Residual effects of topsoil replacement depths and onetime application of organic amendments in natural gas wellsite reclamation

Transcription

1 Residul effets of topsoil replement depths nd onetime pplition of orgni mendments in nturl gs wellsite relmtion Frnis J. Lrney, Andrew F. Olson, nd Pul R. DeMere Agriulture nd Agri-Food Cnd, Reserh Centre, 43 1st Avenue South, Lethridge, Alert, Cnd T1J 4B1 (e-mil: Reeived 27 Mrh 212, epted 22 August 212. Cn. J. Soil. Si. Downloded from y on 2/7/18 For personl use only. Lrney, F. J., Olson, A. F. nd DeMere, P. R Residul effets of topsoil replement depths nd one-time pplition of orgni mendments in nturl gs wellsite relmtion. Cn. J. Soil Si. 92: The suess of relmtion on ndoned wellsites depends on their pity to reover nd sustin levels of soil qulity similr to those existing prior to soil disturne. A study looked t four (,, 1 nd %) topsoil replement depths (TRD) nd five mendments [ompost, mnure, lflf (Medigo stiv L.) hy, whet (Tritium estivum L.) strw, hek] in the relmtion of three nturl gs wellsites in Alert. In 27 (1 yr fter estlishment) the wellsites were re-smpled to exmine residul effets of relmtion tretments on soil properties. In 27, there ws no differene in SOC etween the, 1 nd % TRD tretments nd ll three were signifintly higher thn the % TRD y n verge of 18%. Therefore dding hlf the mount of topsoil (%) 1 yr previously used long-term improvement in SOC (vs. % TRD), ut dding more topsoil (1, %) did not produe further gins. Soil orgni C (- to -m depth) on the ompost nd mnure tretments (ross ll sites nd TRD tretments) ws signifintly higher (8%) thn strw, lflf nd hek tretments some 1 yr lter. Results show tht initil investment in orgni mendments for wellsite relmtion n hve residul effets on soil qulity. Key words: Soil relmtion, orgni mendments, topsoil, soil orgni ron, nturl gs wellsites Lrney, F. J., Olson, A. F. et DeMere, P. R Effets re siduels de l ouhe de remplement du sol de surfe et de l pplition unique d un mendement orgnique sur l resturtion des sites d extrtion du gz nturel. Cn. J. Soil Si. 92: Resturer les puits ndonne s de pend de l pite du site ` retrouver et à mintenir un sol d une qulite semlle ` elle du sol qui existit vnt l perturtion. Dns le dre d une e tude qui dure de 1997 ` 2, les uteurs ont exmine l inidene de qutre ouhes de remplement du sol de surfe (,, 1 et %) (CRS) et de inq mendements [ompost, fumier, luzerne (Medigo stiv L.), foin, pille de le (Tritium estivum L.), témoin] sur l resturtion de trois puits de gz nturel en Alert. En 27 (1 n pre` s l méngement), ils ont pre leve de nouveux e hntillons pour étlir l effet re siduel des tritements sur les proprie te s du sol. En 27, l onentrtion de rone orgnique dns le sol e tit identique pour les tritements de, 1 et % CRS, e qui e tit signifitivement plus e leve que l onentrtion relevée ve le tritement % CRS (18 % en moyenne). Pr onse quent, jouter l moitie du sol de surfe ( %) 1 ns plus toˆt permet d me liorer l onentrtion de rone orgnique à long terme (omprtivement à % CRS), mis il n y uune méliortion supple mentire qund on ugmente l e pisseur de l ouhe de sol de surfe dvntge (1 ou %). L quntite de sol orgnique (profondeur de ` m) s roıˆt signifitivement (8 %) ve l ddition de ompost et de fumier (tous les sites et tous les tritements CRS), omprtivement ` e qui se produit ve l ddition de pille ou de luzerne, ou ve le tritement te moin, pre` s 1 ns. Ces résultts indiquent que onifier d emle e le sol des sites ` resturer ve un mendement orgnique peut voir des effets re siduels sur l qulité du sol. Mots lés: Resturtion du sol, mendements orgniques, sol de surfe, rone orgnique du sol, puits de gz nturel As of My 212, Alert s oil nd gs infrstruture inluded over 22 ple wells (Energy Resoures Conservtion Bord 212). A typil wellsite is 1.4 h in re (exluding ess rods nd pipeline rights-ofwy). As wells re depleted nd ndoned over time, the wellsites, mny of whih re lesed from griulturl lndowners, need to e returned to equivlent lnd pility (Alert Environment 199, 28), i.e., to levels of prodution similr to those whih existed prior to soil disturne. Wellsites estlished efore 1983 were not mndted to retin topsoil for use in relmtion fter depletion nd ndonment. Topsoil ws often stripped nd trnsported offsite for relmtion purposes elsewhere, leving soil surfe with vstly depleted soil orgni mtter (SOM) pool nd no supply of stored topsoil. Sine SOM influenes lmost ll soil physil, hemil nd iologil properties, suess in lnd relmtion, lrgely depends on rereting surfe horizon with enough SOM to sustin net primry produtivity (Akl nd Ll 2). Suh surfe horizons my e hieved either y slvging topsoil (often n expensive proposition) or dding orgni mendments, or using omintions of oth strtegies. Orgni Arevitions: SE, stndrd error; SOC, soil orgni ron; SOM, soil orgni mtter; TRD, topsoil replement depth Cn. J. Soil Si. (212) 92: doi:1.4141/cjss

