe controlled overburden placement experiment.Treatment1982 1983year1984 1987 1989------------------ kgfha N ------- - ----------Rock Mix ExperimentSandstone (SS)1:1 SS:SiSSiltstone (SiS)62.la60.2a33 .3b60.4a77 .Sa53.8a39.2a40.0a34 . 6a32 .7a36.4a28. 9a19.8a34.9b25 . 9abSurface Amendment ExperimentControl (2:1 SS:SiS)Topsoil (30 em)Sawdust (112 Mg/ha)Sludge (56 Mgfha)Sludge (112 Mgfha)49 . 6a 76.6a 9 .3a50.3a 53.la lS.Oa34.2a 67.4a 26.3a118 .1b 214.6b 52.6b165.6b 284.2b 74.2b18 .1a26. 2ab23. 9ab37.4bc42.2c26.8a46. 6ab36 .Oab70.9b58 . labCo lumn means followed by different letters by experiment aresignificantly different (P- 0.05, Fisher's LSD) .46

treatments in 1982, 1983, and 1987 .By 1989 , N content of fescue grown onthe siltstone treatment was significantly higher.Some of this increasein fescue N may have resulted from weathering and subsequent availabilityand uptake of geologically fixed N in the siltstone parent mat erial,although the plant-availability of this fixed N is generally thought to bequite low.Because of higher yields, N uptake was initially higher in thepure sandstone and mixed treatments . By 1989, higher fescue N contentsresulted in N uptake levels being highest on the pure siltstone treatment .In the surface amendment experiment, fescue N content increased from1982 to 1987, with a decline in 1984 apparently caused by N immobilizationin biomass .Fescue N content dropped slightly in 1989, and was comparableto 1989 levels for the rock mix experiment. For the first three years,s ludge amended plots had higher fescue N content than the control, topsoiland sawdust plots. Although fescue N content in 1987 was notsignificantly different between the surface amendment treatments, in 1989the control treatment h a d t h e lowest fescue N content and t he highestfescue N levels were found in the 112 Mg(ha sludge treatment.Because of high yields and high N levels, the sludge amended plots hadt he highest N uptake levels during the first three years of the study.Inall years, however, at least one of the sludge t reatments hadsignif icantly higher N uptake levels t han those of the control plots.Extractable PhosphorusExtractable P l evels in t h e s urface (0 - 5 em) l ayer of t he rock mixexperiment were highest during the first year of the study and lowest in47

Table 20. Bicarbonate-extractable phosphorus content of the surface(0-5 ern) layer of mine soils of the rock mix and surface amendmentexperiments, sampled in 1982, 1983, 1984 and 1987 .---------------year----------- - - - --- - -Treatment 1982 1983 1984 1987----- - --------- rng/kg P - ------------ -Rock Mix ExperimentSandstone (SS)2:1 SS;SiS1:1 SS :SiS1:2 SS;SiSSiltstone (SiS)SurfaceControl (2:1 SS:SiS)Topsoil (30 ern)Sawdust (112 Mg(ha)Sludge (22 Mg(ha)Sludge (56 Mg(ha)Sludge (112 Mg(ha)Sludge (224 Mg(ha)78.1a75 . 4a64.0a74.3a74 . 0aAmendment54 . 1ab35 . 5bc24. 3c21.9c43.9bc80. 9a126 .1d46.9a 52 . 0a 31.0a51 . 9a 37 . Oab 25.9a42.la 39. 7ab 27 . 6ab45.9a 37.1ab 26. 9ab39.3a 29 . Sb 18 . 9bExperiment50 . 4a 27. 2ab 27.1a41. Sa 29 . 1a 28.0a42 .1a 27 . 3c 19.0a36 . 3ac 27.6bc 42.0a82.4b 50 . 3c 70 . 0b120.lc 79.9d 81.2b145.0c 79 . 0d 106 . 9cColumn means followed by different letters by experiment aresignificantly different (P = 0.05, Fisher's LSD).48

1~87, the last year that they were measured (Table 20) . This decrease inextractable P was probably caused by P fixation by Fe , Ca, and Al mineralsreleased by spoil weathering.P is also taken up by fescue andsequestered in undecomposed plant material.In 1982 and 1983 , there wereno significant differences in extractable P among the t reatments of therock mix experiment, but in 1984 and 1987, P was significantly higher inthe pure sandstone treatment than in the pure siltstone treatment.Thesiltstone overburden used in this study contains a higher percentage ofCa-carbonates than the sandstone overburden, and has a greater capacity tofix P as Ca-P compounds. In the P adsorption isotherms for the 1982, 1983and 1984 samples, P adsorption in the surface layer of the siltstone plotsincreased over time because of the formation of Fe-oxide surface coatings.This effect was not observed in the sandstone plots, where P is likely tobe found in the form of non-occluded Fe-phosphates which are partiallyremoved with the extracting solution used in this study.In the surface amendment experiment, P levels in the control plotsshowed the same trends over time as did those in the rock mix experiment.Extractable P was highest during the first year of the experiment andlowest in 1987.In the sawdust, and sludge treatments, P was generallyhighest in 1983, the second year of the experiment. This may indicate thatless P fixation took place immediately in these treatments and that asignificant amount of P may have been released by the decomposition oforganic matter. The lowest extractable P levels in the sawdust and topsoilplots were found in 1987.In contrast, extractable P levels in the sludgeamended plots rose or remained fairly stable between 1983 and 1987. Thehigh organic matter content of these plots may have led to the formation49

o£ organic acids which complexed P-fixing elements in the spoil andreduced inorganic P fixation, althougb the same effect was not observed inthe sawdust plots.The three highest sludge rate treatments had the highest extractable Plevels over the course of the experiment, with extractable P generallyincreasing with sludge rate. A large amount of organic P was addedinitially as a component of the sludge and has apparently remained inavailable form over time, possibly as Ca-P and Fe-P complexes with organicmatter.Fescue Phosphorus Content and Phosphorus UptakeAlthough extractable soil P decreased over time, fescue P content inthe rock mix experiment actually increased with time (Table 21) .Thiscould indicate that the bicarbonate extraction used to measure P in thesemine soils was not a good indicator of the amount of plant-available soilP, or could have been caused by lower biomass production, making more Pavailable for uptake by each plant.Fescue P content in the rock mixexperiment dropped slightly in. 1983 and 1984, but increased in 1987.Highest P levels were measured in 1989 . Significantly higher t reatment Plevels were measured in the 1:1 sandstone mix in 1984 and 1987.Higheryields in the mixed spoil treatment may have created a larger pool oforganic P which was made available by litter decomposition . By 1989, therewas no significant difference in tissue P content between rock mixtreatments.During the first two years of the study, P uptake (Table 22) was50