2 Cn. J. Soil. Si. Downloded from y on 2/7/18 For personl use only. 884 CANADIAN JOURNAL OF SOIL SCIENCE mendments hve een suessfully used in the remedition nd stiliztion of degrded soils round the world (Quilty nd Cttle 211). Lrney nd Angers (212) onluded from review tht orgni mendments re idel for kik-strting soil relmtion minly due to their effets on iologil ggregtion. However, implementtion of orgni mendments in relmtion senrios is onstrined y puli pereption, timesle, ost nd the potentil pollutnt urden of the orgni mendment itself (Jones nd Heley 21). A study onduted from 1997 to 2 exmined the effets of four (,, 1 nd %) topsoil replement depths (TRD) nd five mendment tretments (ompost, mnure, lflf hy, whet strw, hek) in the relmtion of three wellsites in south-entrl Alert (Lrney et l. 23, 2; Zvomuy et l. 26). Lrney et l. (23) looked t rop response to the vrious relmtion tretments. Of the 2 tretments (four TRD five mendments), the 1% TRD-ompost tretment rnked highest in relmtion pity (the ility to produe rop iomss), eing 19% higher thn the seline tretment (1% TRD-hek). The lowestrnking tretment overll, ws the % TRD-strw tretment, whih yielded 64% of the seline tretment. Crop yield responses to orgni mendments were lrger when the reipient soil ws lower in orgni mtter. Zvomuy et l. (26) found tht low C:N rtio mendments, prtiulrly ompost nd lflf, were most effetive in improving grin N onentrtion. Chnges in soil properties reflet the suess or filure of relmtion prties on ndoned wellsites. Lrney et l. (2) showed tht TRD tretment differenes were onsistent ross ll wellsites, with 3 to 32% higher SOC on the % TRD ompred with the % TRD. After 4 mo (June 1997Otoer 2), the verge mounts (n 3 wellsites) of C onserved ner the soil surfe (expressed s perent of initil C dded) were: ompost (691% SE) mnure (49 16% SE) lflf (28911% SE) strw (2396% SE). The ove results point to enhned rop performne nd soil qulity s result of relmtion tretments over the short-term durtion of the initil study (4 yr, 19972). However, very few studies hve ddressed the longevity issue of relmtion tretments. Wlton et l. (21) reported tht 32% of iosolids pplied to degrded rngelnd persisted s frgments 2 mm dimeter 18 yr lter. They hypothesized tht muh of the pplied mteril remined euse of the relitrnt nture of digested iosolids omined with soil environmentl onditions in rid eosystems. Soil hnges hve een reported 9 yr (White et l. 1997) nd yr (Wlle et l. 29) fter iosolids pplition. Sine questions remin out the longevity of the relmtion tretment effets (TRD, orgni mendments), we rried out follow-up study in 27 where we returned to the three wellsites, reloted the plots, nd olleted further set of soil smples. Our ojetive ws to exmine, 1 yr fter estlishment, the residul effets of the relmtion tretments on SOC, totl N, ville phosphorus nd nitrte-n. MATERIALS AND METHODS Study Sites nd Experimentl Design The study is desried in greter detil y Lrney et l. (23, 2). Briefly, three ndoned nturl gs wellsites (Strthmore, Hesketh nd Rosedle) were seleted in south-entrl Alert in the spring of The soils were Orthi Drk Brown or Blk Chernozems. Surfe soil texture ws lom to ly lom. The experimentl design ws split-plot, with TRD (%, %, 1% nd %) s the min tretment nd orgni mendment (ompost, mnure, strw, lflf nd hek) s the su-tretment, replited four times. Eh min plot ws 81 m in re with su-plots of 82 m. Topsoil Replement Depths nd Orgni Amendments Two-lift soil stripping ws rried out on ll three sites y n experiened opertor on ulldozer. This is the seletive reovery nd stokpiling of ll ville topsoil (mostly Ap horizon mteril) in the first lift nd good qulity susoil (mostly B horizon mteril, some Ap horizon mteril, miniml C horizon mteril) in the seond lift. Soils were redistriuted uniformly (susoil followed y topsoil) ross the sites to meet the required replement depth for topsoil of 6% (Alert Environment 199) of the ontrol soil (djent re undistured y wellsite tivities) depth. Topsoil depths (n1216 site 1 ) following soil redistriution were 9. (91.) m t Strthmore, 8. (9.8) m t Hesketh nd 9. (91.8) m t Rosedle, whih represented 69% of the topsoil depth on the ontrol re t Strthmore, 62% t Hesketh nd 82% t Rosedle. Therefore, ll sites met or exeeded the 6% required replement depth for topsoil under the relmtion riteri for pre-1983 wellsites (Alert Environment 199). It ws ssumed tht the depth of topsoil following soil redistriution represented the 1% TRD tretment. The % TRD tretment plots were hieved y removing the entire topsoil lyer (1%1% %). The % TRD tretment ws omplished y removing hlf of the topsoil lyer depth (1%% %) nd dding it evenly to rete the % TRD plots (1%% %). After TRD min plot tretments were estlished, mendments were pplied s one-time su-tretments in lte June/erly July 1997 s follows: (1) ompost derived from strw-edded ttle feedlot mnure; (2) fresh feedlot mnure; (3) strw (whet); (4) lflf hy nd () hek (unmended). Compost nd mnure were pplied t 4 Mg h 1 (dry wt), nd strw nd lflf t Mg h 1 (dry wt). Amendments were inorported with two psses of rotry ultivtor to 1 m depth.

3 LARNEY ET AL. * NATURAL GAS WELLSITE RECLAMATION 88 Cn. J. Soil. Si. Downloded from y on 2/7/18 For personl use only. Soil Mngement, Smpling nd Anlyses Spring whet ws the test rop t ll three sites for the initil 4-yr (19972) study. After hrvest in 1998 nd 2, soil smples were tken from eh plot to determine nutrient sttus. In fll 2, metl mrkers were uried t depth on the orners of eh replite t eh site nd their oordintes were reorded using glol positioning system nvigtion devie. From fll 2 to spring 27, the wellsites were frmed y the lndowners in the sme mnner s djent fields. At Strthmore, whet ws grown from 21 to 2, nol (Brssi npus L.) in 26 nd whet in 27, ll under minimum tillge. The Hesketh site ws under 3-yr whetwhetnol rottion with minimum tillge The Rosedle site ws seeded to tme hy [lflftimothy (Phleum prtense)smooth romegrss (Bromus inermis Leyss.) mixture] in 21, whih ws present t smpling in 27. None of the sites were summer fllowed or reeived ny form of orgni mendments sine those pplied in In 27, the metl mrkers were loted nd the originl plots re-stked nd soil smpled on My 1 t Strthmore, Sep t Rosedle nd Ot. 34 t Hesketh. At ll three smpling times (1998, 2, 27), soil ws otined t - to -m, - to 3-m nd 3- to 6-m depths. The three smpling times represented 1.3 yr (Fll 1998), 3.3 yr (Fll 2) nd1 yr (27) fter estlishment of the TRD nd orgni mendment tretments t eh site. Arhived ir-dry soil smples (Fll 1998 nd Fll 2) were retrieved from plsti storge totes nd nlyzed simultneously with the fll 27 smples. This minimized is due to lortory or opertor onditions. Anlyses were onduted on totl of 216 smples (3 smpling times 3 sites 3 depths 8 plots). Totl C nd N were determined y dry omustion using n utomted elementl nlyzer (Crlo Er, Miln, Itly), inorgni C y the method of Amundson et l. (1988), nd orgni C s the differene etween totl nd inorgni C. Aville P ws mesured olorimetrilly (Murphy nd Riley 1962) following extrtion y the modified Kelown method (Ashworth nd Mrzek 199). Extrtions for nitrte-n were mde using 2 M KCl nd determined olorimetrilly using n AutoAnlyzer II SC Colorimeter (Tehnion Instruments Corp., Trrytown, NY). Sttistil Anlyses All sttistil nlyses were performed using SAS (SAS Institute, In. 211). Soil properties were nlyzed using the MIXED proedure for repeted mesures (Littell et l. 1996) with site, mendment, TRD nd yer s vriles. Yer (n3: 1998, 2, 27) ws repeted mesures ftor while replite (n 4), replite site nd replite site TRD were rndom effets. After testing for outliers, pproprite ovrine strutures were seleted ording to the lowest Akike s Informtion Criterion (Littell et l. 1996). This nlysis llowed omprison of soil properties s ffeted y site, TRD, mendment, nd smpling time (yer) s well s twowy (site TRD, sitemendment, TRD mendment, siteyer, TRDyer, mendmentyer), 3-wy (site TRDmendment, sitetrdyer, sitemendment yer, TRD mendment yer), nd four-wy (site TRD mendmentyer) intertions. Lrney et l. (2) presented soil property results for 1998 nd 2 from this experiment. However the dt were nlyzed individully y site nd yer wheres the results presented in the urrent pper differ in the following respets: (1) new dt from 27 is inluded for omprison with 1998 nd 2 to exmine residul effets; (2) site nd yer re treted s vriles; (3) ll soil nlyses were onduted in the sme lortory run, i.e., rhived 1998 nd 2 smples were re-nlyzed longside 27 smples. Where signifint intertions our with site nd yer (e.g., sitetrdyer), the disussion fouses on effets in 27 ompred with 2 nd RESULTS AND DISCUSSION Residul Effets of Topsoil Replement Depths Soil orgni ron ws signifintly ffeted y site, TRD, mendment nd yer t the - to -m depth (Tle 1). However, these effets were qulified y signifint site TRDyer (P.2) effets, whih showed tht differenes in SOC due to TRD (ross ll mendments) were still pprent in 27 t ll three sites (Fig. 1), some 1 yr fter estlishment. At Hesketh in 27, the 1% TRD tretment hd signifintly higher SOC (26. mg kg 1 ) thn the, nd % TRD tretments (21.4 to 23.4 mg kg 1 ), whih ontinued the trend found in 2. At Rosedle nd Strthmore in 27, there ws no differene in SOC etween the, 1 nd % TRD tretments nd ll three (, 1 nd %) were signifintly higher thn the % TRD y n verge of 18% t eh site. Therefore dding only hlf the mount of topsoil (%) 1 yr previously ws enough to eliit long-term improvement in SOC over the % TRD, ut dding deeper mounts (1, %) did not use further improvements. Eight of nine TRD omprisons (Fig. 1) showed no signifint inrese in SOC due to ddition of % topsoil ompred to 1% topsoil. This supported the findings of Jgdmm et l. (29) who reported no inrese in SOC in the - to 1-m depth where topsoil hd een dded to existing undistured topsoil. The sitetrd yer effet (ross ll mendments) t - to -m depth showed signifint SOC rul (y 7.8 to 12.6%) etween 1998 nd 27 on the % TRD nd 1% TRD tretments t Hesketh nd on the % TRD t Rosedle, i.e., on three of the 12 omprisons (Fig. 1). On the remining nine omprisons, SOC in 1998 nd 27 were not signifintly different from eh other.