Table 21. Phosphorus content of tall fescue tissue grown on minesoils of the rock mix and surface amendment experiments, sampled in1982, 1983 , 1984, 1987, and 1989.Treatment---------------- - ---year------------------ - -1982 1983 1984 1987 1989------------------ g/kg p ------------------Rock Mix ExperimentSandstone (SS)1:1 SS:SiSSiltstone (SiS)1. 98a1.83a1.56a1.66a1.84a1. 69a1. 32a1.64b1. 32a2.18ab2.44a1. 86b2.39a2.78a2.48aSurface Amendment ExperimentControl (2:1 SS:SiS)Topsoil (30 em)Sawdust (112 Mgfha)Sludge (56 Mgfha)Sludge (112 Mgfha)1.96a 3 .12ab 2.79a1.94a 2.40c 2.60a1.46a 2.59bc 2 . 69a4.00c 4.63d 4.13b3.48b 3.82a 3.75b3.46a2 . 94a3.16a3.76a3.74a2.89ab2 . 83ab2.87ab2.38b3.38aColumn means followed by different letters by experiment aresignificantly different (P - 0.05, Fisher's LSD).51

. Table 22. Annual phosphorus uptake by fescue growing on mine soilsof the controlled overburden placement experiment.Treatment1982 1983year1984 1987 1989----------- - -- - --- kg(ha P ------- - ---- - ---- -Rock Mix ExperimentSandstone (SS)1:1 SS:SiSSiltstone (SiS)12.5a10.8a5 . 8b10.8a14.1b8.9a7.5a8.3a5.6a6 . 3a7.2a4.5a4.0a4 . 8a4.0aSurface Amendment ExperimentControl (2:1 SS:SiS)Topsoil (30 ern)Sawdust (112 Mg/ha)Sludge (56 Mg(ha)Sludge (112 Mgjha)11. 4a 17.8a 2.5a11.2a 12 . 0a 4.0a5.8a 14. 9a 7.2a31.1b 46.9b 18 . 5b31. Sb 53 . 6b 18.6b3.9a4.0a4.4a9.0b10.4b6.4a8.9a7.2a13.3a13.laColumn means followed by different letters by experiment aresignificantly different (P- 0.05, Fisher's LSD).52

highest in the mixed sandstone/siltstone treatment because of higheryields. Values for P uptake in 1984 , 1987, and 1989 were notsignificantly different among rock mix treatments.Fescue P content in the surface amendment experiment generallyincreased each year until 1987 in the control, topsoil, and sawdusttreatments, probably because of bio-additions of P in decomposing litterand the concentration effect caused by lower yields.In the sludgetreatments, which had the highest tissue P levels over the first threeyears of the experiment , fescue P fell slightly over time. By 1989, tissueP levels in both the sludge and other surface amendment treatments weresimilar. The highest P uptake values in every year were found in thesludge treatments because of higher biomass production.Fescue Potassium ContentFescue tissue K levels in the rock mix experiment showed nosignificant treatment effects until 1989, when the 1:1 SS:SiS treatmenthad significantly higher fescue K levels than the sandstone treatment(Table 23) .Tissue K content in this experiment was slightly higherduring the first and last years of the study, but showed no clear trendsover time.In the surface amendment experiment, tissue K was generallyhighest in the sludge plots, presumably because K was added as a componentof the sewage sludge (Table 24).Tissue Kin the sludge-amendedtreatments were initially quite high, but decreased over time asequilibrium soil K levels were established.By 1989, all surfaceamendment treatments except the 112 Mg/ha sludge treatment had similarfescue tissue K content .The mine soils of both experiments appear to be53

Table 23. Levels of K, Ca, and Mg in tall fescue tissue grown onmine soils of the rock mix experiment in 1982 , 1983, 1984, 1987 and1989.Year Treatment K Ca Mg---------- gjkg ----------1982 Sandstone (SS) 17 . 5a 2.9la 2.47a1:1 SS:SiS 18 .la 3.33ab 2.74aSiltstone (SiS) 16.5a 3. 71b 2.70a1983 Sandstone (SS) 11.3a 3.07a 2.12a1:1 SS:SiS 12.8a 3.89b 2.54bSiltstone (SiS) 12 .8a 4.39c 2.9lb1984 Sandstone (SS) 11.9a 2 .8la 2.27a1:1 SS:SiS 13 . 0a 3. 35ab 2.63bSiltstone (SiS) 14.0a 3.60b 2.92b1987 Sandstone (SS) 12.6a 4.37a 2.54a1:1 SS:SiS 13. 7a 3.13a 2 . 50aSiltstone (SiS) 11 . 8a 3.49a 2.37a1989 Sandstone (SS) 12.4a 2 .69a 2.48a1:1 SS:SiS 16.3b 3.45b 2.87abSiltstone (SiS) 15.2ab 3.36b 2.93bColumn means followed by different letters by experimentare significantly different (P = 0 . 05, Fisher's LSD) .54

. Table 24. Levels of K, Ca, and Mg in tall fescue tissue grown onmine soils of the surface amendment experiment in 1982, 1983, 1984,1987 and 1989.Year Treatment K Ca Mg----------- g/kg ----------1982 Control (2:1 SS:SiS) 18.2a 3.42a 2 . 63aTopsoil (30 em) 17.3a 3.22a 2.74aSawdust (112 Mg(ha) 19.la 3.38a 2.89aSludge (56 Mg(ha) 24.6a 5.16b 3.43bSludge (112 Mg(ha) 23.3b 6 . 26c 3.43b1983 Control (2:1 SS:SiS) 15.la 4.2la 2.9labTopsoil (30 em) 12.5a 4.44a 2.65aSawdust (112 Mg(ha) 15 .4a 4.34a 2 . 85abSludge (56 Mg(ha) 2l.lb 4. 7la 3.09aSludge (112 Mg(ha) 23.0b 4.79a 3.14a1984 Control (2:1 SS:SiS) 9.la 3.64a 2 . 56abTopsoil (30 em) 8.5a 3.65a 2.39bSawdust (112 Mg(ha) 11.5b 3.12a 2 . 92cdSludge (56 Mg(ha) 17 . lc 4. 39b 3.44eSludge (112 Mg(ha) 20.9d 4.40b 3.15de1987 Control (2:1 SS:SiS) 16 . 3a 3.68a 2.96aTopsoil (30 em) 15.6a 2.85a 2.85aSawdust (112 Mg(ha) 17.9a 3.59a 2.89aSludge (56 Mg(ha) 17.6a 3.68a 2.44aSludge (112 Mg(ha) 17.8a 3.49a 2.5la1989 Control (2:1 SS:SiS) 13.2a 3.32a 2.26aTopsoil (30 em) l2.7a 3.19a 2.21aSawdust (112 Mg(ha) 14. 6ab 3.53a 2 . 49aSludge (56 Mg(ha) 14. 9ab 4.1la 2.60aSludge (112 Mg(ha) 16.4b 3.3la 2.42aColumn means followed by different letters by experiment aresignificantly different (P = 0.05, Fisher's LSD).55

maintaining K levels adequate for fescue nutrition.Fescue Calcium and Magnesium ContentThe high Ca and Mg content of the mine soils in both experiments makeit unlikely that Ca or Mg would be limiting to fescue growth.In the rockmix experiment, during most years, fescue Ca and Mg were highest in thepure siltstone treatment and lowest in t he pure sandstone treatment,because the siltstone spoil has higher levels of exchangeable Ca and Mg(Table 23). Both Ca and Mg levels in fescue tissue remained fairlyconstant over time.The highest tissue Ca and Mg levels in the surface amendmentexperiment were found in the sludge amended treatments during the firstthree years of the study (Table 24).The sludge amended treatments hadhigher exchangeable soil Ca levels, but lower exchangeable soil Mg levelsthan the other treatments in this experiment.The high t issue Mg levelsindicate that the Mg in the sludge plots may have been present in a moreavailable form, perhaps as true exchangeable Mg rather than asMg-carbonates.In 1987 and 1989, tissue Ca and Mg levels in the surfaceamendment experiment were not significantly different among treatmentsand were similar to the tissue Ca and Mg levels found in the rock mixexperiment.Nutrient Suffiency/Toxicity Levels in Fescue TissueSamples of the upper half of fescue leaves were taken in July 1982 andSeptember 1988 and analyzed for nutrient sufficiency levels. Because ofthe sampling method, nutrient and metal levels are generally higher than56

those reported elsewhere in this report for analysis of the entireabove-ground portion of fescue plants.In both years, K, Ca, Mg, and Fe were well within sufficiency levelsin both the rock mix (Table 25) and surface amendment (Table 26)experiments. Levels of K and Ca were slightly lower in 1988 than in 1982,but were still more than adequate for fescue growth.Levels of Mg in both1982 and 1988 were similar in both experiments, although the higher sludgerate plots of the surface amendment experiment had lower Mg levels thanthe other treatments in 1988 .This may have resulted from the lowerexchangeable Mg content of the sludge amended plots.In 1982, both Nand P levels were close to deficiency levels in allbut the higher sludge rate plots. By 1988, fescue P content had risen towell within the sufficiency range in most treatments, with plots amendedwith high levels of sludge having the highest P levels . Levels of N haddropped, however , and by 1988, were below sufficiency levels in all plotsexcept those amended with 56 Mgfha or more of sludge.This suggests thatN, rather than P, becomes limiting over time in these mine soils. Since Nappears to be the major limiting nutrient , N deficiency could be correctedby the addition of a legume component to the fescue stand.The Mn concentrations measured in 1982 were within the reported rangeof toxicity in all treatments except those amended with high rates ofsludge. By 1988, Mn levels had dropped dramatically. The only treatmentthat still had high tissue Mn levels was the sandstone treatment of therock' mix experiment, but these levels were not close to the toxic range.57

Table 25. Sufficiency/toxicity levels of N, P, K, Ca, Mg, Fe, and Mnin upper 1/2 of fescue plant growing on mine soils of the rock mixexperiment (sampled in July 1982 and September 1988.)Treatment N p K Ca Mg Fe Mn---------------g/kg--------------------mg/kg-------------July 1982-------Sandstone 21. Sa 3.3a 36.2a 4.2a 3.3a 93 . 0a 499.0a2:1 SS:SiS 21.8a 3.3a 39.4a 4 . la 3.5ab 81. Sa 3ll.Oa1:1 SS:SiS 20.4a 3.0a 37.5a 4. Sab 3.7b 73.8a 385 . 5b1:2 SS:SiS 21. Sa 2.9a 35.7a S.lb 3.9b 78.3a 300.8bSiltstone 2l.Sa 2.8a 33.6a 4.9ab 3 .6ab 93 . 0a 310.8b-------September 1988------Sandstone 18.2a 3.9ab 31. Sa 3.2a 4.0a 9l . Oa 202.3a2:1 SS:SiS 18.2a 4.0ab 31. Sa 3.la 4.0a 80 . 3a 85.9b1:1 SS:SiS 18.4a 4.0ab 31. 9a 3.2a 4.0a 80.6a 83.0b1:2 SS:SiS 19 .4a 4.5a 33.la 3.3a 4.la 7S.3a 68.0bSiltstone 19.6a 3.Sb 32.7a 3 . 0a 3.9a 98.7a 56.3bMeans within columns in each year followed by the same letter arenot significantly different (P = 0.05).58

. Table 26. Sufficiency/toxicity levels of N, P, K, Ca, Mg, Fe, and Mnin upper 1/2 of fescue plant growing on mine soils of the surfaceamendment experiment in July 1982 and September 1988 .Treatment N p K Ca Mg Fe Mn--------- - -----g/kg-------------- -- -----mg/kg-------------July 1982----------Control 21.6a 3.6a 37.5ab 4 .Sa 3.8a 8l.Oa 405.3a(2:1 SS:SiS)Topsoil 21.3a 3.5a 39.5a 4.la 3.6a 97.0a 332. 8ab(30 em)Sawdust 28.2a 2.9a 32.6bc 4.3a 3.4a 108.5a 385.5a(112 Mgjha)Sludge 22 . la 3.4b 32. lbc 7 . 8a S.Oa 88.5a 269.8bc(22 Mgjha)Sludge 24. 7a 4.3b 33.5bc 7.1a S.la 92 . 8a 182.3cd(56 Mgjha)Sludge 25.5a 4.9b 33.8bc 6.7a 4. 7a 90.0a 136. 3d(112 Mgjha)Sludge 29.5a 4 . 5b 29.2c 8.2a S.Oa 97.5a 192.3cd(224 Mgjha)-------September 1988------Control 18.5a 4.4a 28.7a 3.3a 4.2a 76.8a 44. 7ab(2:1 SS:SiS)Topsoil 19.4ab 4.3a 31. 7ab 3 .4a 4.0ab 74.5a 51.6b(30 em)Sawdust 18.5a 4 . 2a 29.9ab 3.2a 4.0ab 76.7a 74.9c(112 Mgjha)Sludge 20.4bc S.lb 32.4b 3.7a 4 . 2a 73 . 8a 79.2c(22 Mgjha)Sludge 2l.lcd 5.7bc 29.4ab 3.6a 3.6b 89.4a 45. 2ab(56 Mgjha)Sludge 22.4d 6.1c 32.5b 3.4a 3.6b 73.7a 39.2ab(112 Mgjha)Sludge 22.2d 5.3b 30. 8ab 3.5a 3.lc 85.7a 30 . 0a(224 Mgjha)Means within columns in each year followed by the same letter arenot significantly different (P = 0.05) .59

Over time, Mn toxicity apparently ceases to be a limiting factor in fescuegrowth on these mine soils.Fescue Metal ContentLevels of Mn, Zn, Fe and Cu in selected treatments of the rock mix andsurface amendment experiments were measured in above-ground fescue tissuesamples taken in October 1987 (Table 27).The pure sandstone treatment ofthe rock mix experiment had significantly higher tissue Mn concentrationsthan the other rock mix treatments.Levels of Zn, Fe, and Cu were notsignificantly different among treatments in either experiment and werefound in similar concentrations in tissue collected from both the rock mixand surface amendment experiments. In the surface amendment experiment,sewage sludge rate appeared to have no effect on levels of Zn and Cu inthe 1987 fescue tissue samples.The use of sludge as a soil amendment often raises questions aboutheavy metal accumulation in vegetation grown on the treated soils .Thesewage sludge used in this study contained relatively low concentrationsof heavy metals.Plant tissue samples taken in 1982, however, show thatZn and Cu levels increased with increasing sludge rate (Table 28).TissueMn levels decreased with increasing sludge rate , apparently because theapplication of sludge had a diluting effect on native soil Mn levels. Theconcentration of Cd and Pb measured in the 1982 tissue samples was low,and there was no significant difference in tissue Cd and Pb levels betweenthe control and sludge treatments .By 1989, Zn and Cu levels showed no increase with sludge rate. Tissue60