4 886 CANADIAN JOURNAL OF SOIL SCIENCE Tle 1. Effets of site, topsoil replement depth, mendment nd yer on SOC (- to -m nd - to 3-m depths), totl N (- to -m depth) nd ville P (AP - to -m depth) onentrtions OC (g kg 1 ) Totl N (g kg 1 ) AP (mg kg 1 ) m 3 m m m Cn. J. Soil. Si. Downloded from y on 2/7/18 For personl use only. Site Hesketh Rosedle Strthmore Topsoil replement depth (TRD) (%) Amendment Compost Mnure Strw Alflf Chek Yer P vlue Site B.1 z.1 z B.1 z.4 z TRD B.1 z.22 B.1 z.2 Amendment B.1 z.91 B.1 z B.1 z Yer B.1 z B.1 z B.1 z B.1 z SiteTRD SiteAmendment TRDAmendment SiteYer.7 z. z.84.4 TRDYer z.13 AmendmentYer B.1 SiteTRDAmendment SiteTRDYer SiteAmendmentYer TRDAmendmentYer SiteTRDAmendmentYer z Signifint effet qulified y signifint intertion. Mens followed y different letters re signifintly different ording to LSD (.). Mens seprtion informtion provided only if effet not qulified y signifint intertion effet. The mnipultion of SOC y different TRD tretments whih ws signifint in ll nine TRD omprisons t the - to -m depth (Fig. 1) extended to the - to 3-m depth in only two of nine TRD omprisons (Fig. 2). The % TRD hd signifintly higher (P.2) SOC thn the % TRD t Rosedle in 1998 (1.6 vs. 7. g kg 1 ) nd Strthmore in 27 (12.1 vs. 9.6 g kg 1 ), sine shllower lyer (inherently higher in SOC) would e smpled for the - to 3-m depth on the % TRD ompred with the % TRD due to the lk of topsoil. As with SOC, signifint (P.2) sitetrd yer effet (ross ll mendments) t -to -m depth showed tht differenes in totl N due to TRD were still pprent in 27 t ll three sites (Fig. 3) some 1 yr fter estlishment. At Hesketh in 27, the 1% TRD hd signifintly higher totl N (2.33 mg kg 1 ) thn the, nd % TRD ( mg kg 1 ). At Rosedle nd Strthmore in 27, s with SOC, there ws no differene in totl N etween the, 1 nd % TRD tretments nd ll three were signifintly higher thn the % TRD (Fig. 3) y n verge of 1619%. Therefore, dding only hlf the mount of topsoil (%) 1 yr previously ws enough to eliit long-term improvement in totl N over the % TRD, ut dding deeper mounts (1, %) did not use further inreses. None of the nine TRD omprisons (Fig. 3) showed signifint inrese in totl N due to ddition of % topsoil ompred with 1% topsoil. At the - to 3-m depth, totl N ws not signifintly ffeted y TRD or mendment (dt not shown). The site, mendment nd yer effets for ville P (- to -m depth) were qulified y signifint intertion effets (Tle 1). However, the TRD effet showed no intertion, whih ment tht ross ll sites,

5 LARNEY ET AL. * NATURAL GAS WELLSITE RECLAMATION 887 Orgni Cron, g kg Hesketh Rosedle Strthmore Orgni Cron, g kg Hesketh Rosedle Strthmore Cn. J. Soil. Si. Downloded from y on 2/7/18 For personl use only. Orgni Cron, g kg Yer % TRD % TRD 1% TRD % TRD Hesketh Rosedle Strthmore Topsoil Replement Depth, % Fig. 1. SiteTRDyer intertion effet (verged over mendments, P.2) on SOC onentrtion (- to -m depth): () TRD tretments ompred within yers; () yers ompred within TRD tretments. Mens followed y different letters re signifintly different ording to LSD (.). mendments nd yers, the % (1 mg kg 1 ) nd % (6 mg kg 1 ) TRDs hd signifintly lower ville P thn the % (7 mg kg 1 ) ut not the 1% (63 mg kg 1 ). Also, there ws no signifint differene in ville P etween the, nd 1% TRD tretments, likely euse the ddition of mendments (vlues re verged ross ll mendment tretments), prtiulrly ompost nd mnure, nelled out the effets of lk of topsoil on ville P. Additionlly, s with SOC nd totl N, the presene of extr topsoil (% TRD) did not signifintly inrese ville P onentrtion ompred with the 1% TRD. At the - to 3-m depth, ville P ws not signifintly ffeted y site, TRD, mendment or yer (dt not shown). The overll verge ville P onentrtion (ross ll sites, TRDs mendments nd yers) t 3 m ws 17 mg kg 1, sustntilly lower thn the verge of 62 mg kg 1 for the - to -m depth Yer % % 1% % Fig. 2. SiteTRDyer intertion effet (verged over mendments, P.2) on SOC onentrtion (- to 3-m depth): TRD tretments ompred within yers. Mens followed y different letters re signifintly different ording to LSD (.). Soil nitrte-n is very dynmi property, hnging rpidly with seson, fertilizer or mendment pplitions, nd rop growth stge. Therefore residul effets from TRD nd one-time pplitions of orgni mendments were not s prevlent s the other soil properties (dt not shown). While some effets of TRD on nitrte-n were pprent in the erly yers (Lrney et l. 2), residul effets in 27 were onfined to the - to -m depth t the Rosedle site where the % TRD (7. mg kg 1 ) ws signifintly higher thn the nd 1% TRD tretments (4.7. mg kg 1 ) ut not the % TRD tretment (6.9 mg kg 1 ). There were no Totl Nitrogen, g kg Hesketh Rosedle Strthmore Yer % % 1% % Fig. 3. SiteTRDyer intertion effet (verged over mendments, P.2) on totl N onentrtion (- to -m depth): TRD tretments ompred within yers. Mens followed y different letters re signifintly different ording to LSD (.).