. Table 27. Metal content of tall fescue tissue grown on mine soilsof the controlled overburden placement experiment, sampled October1987 .Treatment Mn Zn Fe Cu-----------mg/kg--------------Rock Mix ExperimentSandstone (SS)1:1 SS :SiSSiltstone (SiS)296.8a115. Ob156.7b27.la22 . 6a25 . 2a346.5a261 .8a332 .8a5.24a4.67a4.45aSurface Amendment ExperimentControl (2:1 SS:SiS) 101.5a 26.2aTopsoil (30 em) 86 . 8a 20.8aSawdust (112 Mgjha) 133 . 3a 27.2aSludge (56 Mgjha) lOO . Oa 20. SaSludge (112 Mgjha) 80.2a 26.4a478.0a417. 3a492.8a371. 4a385.4a5.38a5. 72a5 . 82a5.24a5.94aColumn means followed by different letters (by experiment)are significantly different , P=0.05 (Fisher's LSD).61

Table 28. Metal content of tall fescue tissue grown on control,and sewage sludge-amended plots of the surface amendment experimentin October 1982 and October 1989.Treatment Mn Zn Cu Cd Pb------------------ mgjkg ---------- - ---------------- 1982 ---------Control 572a 20a 3.8a 0.15a 4.3aSludge (22 Mg/ha) 233b 23a 4.4a 0.36a 5.8aSludge (56 Mgjha) 147c 37b 6.7b 0.23a 5.laSludge (112 Mg/ha) 140c 48c 8 . 7c 0.28a 1. SaSludge (224 Mg/ha) 132c 58d 8.4c 0.50a 4.4a--------- 1989 ---------Control 102a 26a 5.4a nd* nd*Sludge (22 Mgjha) 92a 24ab 6.0a nd ndSludge (56 Mg/ha) lOOa 20ab 5 .2a nd ndSludge (112 Mgjha) BOa 26a 5 . 9a nd ndSludge (224 Mgjha) 76a 18b 4 . 9a nd nd* nd - below detection limit for ICP (0.1 mg/kg Cd, 2.5 mgjkg Pb) intissue. Column means followed by different letters by experiment aresignificantly different (P - 0.05, Fisher's LSD).62

Mn was not significantly different between treatments.The levels of Cdand Pb in fescue tissue were low enough to be below the limit of detectionof the method used for analysis (0.1 mgfkg Cd; 2.5 mg/kg Pb) .Amendmentof these minesoils with sewage sludge containing relatively low heavymetal levels apparently does not cause elevated plant tissue metalconcentrations after several growing seasons .Litter Nutrient and Metal ContentThe Oe horizon, or litter layer, of both treatments was sampled inOctober 1987.This layer consisted mainly of dead fescue tissue anddecomposing organic material, but also contained some mineral matter .Certain plant nutrients are concentrated in litter because they arecontained in tissue compounds that are resistant to decomposition, whileother nutrients (such asK) are easily leached from the litter layer .Litter N content in both experiments was not significantly differentbetween treatments (Table 29).Both the rock mix and surface amendmentexperiments had similar levels of litter N, although the rock mixexperiment had lower tissue N levels in 1987.This may reflect acarry-over effect from the N fertilization of the rock mix experiment inprevious years.TheN content of the litter was generally higher t hanthat of the fescue tissue, possibly because N was concentrated during theprocess of organic matter decomposition. Levels of P in the l itter layerwere lower than those measured in the 1987 tissue samples.This may haveresulted from the lower tissue P levels measured in prev ious years of theexperiment.Litter P levels in the rock mix experiment were notsignificantly different, and were similar to litter P concentrations in63

Table 29. N, P, K, Ca, and Mg levels in tall fescue litter layersfrom the rock mix and surface amendment experiments, collectedOctober 1987.Treatment N p K Ca Mg- ------------- -g/kg------------------Rock Mix ExperimentSandstone (SS)1:1 SS:SiSSiltstone (SiS)18.58a17.29a16.46a1.25a1.2la1.18a3.06a3.63a3 .96a6.06a5.90a5.26a2.39a2. 79a3 .04aSurface Amendment ExperimentControl (2:1 SS:SiS) 18.70a 1. 38ab 4.00aTopsoil (30 em) 19.20a 1.44a 3.00bSawdust (112 Mg/ha) 13. 32a 1.13b 4.26aSludge (56 Mg/ha) 19 . 89a 1. 74d 3 . 62abSludge (112 Mgjha) 19.30a 1 .74d 3.59ab8.09a8.19a4.84b6.52ab6.68ab2.95a2.66a2. 77a2.88a2.82aColumn means followed by different letters (by experiment)significantly different , P=O.OS (Fisher's LSD).are64

the control, topsoil, and sawdust plots of the surface amendmentexperiment.The sludge amended plots had higher litter P levels, probablyas a result of the high P content of fescue grown on those treatments .Litter K levels were much lower than the K levels in fescue tissue.Plant K is water soluble and apparently was leached from the organicmaterial in the litter layer .Litter K levels in both the rock mix andsurface amendment experiments were similar.Conversely, litter Ca content was higher than the Ca content of fescuetissue. Within the plant, much Ca is contained in cellulose, which isresistant to decomposition. Calcium tends to become concentrated indecomposing organic matter.The soil material included in the litterlayer of these mine soils also had relatively high Ca content.The rockmix treatments did not have significantly different amounts of litter Ca,although the siltstone treatment contained higher levels of soil andtissue Ca.In the surface amendment experiment, the control and topsoiltreatments had the highest levels of litter Ca.Although these treatmentsdid not have higher tissue or soil Ca levels than the other surfaceamendment treatments, they did produce less biomass, so there may havebeen less decomposing tissue and more soil material included in the litterlayer.Litter Mg content was similar to tissue Mg content, and was notsignificantly different among treatments in either experiment.The metals Mn, Zn, Fe, and Cu were found in higher levels in thelitter layer than in fescue tissue (Table 30), presumably because of theinclusion of soil material in the litter layer. In the rock mix65

. Table 30. Metal content of tall fescue litter layers from the rockmix and surface amendment experiments, collected October 1987.Treatment Mn Zn Fe Cu---------------mg/kg--- -------------Rock Mix ExperimentSandstone (SS)1:1 SS:SiSSiltstone (SiS)1150.2a638 .3b602.2b50.73a48. 70a49. 72a6522a62lla4458b11.04a13 .48a13 . 33aSurface Amendment ExperimentControl (2:1 SS:SiS) 321 . 6ab 50.42a 6762abTopsoil (30 em) 325. 7ab 40.08a 4009bSawdust (112 Mgfha) 464.3a 49.73a 9382aSludge (56 Mgfha) 358.3ab 89.47b 5378bSludge (112 Mgfha) 229.6b 84 . 92b 4470b13 . 36abc10.12b12.76ab17.44c15.8lbcColumn means followed by different letters (by experiment)are significantly different, P=O . OS (Fisher's LSD) .66

experiment, Mn and Fe concentrations in litter followed trends similar tothose observed for tissue Mn and soil Fe levels.Litter Mn was highest inthe pure sandstone treatment, which had the highest fescue tissue Mnlevels, and litter Fe was lowest in the pure siltstone treatment, whichhad the lowest levels of extractable soil Fe. Litter Zn and Cu contentwere not significantly different among treatments.In the surface amendment experiment, the sawdust treatment had thehighest Fe and Mn levels. The sawdust treatment was more acidic than theother surface amendment treatments and apparently had higher levels ofplant-available metals in the soil. The topsoil treatment had the lowestlitter Fe and Cu content, probably because of the inclusion ofpreweathered topsoil material in the Oe horizon.The sludge treatmentshad higher litter Zn (and in some cases, Cu) content than the othertreatm~nts.Although the Zn content of fescue tissue was notsignificantly higher in samples taken from the sludge plots in 1987, theelevated litter Zn content may reflect Zn accumulation during previousyears, or inclusion of decomposed sludge in the litter layer .Pine Tree Performance as Affected by Rock Type.After five growing seasons on the rock mix experiment, the overallsurvival of the pitch x loblolly hybrid pines was 91%, and survival ofloblolly pines was 26%. Survival was unaffected by rock type. The hybridpines also grew better; the average hybrid pine height was 50% greaterthan the average loblolly pine height (1.58 m vs. 1.04 m). The pitch xloblolly hybrid pines are better adapted to the mountainous regions ofVirginia because of their greater tolerance of cold weather.67

Tree growth on the rock mix experiment was strongly affected by rocktype.Best growth occurred in the sandstone treatment, where the averagetree volume (1858 cm3) was almost five time greater than the averagevolume per tree in the siltstone treatment (322 cm 3 ; Torbert et al.,1990) . After the fifth growing season, loblolly pines were removed fromthe plots because they were performing poorly, and some additional hybridpines were thinned from the plots in order to ensure sufficient growingspace for the remaining trees.After the eighth growing season, rock type affects on tree growth werestill apparent (Table 31) .Trees in the sandstone plots were 60% tallerthan trees in the siltstone plots (3.58 m vs. 2.23 m) and average volumewas three times greater (7269 cm3 vs . 1783 cm3) .There was a strongpositive correlation between tree volume and the amount of sandstone inthe rock mix treatment (r-.96). The SS treatment had a significantlylower pH than the SiS treatment and there was a distinct inverserelationship between tree volume and minesoil pH (r- -.93). Therelationship between tree volume and pH was stronger than all othervolume/minesoil property relationships .Foliar levels of N, P, K, and Ca were not correlated with tree volumeand were not significantly different among rock mix treatments (Table 32).Foliar Mg levels were significantly higher in the siltstone than sandstoneor 2:1 SS/SiS treatments.Foliar N, P , K, Ca , and Mg levels for alltreatments exceeded the sufficiency levels of 12 g/ kg N, 1.0 g/kg P, 3.5g/kg K, 1.2 g/kg Ca, and 0 .7 g/kg Mg which are commonly accepted as68

Table 31. Average tree height, ground-line diameter , andstem volume of pitch x loblolly pine trees after eightyears in the rock mix and surface amendment experimentsTreatment Survival* Height Diameter Volume(%) (m) (em) (cm 3 )Rock Mix ExperimentSandstone (SS) 96 a 3.58 a 8. 6 a 7269 a2:1 SS:SiS 88 a 3.46 a 8.6 ab 6936 a1:1 SS:SiS 88 a 2 . 97 b 7.7 b 4972 b1:2 SS : SiS 90 a 2.92 b 7.3 b 4259 bSiltstone (SiS) 92 a 2.23 c 5.4 c 1783 cSurface Amendment ExperimentControl (2:1 SS:SiS) 100 a 2.45 be 6.7 be 3157 beTopsoil 90 a 2.65 b 7 .1 b 3840 beSawdust (112 Mgfha) 92 a 3.37 a 8.9 a 7239 aSludge (22 Mgfha) 90 a 3.05 ab 7.8 ab 5222 abSludge (56 Mgfha) 77b 2.94 ab 7.8 ab 5018 abSludge (112 Mgfha) 44 c 2.66 b 7 . 2 b 3967 beSludge (224 Mgfha) 10 d 2.26 c 5 .4 c 1787 c* Survival determined after five growing seasons.Means followed by the same letter, by experiment, are notsignificantly different (P-0.05, Fisher's LSD)69

~able 32. Nitrogen, P, K, Ca, Mg, and Mn concentrations in hybridpine foliage as affected by rock type after five years and surfaceamendment after three years.Treatment N p K Ca Mg Mn- - - - - g/kg - mg/kg -Rock Mix ExperimentSandstone (SS) 0.156 1.3 4 .4 2.3 1.2b 540 a2:1 SS:SiS 0.159 1.3 4.8 2.3 1.3 b 300 b1:1 SS:SiS 0 . 163 1.3 4 . 7 2.3 1.3 ab 270 be1:2 SS:SiS 0.166 1.4 4.7 2.4 1.4 ab 210 beSiltstone (SiS) 0.164 1.4 4 .6 2.6 1.6a 160 cSurface Amendment ExperimentControl (2:1 SS:SiS) 0.141 1.47 ab 5.8 a 2.3 c 1. 53 ab 198 aTopsoil 0.149 1.48 a 5.6 ab 2.2 c 1.45 b 156 aSawdust (112 Mgjha) 0.142 1. 29 b 5.3 ab 2.1 c 1.27 b 142 bSludge (22 Mgjha) 0 . 150 1.43 ab 5.4 ab 2.3 c 1.41 b 152 aSludge (56 Mgjha) 0 . 144 1. 39 ab 4. 7 b 2.8 be 1.43 ab 89 beSludge ( 112 Mgjha) 0.139 1. 26 ab 4.6 b 3.2 b 1. 25 b 66 cdSludge (224 Mgjha) 0.138 1.02 c 3.5 c 5.8 a 1. 81 a 32 d70

adequate levels of nutrition for loblolly pine (Allen, 1987; Fowells andKrauss, 1959; Stone, 1968 ; Wells and Crutchfield, 1973).Compared to agronomic crops, pines are better adapted and are moreproductive on somewhat acidic soils. The near-neutral pH of the siltstoneplots adversely affects pine performance, possibly by affecting micronutrientavailability.In this study, the average Mn concentration inpine needle tissue was 240% higher in the SS treatment compared to the SiStreatment (540 vs 160 mg kg-1), and there was a significant correlation(r- .77) between foliar Mn concentrations and tree volume.Manganesedeficiencies are infrequent in conifers on undisturbed acidic soils ,therefore sufficiency levels are not well documented.In a review ofmicronutrients in forest trees, Stone (1968) listed Mn levels of 300 to400 mg/kg as intermediate in range for loblolly pine. Values in thisstudy ranged from 160 to 540 mg/kg exceeding both ends of the intermediaterange. The highest levels in the sandstone plots may r epr esent luxuryconsumption, whereas the lower levels in siltstone plots plots appear tobe low based on Stone's review.Pine tree performance as affected by surface amendmentIn the surface amendment experiment, pine tree survival was adversel yaffected by increasing rates of sludge.Survival at the lowest rate ofsludge was 90% and was not significantly different from survival in thecontrol (100%), topsoil (90%), or the sawdust treatment (92%) .Poorestsurvival occurred in the 224 Mgjha sludge treatment (10%).Almost allmortality occurred during the first year. Pine seedlings are sensitive tosalt" concentrations and it is likely that high rates of nitrate and other71