6 Cn. J. Soil. Si. Downloded from y on 2/7/18 For personl use only. 888 CANADIAN JOURNAL OF SOIL SCIENCE signifint TRD effets on nitrte-n in 27 t the - to 3-m or 3- to 6-m depths. Residul Effets of Orgni Amendments A signifint (P.3) mendmentyer effet (ross ll sites nd TRD tretments) showed tht ompost nd mnure tretments hd signifintly higher SOC thn strw, lflf nd hek tretments in 1998 nd 2 nd remined so in 27, some 1 yr fter estlishment (Fig. 4). However, the mgnitude of the differene deresed over time. In 1997, verge SOC on the ompost nd mnure tretments ws 21.6 g kg 1 ompred with 18.8 g kg 1 for the strw, lflf nd hek tretments, differene of %. By 27, equivlent vlues were 21.3 g kg 1 for ompost nd mnure nd 2 Orgni Cron, g kg 1 Orgni Cron, g kg Yer Compost Mnure Strw Alflf Chek Amendment Compost Mnure Strw Alflf Chek Fig. 4. Amendmentyer intertion effet (verged over TRD tretments nd sites, P.3) on SOC onentrtion (- to -m depth): () mendments ompred within yers; () yers ompred within mendments. Mens followed y different letters re signifintly different ording to LSD (.) g kg 1 for strw, lflf nd hek, differene of 8%. This is lso demonstrted in Fig. 4 where SOC vlues for the ompost nd mnure tretments in 1998 were not signifintly different from those in 27. However, SOC vlues were signifintly higher in 27 thn in 1998 for lflf (2.1 vs g kg 1, 6% higher) nd hek (19. vs g kg 1, % higher). Applition of ompost nd mnure initilly oosted SOC levels, s mesured in 1998, while their stle C ws stored leving SOC levels reltively unhnged (Fig. 4) y 27. In ontrst, SOC levels on the lflf nd hek tretments were initilly lower in 1998 nd rued over time, s result of soil onservtion mngement prties on the sites, e.g., no-till seeding nd sene of summer fllow. Despite this rul, however, SOC levels on the lflf nd hek tretments remined signifintly lower thn ompost nd mnure tretments in 27 (Fig. 4). The mnipultion of SOC y ddition of mendments did not extend to the - to 3-m depth s denoted y non-signifint effet on SOC (Tle 1) where ll mendment tretments fell within the rnge of 11. to 11.8 g kg 1 (verged ross ll sites, TRDs nd yers). The improvement of SOC onentrtions y ddition of orgni mendments is well-doumented (Shresth et l. 29; Diono nd Montemurro 21). Applition of orgni mendments results in n immedite inrese in SOC, whih is generlly proportionl to the mount of C dded (Chntigny et l. 1999). There is lso evidene tht the SOC storge rte inreses more due to repeted mnure nd ompost dditions ompred with minerl fertilizers or other orgni mterils suh s strw (Mono et l. 28). However, in ses of high kground levels nd or high vriility, hnges in SOC following low or moderte pplition rtes my not e mesurle or detetle (Viud et l. 211). Averged over the three sites, C in the form of ompost ws dded t 7.8 Mg h 1 while tht dded in mnure ws 11.7 Mg h 1 (Lrney et l. 2). Cron dded s strw ws 7.4 Mg h 1 while tht s lflf ws 6.7 Mg h 1. Although C mss dditions were not dissimilr mong mendments, we deteted signifint SOC differenes (ompost, mnurelflf, strw) extending over period of 1 yr fter only single pplition of mendments. Cox et l. (21) lso reported tht ompost ws of gretest enefit in improving soil qulity on n eroded soil in Wshington ompred with strw or ol sh. The sttus of C on the deomposition spetrum is importnt in the ility of orgni mendments to enhne SOC levels. Compost- or mnure-c is more stle thn strw- or lflf-c. Most of the redily deomposle C hd lredy left the ompost nd mnure efore they were soil-inorported, leving mostly stle C, whih hd the ility to rise SOC levels. In ontrst, the greter prt of orgni C in strw nd lflf ws redily deomposle, reking down one soil inorported. While, the remining C ws ple of rising SOC levels on the lflf tretment

7 LARNEY ET AL. * NATURAL GAS WELLSITE RECLAMATION 889 Cn. J. Soil. Si. Downloded from y on 2/7/18 For personl use only. to 2.1 g kg 1 over 1 yr (Fig. 4), it did not inrese to the sme level (verge 21.3 g kg 1 ) s the ompost nd mnure tretments. Although Leroy et l. (28) reported differenes in deomposition/stility etween ompost- nd mnure-c, they ehved quite similrly over time in our experiment, in terms of indued hnges in SOC. Also, the hek tretment (Fig. 4), showed tht restortion of SOC levels in the sene of orgni mendment inputs ws possile nd mesurele, espeilly when promoted y ontinuous ropping under no-till mngement. Lrney et l. (29) lso showed rop yield reovery on soils sujeted to simulted erosion with no dded mendments (similr to the hek tretment in this experiment), lthough not to the