~altsreleased by the sludge during the first year killed tree seedlings.The electrical conductivity of surface soil samples (0 to 20cm) collectedfrom the tree plots in 1985 was almost 4 times higher in the 224 Mg(hasludge plots than the 22 Mg(ha sludge plots (2.7 dS/m vs . 0.6 dS/m).Leaching during the first four years of this study probably reduced saltlevels in the sludge treatments to considerably less than the levelsduring the first year, when all mortality occurred.As in the rock mix experiment , the loblolly pines and some of thehybrid pines were thinned from the surface amendment experiment after thefifth season, and the study was measured after eight years .With theexception of the two highest sludge rates, the organic amendments in thisstudy were beneficial to tree growth (Table 31) . The best growth occurredin the sawdust treatments where tree volume averaged 130% more than treesin the control treatment (7239 vs 3157 cm3). The addition of topsoil didnot significantly increase tree growth over that in the control treatment(3840 vs . 3157 cm3).72

SUMMARY AND CONCLUSIONSThe overall findings of this study leave little doubt that carefullyselected overburden materials can be used to form productive topsoilsubtitutes in the Appalachian region. It must be noted, however , that allof the strata used in this experiment were non-acid forming, and that thepractice of using pre-mining acid-base accounting to screen suitablesubstitute materials must be strenuously adhered to. We believe thatmaterials with net acidities of less than five tons of lime requirementper acre will be generally suitable, as long as lime is applied at thetime of seeding to offset the net acidity present.As long asacid-forming materials can be avoided, it is likely that the pH of minesoils forming in overburden materials will remain considerably higher thanthat of associated. natural soils for long periods of time (more than fiveyears).Once an appropriate topsoil substitute material is placed at the finalreclamation surface and revegetated, it rapidly develops into a mine soilwith a distinct set of physical and chemical properties which are directlyrelated to its originating strata . The influence of originating rock typeon soil properties is most profound initially, but over the five-year bondrelease period, rock type influences appear to even out to some extent.The influence of rock type on pine performance was apparent througout theexperiment, while differences in fescue yield that were attributable torock type disappeared after two to three seasons .It does appear thatmixtures of coarse and fine texured strata are superior to pure spoils .Fine textured spoils , particularly those derived from siltstones and73

shales tend to have problems with surface crusting and internal drainage,and should be avoided if possible .It must be noted from a practicalstandpoint, however, that in many surface mining operations it is quitedifficult to mix two strata that do not occur together in the geologiccolumn.Distinct surface soil horizons, enriched with organic matter, occurwithin one year after revegetation, and subsurface horizonation isobservable within two to five years .Organic matter decompositon coupledwith carbonate dissolution and leaching, and fertilizer reactions combineto lower the surface pH fairly rapidly, but it appears to stabilize withinfive years , and may actually increase if sufficient carbonates are presentin the spoil. Distinct changes in surface soil texture, organic matterand extractable nutrient levels are observable in several years.Rapidgeochemical weathering and oxidation of the mine soil is evidenced byincreasing levels of extractable iron oxides with time. Therefore, theform and properties of mine soils cannot be viewed as static , which isfrequently our bias when working with weathered, natural soils.From a soil fertility standpoint, it appears that natural dissolutionand weathering reactions are sufficient to supply adequate Ca, Mg and K tothe plant community over the five-year bond release period.Likewise,micronutrient deficiencies were not observed, so natural weatheringrelease of these elements appears to be adequate . The ability of theweathering spoil to supply t hese elements is markedly reduced, however, ifthe topsoil substitute strata used was significantly pre-weathered andleached before mining.This commonly occurs in the zone of geochemical74

weathering below the natural soil profile, which may extend to 15 metersor more below the pre-mining surface in highly fractured and jointedstrata. This pre-weathered material is frequently used by the industry asa topsoil substitute because it blasts into a fairly fine textured spoil(low in coarse fragments) which is easy to handle and probably provides abetter water holding capacity per unit depth than harder, rockier spoils.The trade-off of water holding capacity versus long term nutrientavailability should be carefully considered, and overburden selectionshould depend on the intended post-mining land use.For forage crops,overburden which provides a relatively high level of available nutrientsshould be selected.For trees, which require less nutrients, overburdenthat provides maximum rooting volume and water holding capacity should bechosen.Our data leave little doubt that N-availability drives fescueproduction over the first several years of revegetation, and possibly theentire bond release period.Where legume establishment is not successful,or organic matter amendments such as sewage sludge are not employed, soilproductivity drops dramatically after the second growing season, andbiomass production in the bond release year is unlikely to meet releasestandards.While numerous other studies have indicated that Pavailability is likely to become limiting within the five-year bondrelease period, P did not appear to be limiting to fescue or pineproduction in this study.Our data do indicate, however , that over longerperiods of time (> 5 yr.), P does become reduced in availability andassociated with Fe-oxides weathering out of the spoil. This should notlead to nutrient deficiencies for pines, however, because of their known75

ability to utilize iron phosphates via mycorrhizal associations.Organic amendments, particularly appropriate rates of municipal sewagesludge produce superior mine soils, even in the complete absence offertilizer additions. Mine spoils are almost entirely lacking in organicmatter content, and do not appear to reach equilibrium levels of organicmatter accumulation through natural processes within the bond releaseperiod if organic amendments are not added. The benefits of sewage sludgeadditions include long-term nutrient supply, improved aggregation andwater holding, and probably a wide array of other factors such asmicrobial enhancement which were not measured in this study.We firmlybelieve that properly selected topsoil subtitutes amended with appropriaterates of sewage sludge will outperform natural topsoils in forageproduction throughout the five-year bond release period and beyond.Atlower rates of application (56 Mg(ha or less), this is also true forpines. Heavier rates of sludge inhibited the pine trees, but the 112 Mg(hasawdust amendment resulted in excellent pine growth.Obviously, the useof surface amendments must be predicated by the post-mining land use andthe desired vegetative cover.Regardless of the inherent fertility and physical properties of atopsoil substitute material, the most important single factor in itsoverall productivity is its effective rooting depth and associated totalwater holding capacity.Since most overburden materials contain a highcontent of coarse fragments , two to three feet of uncompacted mine soildepth is critical for long-term revegetation.This is best achieved byend-dumping the final reclamation surface with closely-spaced piles of the76

designated topsoil substitute, grading the final surface while the spoilis fairly dry, and then excluding all vehicular traffic from the area.This sequence is rarely followed today, and as a result the vast majorityof mine soils in the region contain severely compacted zones within thenormal rooting zone.In summary, we believe that, as long as potentially acid-formingmaterials are eliminated from consideration, carefully selected, graded,and amended overburden materials can successfully serve as topsoilsubstitute materials over and beyond the five year bond period.In theabsence of organic amendments, the establishment and maintenance of avigorous legume component in the forage stand is cruc i al.77

REFERENCESAllen, H.L. 1987. Forest fertilization - nutrient amendments, standproductivity, and environmental impacts. J. Forestry. 85:37-46.Barnhisel, R. and P.M. Bertsch. 1982. Aluminum. In A.L. Page (ed.) Methodsof Soil Analysis, Part II, ASA Monograph #9:275-300 , Amer.Soc. Agron.,Madison, WI.Bremner, J.M. and C.S. Mulvaney. 1982. Nitrogen-total. p. 595-624 . In A.L.Page (ed.) Methods of Soil Analysis, Part 2. Chemical and microbiologicalproperties. Agronomy Monograph No. 9. Am. Soc. Agron. Madison, Wis.Chapman, H.D. 1965. Cation-Exchange Capacity. In C.A. Black (ed.) Methodsof Soil Analysis, Part II, ASA Monograph #9:891-901, Arner.Soc. Agron.,Madison, WI.Day, P.R. 1965. Particle Fractionation and Particle Size Analysis . In C.A.Black (ed.), Methods of Soil Analysis , Part I. ASA Monograph #9:545-566.Amer. Soc. Agron., Madison, WI.Powells, H.A. and R.W. Krauss . 1959. The inorganic nutrition of loblollyand Virginia pine with special reference to nitrogen and phosphorus.Forest Science. 5:95-112 .Keeney, D.R. 1982. Nitrogen-availability indices. p. 711-733. In A.L. Page(ed.) Methods of Soil Analysis, Part 2. Chemical and microbiologicalproperties. Agronomy Monograph No. 9. Am. Soc. Agron. Madison, Wis .Mclean, E.O. 1982. Soil pH and Lime Requirement. In A.L. Page (ed.),Methods of Soil Analysis, Part II. ASA Monograph #9:199-224. Amer. Soc.Agron., Madison, WI.Mehra, O.P . and M.L. Jackson. 1960. Iron oxide removal from soils andclays by a dithionite-citrate system buffered with sodium dithionite.Clays and Clay Min. 7:317-327.Moss, S.A., J.A. Burger, and W.L. Daniels. 1989. Pitch x loblolly pinegrowth in organically amended mine soils. J. Environ. Qual. 18:110-115.Murphy, J. and J.P. Riley. 1962. A modified single solution method for thedetermination of phosphate in natural waters. Anal. Chern . Acta. 27:31-36.Nelson, D.W. and L.E. Sommers. 1982 . Organic carbon. p. 561- 573 . In A.L.Page (ed. ) Methods of Soil Analysis, Part 2 . Chemical and microbiologicalproperties. Agronomy Monograph No. 9 . Am . Soc . Agron. Madison, Wis .Olsen, S.R. and L.E. Sommers. 1982 . Phosphorus . In A.L. Page (ed. ),Methods of Soil Analysis , Part II . ASA Monograph #9: 403- 430, Arner. Soc.Agron., Madison, WI.Roberts, J.A. , W.L. Daniels, J.C . Bell, and J.A. Burger. 1988a. Earlystages of mine soil genesis in a Southwest Virginia l ithosequence. Soil .78

Sci. Soc. Amer. J. 52 : 716-723 .. Roberts, J .A. , W.L. Daniels, J.G . Bell, and J.A. Burger. 1988b. Earlystages of mine soil genesis as affected by topsoiling and organicamendments. Soil. Sci. Soc. Amer. J. 52: 716-723.Roberts, J.A. , W.L. Daniels, J.G. Bell, and D.C. Martens. 1988c. Tallfescue production and nutrient status on Southwest Virginia mine soils. J.Environ. Qual. 17: 55-61 .SAS Institute Inc. 1982. SAS User's Guide: Statistics, 1982 Edition. Gary,NG: SAS Institute Inc., 584p.Stone, E.L. 1968. Micronutrient nutrition of forest trees: a review. p.132-175. In Forest fertilization - Theory and practice. Tennessee ValleyAuthority, Knoxville TN.Thomas, G.W . 1982. Exchangeable Cations. In A.L. Page (ed.), Methods ofSoil Analysis, Part II. ASA Monograph #9:159-165, Amer . Soc . Agron. ,Madison, WI.Torbert, J.L., J.A. Burger, and W.L. Daniels. 1990 . Pine growth variationassociated with overburden rock type on a reclaimed surface mine inVirginia. J. Environ Qual. 19:88-92.Wells, G.G. and D.M. Crutchfield. 1973. Soil and foliar guidelines for Pfertilization of loblolly pine. U.S.D.A. Forest Serv. Res. Pap. SE-110.79

Site: Plot 1Parent Material: SandstoneAPPENDIX A:Mine Soil Profile DescriptionsClassification: Typic Udorthent, loamy-skeletal, mixed, mesic .Location: Powell River Project Area, Wise County, Virginia.Topography: Very gently sloping.Drainage: Well drained.Vegetation: Ky-31 tall fescue.Described by: K.C. Haering and W.L. Daniels, 9/11/89.A 0-7 em Dark yellowish brown (lOYR 4/4) gravelly sandy loam; weakfine subangular blocky structure; very friable; many fineand very fine roots; clear smooth boundary.AC 7 -17 em Dark yellowish brown (lOYR 4/6) very gravelly sandy loam;weak medium subangular blocky structure; very friable;common fine and very fine roots; clear wavy boundary;Cl 17-51 em Dark yellowish brown (lOYR 4/6) very gravelly sandy loam;massive, with some areas of weak subangular blocky andplaty structure; friable; common fine and very fineroots, especially along coarse fragment faces; verycompacted; clear wavy boundary.C2 51+ em Dark yellowish brown (lOYR 4/6) very gravelly sandy loam;massive; friable; few very fine roots; much lesscompacted than Cl, with bridging voids apparent betweenrock fragments.Notes: Most rooting ends in the Cl horizon, which wasdense and compacted. There appeared to be l ess coarsefragments in this profile than any of the others .80

Site: Plot 9Parent Material: SiltstoneClassification: Typic Udorthent, loamy-skeletal, mixed, mesic.Location: Powell River Project Area, Wise County, Virginia.Topography: Very gently sloping.Drainage: Well drained.Vegetation: Ky-31 tall fescue .Described by: K.C. Haering and W.L. Daniels, 9/11/89.A 0-9 em Very dark grayish brown (lOYR 3/2) very gravelly sil tloam; weak fine granular and subangular bl ockystructure; very friable; many fine and very fine roots,clear wavy boundary.AB 9-20 em Dark gray (lOYR 4/1) very gravelly silt loam; weakmedium subangular blocky structure; friable; many veryfine and fine roots; clear wavy boundary.Bw 20-36 em Dark gray (lOYR 4/1) and gray (lOYR 5/1) very gravellysilt loam; weak medium subangular blocky structure;friable; many very fine and common fine roots; dense andcompacted; clear wavy boundary.Cl 36-49 em Grey (SY 5/1) and dark gray (lOYR 4/1) very gravellyloam; massive; friable; common fine and very fine roots,especially on coarse fragment faces; dense andcompacted; clear wavy boundary.C249+ ernDark gray (lOYR 4/1) very gravelly loam; massive;friable; few fine and very fine roots; less compact thanCl, with btidging voids apparent between coarsefragments.Notes: The quantity and depth of roots in this profilewas greater than in the sandstone profile. There werealso more coarse fragments. The AB horizon was somewhatdense, but the Bw and Cl horizons are the zone ofcompaction in this profile. The Bw horizon was describedas such because of definite structure development, butis most likely not a true cambic horizon.81

Site: Plot 16Parent Material: 1:1 sandstone:siltstone mixture.Classification: Typic Udorthent, loamy-skeletal , mixed, mesic.Location: Powell River Project Area, Wise County, Virginia.Topography: Very gently sloping.Drainage : Well drained.Vegetation: Ky-31 tall fescue.Described by: K.C. Haering, 9/20/89.AACClC20-6 em6-28 em28-55 em55+ emDark brown (lOYR 3/3) grading to dark yellowish brown(lOYR 3/4) very gravelly sandy loam; weak finesubangular block structure; very friable; many fine andvery fine roots ; clear wavy boundary.Dark yellowish brown (lOYR 4/4) very gravelly sandyloam; weak medium subangular blocky structure; friable;many very fine and common fine roots; clear smoothboundary.Dark yellowish brown (lOYR 4/4) very gravelly sandyloam; massive, with patches of weak subangular blockystructure; friable ; common fine and very fine roots;dense and compacted; clear wavy boundary.Dark yellowish brown (lOYR 4/4) very gravelly sandyloam; massive; friable; few fine and very fine roots;much less compacted than Cl, with bridging voidsapparent.Notes: Weathered, stripped sand grains were apparent inthe top 2 em of the A horizon. Sand appears to havebeen concentrated there. Most roots were found in the Aand AC horizon, but roots extended down through thecompacted Cl horizon on coarse fragment faces. Thecompacted zone ended higher in this profile than in theother profiles . Distinct zones of sandstone andsiltstone weathering were observed in this profile.This was also apparent in the mixed SS/SiS pits of thesurface amendment experiment.82

Site: Plot 21Parent Material: Topsoil (30 em) over 2:1 sandstone:siltstone mix.Classification: Typic Udorthent, loamy-skeletal, mixed, mesic .Location: Powell River Project Area, Wise County, Virginia.Topography: Very gently sloping.Drainage: Well drained.Vegetation: Ky-31 tall fescue.Described by: K.C. Haering, 9/11/89.AACIIClIIC20-5 em Dark brown (10YR 4/3) gravelly sandy loam; weak finegranular structure; very friable; many fine and very fineroots; clear smooth boundary.5-18 em Dark yellowish brown (10 YR 4/6) gravelly sandy loam;weak fine granular and subangular blocky structure; veryfriable; common fine and many very fine roots; abruptsmooth boundary.18-55 ern Dark yellowish brown (lOYR 4/4) with patches of yellowishbrown (lOYR 5/6) very gravelly sandy loam; massive, withareas of weak platy and subangular block structure ;common fine and very fine roots; very compacted; clearwavy boundary.55+ em Dark yellowish brown (lOYR 4/4) very gravelly sandy loam;massive; friable; few fine and very fine roots; much lesscompact than IICl.Notes: There is an abrupt boundary between the two typesof parent material ("topsoil" and overburden) in thisprofile . The horizon below this boundary (IICl) was denseand very compacted.83

Site: Plot 22Parent Material: 2 : 1 sandstone:siltstone mix amended with sawdust.Classification: Typic Udorthent, loamy-skeletal, mixed, mesic .Location: Powell River Project Area, Wise County , Virginia.Topography: Very gently sloping.Drainage: Well drained.Vegetation: Ky-31 tall fescue.Described by: K.C . Haering, 9/11/89 .A 0-11 em Dark brown (lOYR 3/3) gravelly sandy loam, weak finegranular structure; very friable; many fine and very fineroots, clear wavy boundary.A/C 11-20 em Dark brown (lOYR 3/3) and dark yellowish brown (10 YR4/4) very gravelly sandy loam; weak fine granular andsubangular blocky structure; friable; common fine andmany very fine roots; clear wavy boundary .Cl 20-58 em Dark yellowish brown (lOYR 4/4) very gravelly sandy loam;massive; friable; few very fine and fine roots;compacted; clear wavy boundary.C2 58+ em Dark yellowish brown (lOYR 4/4) very gravelly sandy loam;massive; friable; few very fine roots; less compactedthan Cl, with bridging voids apparent.Notes: Stripped sand grains apparent in upper part of Ahorizon. The A horizon in this profile was thicker anddarker than those in the rock mix and topsoil-amendedprofiles, tonguing into the A/C along rock faces. Athick litter layer and root mat was observed. There wasless structure apparent in the Cl horizon than in theother surface amendment profiles .84

Site: Plot 26Parent Material: Control - 2:1 sandstone:siltstone mix.Classification: Typic Udorthent, l oamy -skeletal, mixed, mesic.Location: Powell River Project Area, Wise County, Virginia.Topography: Very gently sloping.Drainage: Well drained.Vegetation: Ky - 31 tal l fescue .Described by: K.C. Haering, 9/11/89.A 0-9 em Dark brown (10/YR 3/3) very gravelly sandy loam; weakfine subangular blocky structure; friable; common fineand very fine roots; clear smooth boundary.AC 9-29 em Dark yellowish brown (lOYR 4/3) very gravelly sandy loam;weak medium subangular blocky; friable; common fine andfew very fine roots; clear smooth boundary.Cl 29-72 em Dark yellowish brown (lOYR 4/4) very gravelly sandy loam,wi th patches of brownish yellow (lOYR 5/6) and yellowishbrown (lOYR 6/8) sandstone; massive; friable; few veryfine roots; compacted; clear wavy boundary.C2 72+ em Dark yellowish brown (lOYR 4/4) very gravelly sandy loam;massive; friable; few very fine roots; not as compactedas Cl.Notes: This profile appeared to have a larger proportionof siltstone than would be indicated by the rock mixture,and thus had greater structure development in the AChorizon. The A horizon appeared to be sandier than theother horizons , perhaps as a result of the removal offiner material b ecause of sparse vegetation. The rootmat in this profile was not as thick as those observed inthe other surface amendment profiles or the rock mixprofiles. The Cl horizon was very compacted.85

Site: Plot 34Parent Material: 2 : 1 sandstone:siltstone mix amended with 56 Mg/ha sewagesludge .Classification: Typic Udorthent, loamy-skeletal, mixed, mesic.Location: Powell River Project Area , Wise County, Virginia.Topography: Very gently sloping.Drainage: Well drained.Vegetation: Ky-31 tall fescue.Described by: K.C. Haering, 9/20/89 ,A 0-10 em Dark brown (10 YR 3/3) gravelly sandy loam; weak finegranular and subangular blocky structure; very friable;many fine and very fine roots; clear wavy boundary.AC 10-25 em Dark yellowish brown (lOYR 4/4) very gravelly sandy loam;weak medium subangular blocky structure; friable; commonfine and many very fine roots; clear smooth boundary.Cl 25-68 em Dark yellowish brown (lOYR 4/6) very gravelly sandy loam,with patches of yellowish brown (lOYR 5/6) sandstone;massive; friable; common very fine and fine roots,especially along coarse fragment faces; compacted;gradual wavy boundary.C2 68+ em Dark yellowish brown (lOYR 4/6) very gravelly sandy loam;massive; friable; few fine and very fine roots; lesscompacted than Cl with large (20 ern) bridging voids.Notes: A horizon has a thick, dense, root mat. Sandgrains were apparent in the upper part of the A horizon.The Cl horizon was dense and compacted.86