sme level s non-eroded soils. Residul effets of mendments on totl N ontent mirrored SOC to lrge extent. However, mendment tretment did not intert with ny other effets (site, TRD, yer) s with SOC, mking interprettion more strightforwrd (Tle 1). Aross ll sites, yers nd TRDs, the ompost nd mnure mendments ( g kg 1 ) were signifintly higher thn lflf (1.91 g kg 1 ), whih ws in turn signifintly higher thn strw nd hek tretments ( g kg 1 ). On verge, over the 1 yr of the study, the ompost nd mnure tretments hd 7% higher totl N onentrtion thn lflf nd 11% higher thn strw nd hek tretments. Flvel nd Murphy (26) ontended tht soil C nd N yling re intrinsilly linked, nd the degree to whih soil mendments impt these yles depends on their qulity nd the quntities dded. The totl N dt showed tht the ility of ompost nd mnure tretments to oost soil N ontent lsted for t lest 1 yr (yer ws non-signifint). While higher initil mounts of totl N were dded s ompost (696 kg h 1 ) nd mnure (69 kg h 1 ) ompred with lflf (37 kg h 1 ), the ompost nd mnure-n ws likely in more stle slow-relese form thn tht in lflf, whih ws more redily deomposle (Lrney et l. 2). As well s dding the lowest mount of N (142 kg h 1 ), the lrge rte of strw inorportion (1617 Mg h 1 ) my hve immoilized N relese in the first yer fter inorportion. Zvomuy et l. (27) lso reported greter stility of ompost N thn lflf N in nother wellsite relmtion study in southern Alert. A signifint (P B.1) mendment yer intertion for ville P onentrtion (Fig. ) showed tht ross ll sites nd TRD tretments, the strw, lflf nd hek tretments (whih were not signifintly different from eh other) were signifintly lower thn the ompost nd mnure tretments in 1998 nd 2 (423 vs. 691 mg kg 1 ). In 27, the strw nd hek tretments (9 mg kg 1 ) were signifintly lower thn oth ompost (8 mg kg 1 ) nd mnure (68 mg kg 1 ), ut unlike 1998 nd 2, there ws no signifint differene etween the lflf Aville P, mg kg 1 Aville P, mg kg Yer Compost Mnure Strw Alflf Chek tretment (63 mg kg 1 ) nd the mnure tretment. In ll 3 yr, the ompost tretment showed signifintly higher ville P (verge 88 mg kg 1 ) thn the mnure tretment (67 mg kg 1 ). This my e relted to the higher rte of P initilly dded s ompost (22 kg h 1 ) ompred with mnure (site verge, 134 kg h 1 ). Rtes of P ddition were sustntilly lower with lflf (23 kg h 1 ) nd strw (1 kg h 1 ), whih would lso explin susequent differenes, ompred with ompost nd mnure tretments, on ville P levels over time. Lrney et l. (211) reported tht totl P onentrtions on desurfed soil ( m topsoil removl) remined signifintly higher 11. yr fter pplition of fresh, old nd omposted ttle mnure, nd hog or poultry mnure. Inreses in soil P Amendment Compost Mnure Strw Alflf Chek Fig.. Amendmentyer intertion effet (verged over TRD tretments nd sites, PB.1) on ville P onentrtion (- to -m depth): () mendments ompred within yers; () yers ompred within mendments. Mens followed y different letters re signifintly different ording to LSD (.).

8 Cn. J. Soil. Si. Downloded from y on 2/7/18 For personl use only. 89 CANADIAN JOURNAL OF SOIL SCIENCE ssoited with livestok mnure pplition re well doumented (Qin et l. 24; Chng et l. 2). The mgnitude of tretment differenes in ville P delined over time. For exmple, ville P on the ompost tretment ws two times higher thn tht on the hek tretment in 1998, flling to 1.6 times higher in 2 nd 1.4 times higher in 27. Amendment hnges over time (mendment yer intertion) re further illustrted in Fig., where the level of ville P ws signifintly lower on the ompost tretment in 27 thn in 1998 (8 vs. 91 mg kg 1 ), while on the mnure tretment there ws no signifint differene etween yers. In ontrst, ville P levels were signifintly higher on the strw (9 vs. 42 mg kg 1 ), lflf (63 vs. 49 mg kg 1 ) nd hek (9 vs. 4 mg kg 1 ) tretments in 27 thn in The ontrsting ehviour of ompost nd mnure (derese or stti) ompred with strw, lflf nd hek tretments (inrese) with respet to ville P over time my e prtly explined y greter removl of soil P y inresed rop iomss on ompost- or mnure-mended plots. Lrney et l. (23) reported tht iomss yields (verged over ll sites nd TRD tretments for the 4-yr period (19972) on ompost nd mnure tretments verged 16% higher thn strw, lflf nd hek tretments. This trend my hve likely ontinued during the intervening growing sesons efore soil smpling in 27. It should e orne in mind, tht ll plots t eh site reeived the sme pplition rte of fertilizer P during the initil tril, (17 kg h 1 seed-pled P in 1998, 1999 nd 2) nd one n only ssume tht the lndowners did not vry pplition rtes of fertilizer P ross eh site from 21 to 27. This would rule out differentil P fertilizer rtes s reson for the findings. Lrney et l. (2) reported higher levels of nitrte-n on the lflf tretment ompred with the other mendment tretments in 1998 t the - to -m, - to 3-m nd 3- to 6-m depths. However, y 27, the effets of mendment on nitrte-n hd disppered (dt not shown). Inlusion of legumes, in rop rottions or s green mnure plow-downs hs the potentil to inrese the risk of nitrte-n lehing (Cmpell et l. 26; De Jong et l. 29). Lnd mngers nd relmtion prtitioners onsidering the pplition of reltively unproessed N-rih soil mendment, like lflf, should e wre of potentil inreses in miroil tivity, nd relese of lrge mounts of nitrte-n into the soil system. Although our results showed tht this effet is short-lived, if rops re not in ple to interept this nitrte-n, potentil lehing elow the root zone ould our. Our results do not rule out the risk of lehing of lflf-derived nitrte-n to 6 m depth. However, sine the root zone of erels extends to 1.2 m depth, deeper movement of nitrte-n my not hve ourred. The study demonstrted residul effets of one-time pplitions of orgni mendments for nturl gs wellsite relmtion in southern Alert. At the - to - m depth, soil properties (SOC, totl N, ville P, nd to lesser extent nitrte-n) were signifintly ffeted y the individul vriles (site, TRD, mendment, yer) or their intertions. Residul effets were muh less prevlent t deeper soil depths. The SOC rnge mong TRD tretments (ross sites, mendments nd yers, - to -m depth) ws 17. to 21. g kg 1 (Tle 1) representing differene of 2%. The rnge mong mendments (ross sites, TRDs nd yers) ws 18.7 to 21.1 g kg 1 rnge of 11%, while tht mong yers (ross sites, TRDs nd mendments) ws 19.2 to 2.3 g kg 1, differene of 6%. Therefore, if soil relmtion prtitioners wnt to mnipulte SOC during wellsite relmtion, the order would e TRD mendmenttime in terms of rnge of influene, with initil TRD tretment three times nd initil mendment tretment two times more effetive thn the pssing of time (1 yr). The mnipultion trend for totl N ws very similr in the order TRD (differene of 21%) mendment (13%) time (1%). For ville P (- to -m depth) the order ws mendment (differene of 67%) TRD (47%) time (16%) showing tht unlike SOC, mendment (i.e., ompost or mnure vs. strw, lflf or hek tretments) ws more importnt in ditting long-term effets on ville P thn TRD. CONCLUSIONS Lnd degrdtion is n inresing prolem worldwide, nd orgni mendments my ply role in restoring eosystem helth nd servies. Suessful restortion hs food seurity enefits y wy of returning unprodutive lnd to its full yield potentil. This further renders environmentl enefits, s inreses in net primry produtivity will result in inresed C inputs to soil nd C sequestrtion. The livestok industry in Alert produes lrge volumes of mnure nd its return to the soil s ompost in relmtion senrios in the oil nd gs industry is good fit. Although there is mple work on short-term soil restortion trils, the long-term impt of orgni mendments on degrded lnd requires further explortion. Our results showed tht mintenne of SOC, N nd P levels in the topsoil over the long-term (1 yr) were possile. We ontend tht implementtion of soiluilding mngement prties (e.g. minimum tillge or no-till, ontinuous ropping, sene of summer fllow) on relmtion sites should sustin improvement of soil properties s result of orgni mendment ddition t the outset. ACKNOWLEDGEMENTS Reserh funding from EnCn Corportion, Clgry, Alert, is grtefully reognized. Vsile Klssen (formerly EnCn Corp.) filitted the initil field study (19972) nd Andre Bullinger (EnCn Corp.) the follow-up soil smpling (27). Tehnil ssistne ws

9 LARNEY ET AL. * NATURAL GAS WELLSITE RECLAMATION 891 Cn. J. Soil. Si. Downloded from y on 2/7/18 For personl use only. provided y Dniel Ygos nd Clrene Gilertson nd student help y Kevin Nkonehny, Jeremy Kreft nd Adele Kientz. This pper is Lethridge Reserh Centre ontriution no Akl, V. A. nd Ll, R. 2. Potentil of mine lnd relmtion for soil orgni ron sequestrtion in Ohio. Lnd Degrd. Devel. 11: Alert Environment Relmtion riteri for wellsites nd ssoited filities 199 updte. [Online] Aville: [212 Jul. 23]. Alert Environment. 28. Upstrem oil nd gs relmtion ertifite pplition guidelines. [Online] Aville: environment.lert./douments/upstrem_oil_nd_gs_re lmtion_ertifite_pplition_guidelines.pdf [212 Jul. 23]. Amundson, R. G., Trsk, J. nd Pendll, E A rpid method of soil ronte nlysis using gs hromtogrphy. Soil Si. So. Am. J. 2: Ashworth, J. nd Mrzek, K Modified Kelown test for ville phosphorus nd potssium in soil. Commun. Soil Si. Plnt Anl. 26: Cmpell, C. A., Selles, F., De Jong, R., Zentner, R. P., Hmel, C., Lemke, R., Jefferson, P. G. nd MConkey, B. G. 26. Effet of rop rottions on NO 3 lehed over 17 yers in medium-textured Brown Chernozem. Cn. J. Soil Si. 86: Chng, C., Whlen, J. K. nd Ho, X. 2. Inrese in phosphorus onentrtion of ly lom surfe soil reeiving repeted nnul feedlot ttle mnure pplitions in southern Alert. Cn. J. Soil Si. 8: Chntigny, M. H., Angers, D. A. nd Beuhmp, C. J Aggregtion nd orgni mtter deomposition in soils mended with de-inking pper sludge. Soil Si. So. Am. J. 63: Cox, D., Bezdiek, D. nd Fui, M. 21. Effets of ompost, ol sh, nd strw mendments on restoring the qulity of eroded Plouse soil. Biol. Fertil. Soils 33: De Jong, R., Drury, C. F., Yng, J. Y. nd Cmpell, C. A. 29. Risk of wter ontmintion y nitrogen in Cnd s estimted y the IROWC-N model. J. Environ. Mnge. 9: Diono, M. nd Montemurro, F. 21. Long-term effets of orgni mendments on soil fertility. A review. Agron. Sust. Devel. 3: Energy Resoures Conservtion Bord Alert drilling tivity monthly sttistis, My 212. Sttistil Series 9. [Online] Aville: st9/st9-urrent.pdf [212 Jul. 23]. Flvel, T. C. nd Murphy, D. V. 26. Cron nd nitrogen minerliztion rtes fter pplition of orgni mendments to soil. J. Environ. Qul. 3: Jgdmm, S., Ll, R. nd Riml, B. K. 29. Effets of topsoil depth nd soil mendments on orn yield nd properties of two Alfisols in entrl Ohio. J. Soil Wter Conserv. 64: 78. Jones, D. L. nd Heley, J. R. 21. Orgni mendments for remedition: putting wste to good use. Elements 6: Lrney, F. J. nd Angers, D. A The role of orgni mendments in soil relmtion: review. Cn. J. Soil Si. 92: Lrney, F. J., Akinremi, O. O., Lemke, R. L., Klssen, V. E. nd Jnzen, H. H. 23. Crop response to topsoil replement depth nd orgni mendment on ndoned nturl gs wellsites. Cn. J. Soil Si. 83: Lrney, F. J., Akinremi, O. O., Lemke, R. L., Klssen, V. E. nd Jnzen, H. H. 2. Soil responses to topsoil replement depth nd orgni mendments in wellsite relmtion. Cn. J. Soil Si. 8: Lrney, F. J., Jnzen, H. H. nd Olson, A. F Residul effets of one-time mnure, rop residue nd fertilizer mendments on desurfed soil. Cn. J. Soil Si. 91: Lrney, F. J., Jnzen, H. H., Olson, B. M. nd Olson, A. F. 29. Erosion-produtivity-soil mendment reltionships for whet over 16 yers. Soil Tillge Res. 13: Leroy, B. L. M., Shmidt, O., Vn den Bosshe, A., Reheul, D. nd Moens, M. 28. Erthworm popultion dynmis s influened y the qulity of exogenous orgni mtter. Pedoiologi 2: 139. Littell, R. C., Milliken, G. A., Stroup, W. W. nd Wolfinger, R. D SAS system for mixed models. SAS Institute, In., Cry, NC. Mono, S., Hth, D. J., So, D., Bertor, C. nd Grignni, C. 28. Chnges in hemil nd iohemil soil properties indued y 11-yr repeted dditions of different orgni mterils in mize-sed forge systems. Soil Biol. Biohem. 4: 686. Murphy, J. nd Riley, J. P A modified single solution method for the determintion of phosphte in nturl wters. Anl. Chim. At. 27: Qin, P., Shoenu, J. J., Wu, T. nd Mooleki, P. 24. Phosphorus mounts nd distriution in Sskthewn soil fter five yers of swine nd ttle mnure pplition. Cn. J. Soil Si. 84: Quilty, J. R. nd Cttle, S. R Use nd understnding of orgni mendments in Austrlin griulture: review. Soil Res. 49: 126. SAS Institute, In SAS/STAT 9.3 user s guide. SAS Institute In., Cry, NC. Shresth, R. K., Ll, R. nd Jinthe, P. A. 29. Enhning ron nd nitrogen sequestrtion in relimed soils through orgni mendments nd hiseling. Soil Si. So. Am. J. 73: Viud, V., Angers, D. A., Prnudeu, V., Morvn, T. nd Mensseri Aury, S Response of orgni mtter to redued tillge nd niml mnure in temperte lomy soil. Soil Use Mnge. 27: Wlle, B. M., Krzi, M., Forge, T. A., Broersm, K. nd Newmn, R. F. 29. Biosolids inrese soil ggregtion nd protetion of soil ron five yers fter pplition on rested whetgrss psture. J. Environ. Qul. 38: Wlton, M., Herrik, J. E., Giens, R. P. nd Remmeng, M. D. 21. Persistene of muniipl iosolids in Chihuhun desert rngelnd 18 yers fter pplition. Arid Lnd Res. Mnge. : White, C. S., Loftin, S. R. nd Aguilr, R Applition of iosolids to degrded semirid rngelnd: nine-yer responses. J. Environ. Qul. 26: Zvomuy, F., Lrney, F. J., Akinremi, O. O., Lemke, R. L. nd Klssen, V. E. 26. Topsoil replement depth nd orgni mendment effets on plnt nutrient uptke from relimed nturl gs wellsites. Cn. J. Soil Si. 86: Zvomuy, F., Lrney, F. J., DeMere, P. R. nd Olson, A. F. 27. Relmtion of ndoned wellsites with orgni mendments: effets on soil ron, nitrogen nd phosphorus. Soil Si. So. Am. J. 71: