The Influence of Vegetation in Riparian Filterstrips on Coliform Bacteria: I. Movement and Survival in Water

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1 o Reprinted from the Journl of nvironmentl Qulity Volume 29, no. 4, JulyAug. 2. opyright 2, ASA. SSA, SSSA 677 South Segoe Rd., Mdison, WI 5711 USA The Influence of Vegettion in Riprin Filterstrips on oliform Bcteri: I. Movement nd Survivl in Wter Jmes A. ntry,* Robert K. Hubbrd, Jnice. Thies, nd Jeffry J. Fuhrmnn ABSTRAT Swine (Sus scrof) wstewter ws pplied to three seprte 4 m wide x m long riprin filterstrips consisting of 2 m grss nd 1 m forest, 1 m grss nd 2 m forest, nd 1 m grss nd 2 m midencne (Pnicum hemitomon Schult.) in Southern Georgi during ech seson. Totl nd fecl coliform numbers in the pplied wstewter pulse did not decline s wter moved downslope regrdless of vegettion type or seson. The pulse of pplied wstewter did not move beyond 15 m in ny tretment in utumn or summer (dry sesons) nd only moved beyond 7.5 m in the 2 m grss1 m forest tretment in the summer. Totl nd fecl coliform numbers in soil wter nd shllow ground wter declined by pproximtely 1fold every 7 d for the first 14 d regrdless of vegettive tretment or seson. Soil temperture nd soil moisture correlted with totl coliform bcteri in both 1 m wells (r 2 =.89) nd 2. m wells (r 2 =.89), nd with fecl coliform bcteri in 1.5 (r 2 =.82) nd 2. m (r 2 =.76) wells. Animl production opertions my need to locte in wrm dry climtes so niml wste cn be pplied to lnds to help ensure enteric bcteri input to surfce nd ground wter will not occur. RIULTUR is mjor source of nonpointsource A pollution in lkes nd strems in the United Sttes (USPA, 1994). The increse in the size nd concentrtion of livestock units throughout the United Sttes nd the prctice of mnure disposl to griculturl lnds hs resulted in severl instnces of coliform bcteri in surfce wters exceeding the limits set by the USPA for recretionl wter qulity stndrds (USPA, 1998; Wlker et l., 199; Donnison nd ooper, 1989; Sorber nd Moore, 1987). When niml wste pplied to griculturl lnds nd subsequent surfce runoff or leching occurs due to overirrigtion or rinfll, contmintion of wter resources by enteric bcteri my result (ntry et l., 2). These sme bodies of wter re often used for sources of drinking wter nd for recretionl ctivities; therefore, elevted concentrtions of enteric bcteri pose potentil helth hzrd. Totl nd fecl coliform bcteri re sensitive nd commonly used indictors of bcteril pthogen contmintion of nturl wters. Their presence implies the potentil presence of microorgnisms tht re pthogenic to humns. Runoff nd ground wter from griculturl lnd tht hs hd niml wste pplied shows tht totl nd fecl coliform bcteri follow pttern: (i) Jmes A. ntry, USDAARS, orthwest Irrigtion nd Soils Reserch Lb., 79 orth 6 st, Kimberly, ID 844. Robert K. Hubbrd, USDAARS, Southest Wtershed Reserch Lb., P.. Box 946, Tifton, GA Jnice. Thies, ornell Univ., Dep. of rop nd Soil Science, 722 Brdfield Hll, Ithc, Y Jeffry J. Fuhrmnn, Dep. of Plnt nd Soil Sciences, Univ. of Delwre. ewrk, D Received 14 June *orresponding uthor (jentry@kimberly.rs.pn.usbr.gov ). Published in J. nviron. Qul. 29: (2). 126 higher numbers of coliform bcteri in wter during spring flows, (ii) lower numbers of coliform bcteri in wter during the summer dry period, (iii) higher numbers of coliform bcteri in wter fter pplying wstewter by irrigtion or fter dditionl mnure disposl, nd (iv) rpid decline of bcteri counts once mnure ppliction is hlted (Frser et l., 1998; Howell et l., 1996; Drling nd olthrp, 197; Buckhouse nd Gifford, 1976). Severl investigtors found tht fecl coliform numbers declined rpidly when trnsported through dispersed soils, indicting tht bcteril pollution occurs minly by trnsport vi wter through soil mcropores (AbuAshour et l., 1998; Howell et l., 1996; Huysmn nd Verstrete, 199; Buckhouse nd Gifford, 1976; Kunkle, 197). Riprin vegettion cts s nturl filter nd removes nutrients nd other contminnts through both ground nd surfce wter pthwys (Hubbrd et l., 1998; Snyder et l., 1998, Jordn et l.,.199; Lowrnce et l., 1984). Peterjohn nd orrell (1984) estimted n nnul net removl of 45 kg h ' from subsurfce wters moving out of fertilized crop lnd through 5 m of riprin forest. They lso reported substntil decreses in prticulte orgnic nd prticulte P in surfce wters. Riprin filterstrips provide n excellent sink for nutrients entering strems from surrounding griculturl lnds. However, there hs been little reserch on the effectiveness of forest riprin filterstrips to protect strem wters from coliform bcteri. The compnion study (ntry et l., 2) found tht lnd ppliction of swine wste to riprin vegettion incresed totl nd fecl coliform concentrtions in the to 5, 5 to 15, nd 15 to cm soil lyers from 1 to 1fold. oyne et l. (1995), Wlker et l. (199), nd Young et l. (198) concluded tht 1m wide grss filterstrips cn reduce the mount of fecl coliform bcteri in runoff by s much s 7%. The objective of this study ws to determine the effectiveness of forest nd grss vegettion growing in riprin filterstrips in filtering totl nd fecl coliform bcteri from surfce nd ground wter in different climtic conditions. MATRIALS AD MTHDS Site Description Plots were locted t the Animl Science Reserch Frm t the ostl Plin xperiment Sttion in Tifton, Georgi. The site included grssed re tht hd formerly been the lowest end of psture for beef cttle (Bos turus), n djcent downslope riprin forest with slsh pine (Pinus elliottii ngelm.), nd ccompnying underlying shrubby vegettion (Hubbrd et l., 1998). The soil of the grssed re ws Tifton lomy snd (finelomy, kolinitic. thermic Plinthic Kndiudults) while the riprin forest re ws n Alph lomy snd (lomy, silicious, thermic Arenic Plinthic Plequults)

2 TRY T AL: IFLU F VGTATI I RIPARIA FILTRSTRIPS: I 127 LGD MAIDA GRASS RIPARIA FRST PLT IDTIFIATI SURFA TUR LI (ASSUMD LV. I MTRS) SAL 1 2 meters Fig. 1. Grss riprin filterstrip tretments. or n intergrde between it nd Tifton lomy snd. These soils re underlin with plinthite nd Miocene ge mterils of very low permebility. In the plinthic soils of the Tifton Uplnd, 99% of infiltrting wter moves downslope s shllow lterl flow (Hubbrd nd Sheridn, 198). The slope t the site rnged from 1.5 to 2.%. Three different vegettion types were used for the study (Fig. 1 nd 2). Vegettive tretments were (i) 2 m grss buffer drining into 1 m existing forest riprin zone vegettion, (ii) 1 m grss buffer drining into 2 m existing forest riprin zone vegettion, nd (iii) 1 m grss buffer drining into 2 m midencne. Midencne is species recommended for constructed wetlnds. The purpose of midencne ws to see if wetlnd plnt species other thn trees nd understory vegettion would be effective in reducing survivl of totl nd fecl coliform bcteri compred with grss nd forest vegettion. Midencne ws plnted s rhizomes during the summer of 199. Three or four cuttings of the grssed zone were mde ech summer nd the biomss ws completely removed from the plots. Two cuttings (t pproximtely cm height) were mde of the midencne during the summers. Midencne is used s forge in Florid, so cutting nd removl of the midencne biomss ws used to simulte potentil cutting of this plnt for hy by niml producers. ostl bermud grss [ynodon dctylon (L) Pers; cv. Tifton 78] ws plnted in the grssed portion of the plots. During the fll of 199, hettolernt tll fescue (Festuc rundince Schreb.; cv. Georgi 5) ws plnted s perennil winter cover in the grssed portion of the plots. During the winter of , crimson clover (Trifolium incrntum L.) ws seeded on the plots, since the fescue hd not performed well in terms of cover during the previous winter ( ). The forested prt of the plots hd slsh pine tht were 8 yr old nd pproximtely 1 m tll by the end of the study in In this study grss ws cut to 1 cm height prior to ech ppliction of swine wste, while midencne grew to height of pproximtely cm in spring nd 2 m in summer. Plot Design The overlnd flow riprin buffer plots were ech 4 m wide nd m long nd were positioned on the lndscpe ccording to contour, so tht flow of the wstewter downslope would be s uniform s possible (Fig. 2). The sides of ech plot were bounded with plstic borders tht extended 15 cm bove ground nd 15 cm below ground. An erthen berm t the top of ech plot prevented surfce runoff entering from upslope of the plot. At the top of ech plot gted pipe mde of

3 128 J. VIR. QUAL.. VL. 29. JULYAUGUST 2 WAST TAK SLTTD PIP o q q q q q q q q q q H l q q q q q q q q q q + n GRASS RIPARIA FRST MAIDA FLUM H SIL LLTI SITS Fig. 2. Site digrm of swine wste grssriprin filterstrip plots. q SUTI LYSIMTRS,.5 AD 1. M SURFA RUFF LLTRS WLLS, 1.5 AD 2. M plstic ws used to pply wstewter. Suction lysimeters were plced in pirs t depths of.5 nd 1. m t four positions on trnsect from the wstewter ppliction pipe downslope to the bottom of ech plot (Fig. 2). The suction lysimeters were constructed of.8 cm dimeter (schedule 4) PV pipe with porous cups on the end. penings in the porous cups of the PV pipe were 2.9 p.m dimeter, lrge enough for bcteri to pss through. A vcuum system ws pplied to the lysimeters for pproximtely 12 h prior to collection of the smples. Wells were constructed of 5 cm dimeter (schedule 4) PV pipe nd hd 15 cm of slotted well screening t the bottom. A peristltic pump ws used to collect wter smples from the suction lysimeters nd ground wter wells. The suction lysimeters nd wells were completely evcuted during the smpling process to ensure tht wter for the next smpling would be fresh ground wter. The individul plots were positioned on the lndscpe to minimize crosscontmintion of the shllow ground wter nd vegettive tretments (Fig. 2). Wstewter flowed from n individul tnk bove ech plot into the gted pipe nd then downslope. The pipe gtes were spced 46 cm prt nd were djusted on ech plot so tht overlnd flow would begin downslope movement s uniformly s possible (Fig. 2). Depending on soil moisture nd vegettive conditions, wstewter flowed over onehlf to twothirds of ech plot during ppliction. Wstewter ws not pplied during rinstorms or if it ppered tht rinfll ws imminent. During the wet winter nd spring months when the soil ws nerly sturted. the wstewter ws pplied slowly, to minimize ny potentil for the wste to exit the plots vi overflow of the plstic borders. At other times the wstewter ws pplied s quickly s the tnks would drin completely, resulting in ppliction times of pproximtely 1 min. Wstewter The study ws implemented using swine lgoon wstewter from the tretmentstorge system t the University of Georgi ostl Plin xperiment Sttion swine unit t Tifton, Georgi. The unit mintined n inventory of 5 to 55 hed of swine during the course of the study. The lgoon system consisted of three lgoons, in series. The primry lgoon (12 X 46 m) dischrged into secondry lgoon (15 X 1 m), from which the liquid ws pumped bck into the brns (18 L min ') for flushing wste. The secondry lgoon dischrged into holding lgoon (18 x 7 m) tht ws used s the source of the wstewter for the study. Fetures of the lgoon system hve been further described (Hubbrd et l. 1998; ewton nd Hydon, 1985). ight hours prior to ppliction, liquid wste ws pumped pproximtely 76 m from the holding lgoon into 2 m dimeter x 1.5 m high plstic holding tnks locted t the upper end of ech plot (Fig. 2). Wstewter ppliction consisted of 257 L, from two tnks, per plot s one ppliction ech seson, which is typicl mount of niml wstewter pplied to site to meet crop demnds (Hubbrd et l. 1998). Totl coliform numbers in source wstewter rnged from 4.92 x 16 to 1.5 X 15 colonies 1 ml wter". umbers of fecl coliform bcteri in source wstewter rnged from 15.8 x 15 to 7. x 1 5 colonies 1 ml wter'. Anlyses of

4 TRY T AL.: IFLU F VGTATI I RIPARIA FILTRSTRIPS: I 129 wstewter smples collected weekly during the study showed verge concentrtion of 16 mg L1, with most of the in the H; form. itrte concentrtions in the wstewter rnged from less thn 1 mg to 2 mg L1 with men of mg L xperimentl Design The study ws rrnged in completely rndom fctoril design consisting of filterstrips with three vegettion types, climtic periods (seson), distnce from inflow source, nd depth of soil wter nd ground wter (Kirk, 1982). ch tretment ws replicted three times. Wstewter ws pplied s single pulse in winter, spring, summer, nd utumn hving four distinct climtic conditions (described below). Soil wter nd ground wter ws collected t four distnces from the wstewter inflow source. Totl nd fecl coliform bcteri were smpled in winter (wetcool period; 1428 Jnury), spring (wrmwet: 16 Mrch), summer (hotdry; 621 July) nd utumn (wrmdry; 1125 ovember) In winter soil temperture rnged from 1 to 14 nd soil moisture rnged from 1.8 to 2.8 g kg soil ', in spring soil temperture rnged from 17 to 22 nd soil moisture rnged from 1.5 to. g kg soil 1, in summer soil temperture rnged from to 45 nd soil moisture rnged from.1 to.7 g kg soil 1, nd in utumn soil temperture rnged from 1 to 18 nd soil moisture rnged from. to 1.1 g kg soil '. Ground wter temperture vried from 1 in winter to 22 in spring. Ground wter temperture in the 1.5 nd 2. m wells did not vry pprecibly mong filterstrip vegettion types in ny seson. There ws no ground wter in the 1.5 or 2. m wells during the summer smpling period. Smple ollection Soil wter ws smpled from ech lysimeter nd shllow ground wter ws smpled from ech well. Smples were nlyzed for totl nd fecl coliform bcteri 2 to 4 d prior to ech wstewter ppliction. Ground wter ws lso smpled in three res of grss nd forest vegettion t nerby site tht ws neither grzed nor hd niml mnure pplied to it s control (Lowrnce et l., 1998). Five seprte smples were collected from ech wstewter ppliction tnk (input) immeditely prior to wstewter ppliction. Surfce runoff smples were collected from the pulse of pplied wstewter flowing over the soil surfce t distnces of 7.5, 15., 22.5, nd. m from the ppliction pipe. Soil wter (lysimeters) ws smpled t.5 nd 1. m depths nd shllow ground wter (wells) ws smpled through wells t 1.5 nd 2. m depths t 5, 1, 2, nd m from the inflow source. Survivl of totl nd fecl coliform bcteri in ech fctoril combintion of vegettion ws determined in the pulse of wstewter s surfce flow on the dy of ppliction (Dy ), soil wter from suction lysimeters t 2 to 4 d prior to wstewter ppliction, nd t 1,, 7, 14, nd 9 to 12 d fter wstewter ppliction. Shllow ground wter ws smpled 2 to 4 d prior to wstewter ppliction nd t 7, 14, nd 9 to 12 d fter wstewter ppliction. Smple Anlysis Wter in suction lysimeters nd ground wter wells ws collected with peristltic pump into sterile 5 ml glss continers nd trnsported t mbient temperture to the Agriculturl Reserch Service Southest Wtershed Reserch Lbortory in Tifton, GA. Smples were stored t mbient tempertures nd processed within 4 hr of collection. Totl nd fecl coliform bcteri were nlyzed with the membrne filter technique (Greenberg et l., 1992). Preliminry smples of the pulse of pplied wstewter, soil wter, nd shllow ground wter were tken to obtin the dilution tht would grow pproximtely 2 to 2 totl or fecl coliforms on ech filter. A 1 ml of smple from ech finl dilution ws vcuumfiltered through sterile.45 p.m filter nd plced on mndo LS medium to determine totl coliform bcteri or mf medium to determine fecl coliform bcteri. Totl nd fecl coliform bcteri were incubted t 9.5 ±.2 nd 44.5 ±.2 respectively for 24 h. Three colony types of both totl nd fecl coliform bcteri from ech smple dte were identified by ftty cid nlysis using the ARB librry of the Microbil Identifiction System (ewrk, D). Sttisticl Anlyses All dependent vribles were tested for norml distribution. Dt were nlyzed by mens of nlysis of vrince (A VA) procedures for completely rndom design with Sttisticl Anlysis System (SAS Institute, 1996). umbers of totl nd fecl coliform bcteri were log trnsformed to chieve norml distributions. Sttisticl comprisons were mde of totl nd fecl coliform bcteri by vegettion type X seson x time since ppliction. Residuls were eqully distributed with constnt vrinces. Differences reported throughout re significnt t p.5, s determined by the Protected Lest Squres Mens test (Kirk,1982; Snedecor nd ochrn, 198). orreltions were determined with soil temperture nd moisture s independent (x) vribles nd totl or fecl coliform bcteri s dependent (y) vribles. Totl nd fecl coliform bcteri re reported in untrnsformed numbers. RSULTS Totl nd fecl coliform numbers in the wstewter source immeditely prior to ppliction were usully 1fold higher thn in the pulse of pplied wstewter t 7.5, 15., 22.5, nd. m from the inflow pipe on the dy of wstewter ppliction regrdless of vegettion type or seson. Totl coliform numbers in source wstewter rnged from 4.92 x 16 colonies 1 ml wter' to 11.6 x 16 colonies 1 ml wter'. umbers of fecl coliform bcteri in source wstewter rnged from 2.9 x 15 colonies 1 ml wter' to 15.8 x 15 colonies 1 ml wter'. The pulse of pplied wstewter moved s surfce flow overground to distnce of. m in ll tretments in the winter nd in the 2 m grss1 m forest tretment in spring. The pulse of pplied wstewter s surfce flow did not move beyond 15 m in ny tretment in utumn or summer (dry sesons) nd only beyond 7.5 m in the 2 m grss1 m forest tretment in summer. Popultions of totl nd fecl coliform bcteri in the pulse of pplied wstewter did not decline s wter moved downslope regrdless of vegettion type or seson of the yer. The generl liner models procedure indicted tht there ws no significnt difference in counts of totl nd fecl coliform bcteril numbers smpled in soil wter (lysimeters) t.5 m nd soil wter (lysimeters) t 1. m depths in shllow ground wter (wells) t 1.5 m nd nd in shllow ground wter (wells) t 2. m regrdless of vegettive tretment, distnce from the inflow source,

5 121 J. VIR. QUAL., VL. 29, JULYAUGUST 2 Y ey.c s z el g co r. T1 fttt fff g ttt xxxx XxXx ul s 4.2 vs un os eel tg D rn r. et Soi A r4 V) e4 r. v.,1 e4.cauu r4 Voce r n 'e1 e4.. l 1. 1n1 en top en V) R V V. 2: v. r. V1 11,1 r. v. en. h xxxx,n : 2b 2: el P:... xxxx xxxx en M os V),s 1,1 V) V) V Ṅ. I I A: A:. J: JD AD AZ JD 2: 2 v. w. v..1.1 Wt 4:r ^1,? ^1 17: S; RR,t;..7; RR =1 Ri V G GP GI R TS _g ID ID ID ID ID 11 xxxx xxxx xxxx Aet R R 't 't "I,R e4 et : 5; cy r. WI A rn vd ee ev.1 A T V: e4 et en...i v. SS. 7 ID 1. X XX X R R R R.S V : WI c'e r e) MI ' VI P n :.V.1 1 r rd X h V) )e : le ). J.) A xxxx enr VI tv) I. J., 1: " v. V. r. X XXX z c es SI 4: 1:1 1:1 I: 17 1:1 12 I: I: 47 V th X xxxx xxxx xxxx '? c: c: c: c? 4? 4? 4? `4.' : VT 4:1 it AT V Sd Ir S 1n1 S 1n1 xxxx xxxx xxxx U, 4?.1 '? r: ei 4 4 gt : A (M1 r.1 g. =, LV [ vd 17) R VI L, li; rn. s g 91.2 $o r '"I' *l I To cr os To.6 c mn1 tt,? w.. v. r. r. v x xxx xxxx xx xx e SP e A A A, ' I vi s, I en et n el eo r ev en ro A.= A u ul nn c.1 r. r* w. v. et et el et cd r; bpeg eg eg er fftg ft? g P D V V. w* 1.* w. vm v. 1.. rm pm rd X X xxx I i Men r; > un un tn /* 1 Ir. fo1 e4 r. e4 f4 fn ttf P Ir '1:1 7 xxxx 41 c es VI S D cn c4 c, en d en.r en A r. S S ' r. w. v..1 r. r1 r* r..1 v. v. r. X X X XXX v) * A R r; r; q> et. s p.14 e4 r M P P P.n D c: A.n c: D D Un D D A r. r4 er e4 en ee s X X f r.1 X fp Y s.1 l S. rc ST P,1 q. xxxx xxxx xxxx "1 e. hf1,1 c A. A. u,. r. v. r. XX X X J V cr wl R el MI V V.. v. v. win fin eo c: x: ZAM* SI s P 1 111iSe 1n1 VP ; o o.. AA Z rg thv ehl4.2 " v v..1 r XXXx xxxx XxxX ei c.'? el c> D.n, el r. e: I'm. re) r. g r e'en en rri cc r..j 4 I, ev SIP P V GS P v1 In1 '4: 4? 4? 4? gg egg 1* 1*,1 D D D un D D D un D D A un D D gk Mr1 v. e4 cv v = 17, g"'" to. 1 g UU V 1./ s.c. V "e, r... 7cec,. 1. v. v. v. xxxx xxxx xxxx et wri el s g n o = p e 4 ) 1= 61 Q A 4, is Ig V 2 e ft I o, 4 5 is c ; 111! Lt. 114, P 7 s rz, g P , 44 s es' (..7 Sr",1 ** ^ 6i q tr 6, :11 r. p 1 4+ ' A efk = 'I; Too ' cut I cy ) 4,

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7 1212 J. VIR. QUAL VL. 29, JULYAUGUST 2 Totl oliform Bcteri Fecl oliform Bcteri _16 5 oo ; 4 Z e. 5 g g, " Kg wter / Kg soil Temperture () Fig.. Popultions of totl (left grph) nd fecl (right grph) coliform bcteri in 1.5 in wells in riprin soils. Popultions of totl coliform bcteri in ground wter in 1.5 m wells were explined by the following polynomil regression with ground wter temperture (WT) nd soil moisture tken t 6 to cm deep (SM). Popultions of totl coliform bcteri = (WT).497 (WT) (WT).568 (SM) 4.75 (SM) (SM)', r 2 =.89 (p <.1). Popultions of led coliform bcteri = (WT).428 (WT) (WT).769 (SM) +.74 (SM) (SM), r 2.82 (p <.1). 5 or seson of yer. Therefore, totl nd fecl coliform bcteril numbers will be discussed with regrd to distnce from inflow x vegettive tretment X seson of yer (Kirk, 1982; Snedecor nd ochrn, 198). Totl nd fecl coliform numbers in soil wter (lysimeters) prior to smpling, which corresponded to 9 to 12 d since the wstewter ppliction, were slightly higher in the 2 m grss1 m forest filterstrip thn the 1 m grss2 m forest filterstrip in both winter nd spring, regrdless of distnce downslope from the inflow pipe or lysimeter depth (Tble 1). Totl nd fecl coliform numbers were usully higher in soil wter smpled from the lysimeters t 5 nd 1 m thn soil wter smpled t m from the inflow point regrdless of vegettive tretment, seson of the yer, or lysimeter depth. Totl nd fecl coliform numbers in soil wter (lysimeters) declined by pproximtely 1fold every 7 d for the first 14 d in winter nd spring regrdless of vegettive tretment. Totl nd fecl coliform numbers in shllow ground wter (wells) t 2 nd meters from the inflow pipe were slightly higher in the 2 m grss1 m forest filterstrip thn the 1 m grss2 m midencne filterstrip nd 1 m grss2 m forest filterstrip in winter, spring, nd utumn regrdless of well depth (Tble 2). umbers of totl nd fecl coliform bcteri were usully higher in ground wter (wells) 5 nd 1 m downslope of the inflow pipe thn soil wter smpled t m from the inflow pipe. umbers of totl nd fecl coliform bcteri in shllow ground wter declined by pproximtely 1 fold every 7 d for the first 14 d regrdless of vegettive tretment, seson of the yer, distnce downslope from the inflow pipe, or well depth. Totl nd fecl coliform numbers in shllow ground wter (1.5 nd 2. m wells) on the study plots immeditely prior to wstewter ppliction, which corresponded to 9 to 12 d since the wstewter ppliction, were usully less thn wht ws found in ground wter in 1.5 nd 2. m wells in grss nd forest riprin vegettion tht did not receive wste ppliction or were not grzed (control tretments) regrdless of vegettive tretment or seson of the yer. Fourteen dys fter wstewter ppliction, mortlity of totl coliform bcteri correlted with decresing soil moisture nd incresing ground wter temperture in 1.5 m wells (r 2 =.89) nd in 2. m wells (r 2 =.89) (Fig. nd 4). Fourteen dys fter wstewter ppliction, mortlity of fecl coliform bcteri lso correlted with decresing soil moisture nd incresing ground wter temperture in 1.5 m wells (r 2 =.82) nd 2. m wells (r 2 =.76). DISUSSI This reserch reveled tht: (i) totl nd fecl coliform numbers in the pulse of pplied wstewter did not decline s wter moved downslope regrdless of vegettion type or seson of the yer; (ii) totl nd fecl coliform numbers in soil wter nd ground wter t 2 nd m from the input source were slightly higher in 2 m grss1 m forest filterstrips thn the 1 m grss2 m midencne filterstrips nd 1 m grss2 m forest filterstrips in ll sesons smpled; (iii) totl nd fecl coliform numbers in ground wter declined by pproximtely 1fold every 7 d for the first 14 d regrdless of vegettive tretment or seson of the yer; (iv) totl nd fecl coliform numbers in soil wter nd in ground wter positively correlted with soil wter or ground wter temperture nd soil moisture; (v) totl nd fecl

8 TRY T AL.: IFLU F VGTATI I RIPARIA FILTRSTRIPS: I 121 Totl oliform Bcteri Fecl oliform Bcteri :1 6 6 D. 4 o m o 1 en Kg w ter / KG s in t6 o ler soil Kg wter. Fig. 4. Popultions of totl (left grph) nd fecl (right grph) coliform bcteri in ground wter in 2. m deep wells. Popultions of totl coliform bcteri in soil were explined by the following polynomil regression with ground wter temperture (WT) nd soil moisture (SM). Popultions of totl coliform bcteri = (WT).4826 (WT) 2.81 (WT) (SM) (SM) (SM), r 2 =.89 (p <.1). Popultions of fecl coliform bcteri = (WT).21 (wr) (WT).7672 (SM) +.4 (SM) (SM), r 2 =.76 (p <.1). coliform numbers in ground wter immeditely prior to ppliction, which corresponded to 9 to 12 d since the preceding wstewter ppliction, were usully less thn in ground wter in grss nd forest riprin vegettion tht did not receive wstewter ppliction or ws not grzed regrdless of vegettive tretment or seson of the yer; nd (vi) higher soil moisture nd wter temperture correlted in curviliner reltionship with higher numbers of totl coliform bcteri in soil wter nd shllow ground wter. Since filterstrips, regrdless of vegettion type or seson of yer, did not reduce concentrtions of totl or fecl coliform bcteri in surfce flow nd higher soil moisture nd wter temperture correlted with higher numbers of both totl nd fecl coliform bcteri in soil wter nd shllow ground wter, niml production opertions should not pply wstewter to lnd when surfce runoff or leching (nd thus, input of enteric bcteri) to wtercourse re likely to occur. Animl production opertions my need holding system (tnks nd/or ponds) tht cn store both liquid nd solid wste until they cn pply wste to lnds in stble period of wrm dry wether. Animl production opertions my need to locte in res where there re long periods of wrm dry wether so they cn pply wste to griculturl lnds with resonble ssurnce tht the input of high concentrtions enteric bcteri to surfce nd ground wter will not occur. Since totl nd fecl coliform numbers in ground wter declined by pproximtely 1fold every 7 d for the first 14 d, nd fter 9 to 12 d fecl nd totl coliform bcteri were t or below bckground concentrtions, the conclusion cn be drwn tht lnd ppliction of wstewter is vible option of disposl tht, if prcticed with discretion, does not necessrily led to contmintion of surfce or ground wter. Becuse filterstrips, regrdless of vegettion type, reduced totl nd fecl coliform popultions by two to three log orders of mgnitude compred with the source, niml confinement res should hve 2 to m vegetted filterstrip between the nimls nd wtercourses. The filterstrips should be growing vegettive species best suited to the climte nd soil type. The grss nd forest filterstrips tht hd no niml wste pplied to them hd totl coliform bcteril popultions rnging from 72 to 14 4 per 1 ml wter nd fecl coliform bcteri in soils rnged from 8 to 58 per 1 ml wter. Forest nd grss in riprin res provide hbitt for lrge vriety of wrm blooded wildlife tht will deposit enteric bcteri in soils nd wter. Severl studies hve found significnt popultions of enteric bcteri in soils nd wter in res not influenced by humn ctivity (Buckley et l., 1998; iemi nd iemi, 1991; Gry et l., 1985; Dorn nd Linn, 1979). Therefore, we cnnot expect soils or wter in res tht re not influenced by nthropogenic ctivities to be completely free of enteric bcteri. Bckground concentrtions of enteric bcteri in soils nd wter in res tht re not influenced by humn or griculturl opertions need to be estblished to determine if ppliction of humn or niml wste is polluting the environment. Animl producers need to be wre of the potentil for the spred of disesecusing microorgnisms to themselves nd others when hndling nd pplying solid nd or liquid wste. We isolted nd identified 14 different species of bcteri tht grew on totl or fecl coli

9 1214 J. VIR. QUAL.. VL. 29, JULYAUGUST 2 form medi tht cn cuse disese in humns. Most species of bcteri tht were isolted nd identified grow well in moistwrm hbitts, but during this study mny species were lso isolted in the drier utumn nd summer months. Diseses ssocited with enteric bcteri rnge from bcteri tht cuse mild to life thretening gstroenteritis, heptitis, skin infections, wound infections, conjunctivitis, respirtory infections, nd generlized infections (Moe, 1997). We lso need to be wre of the potentil for the spred of disesecusing microorgnisms to griculturl lnds nd to the length of time these orgnisms cn survive in soils even under dverse conditions for their survivl. The opportunity for trnsfer of these orgnisms from soils fter lnd ppliction of niml wste to surfce nd ground wter nd ultimtely humns will depend in prt on their bility to survive in the soil environment. AKWLDGMTS This work ws supported through the USDA Agriculturl Reserch Service, orthwest Irrigtion nd Soils Reserch Lbortory, Kimberly, Idho; USDA Agriculturl Reserch Service, Southest Wtershed Reserch Lbortory, Tifton, Georgi; nd the USDA Foreign Agriculturl Service/Interntionl oopertion nd Development under oopertive Agreement no Any opinions, findings, nd conclusions or recommendtions expressed in this publiction re those of the uthors nd do not necessrily reflect the views of the United Sttes Deprtment of Agriculture. The uthors wish to thnk Bobby Shiver, Gry Knight, Dee Ann Webb, nd Sheryl Ver Wey for technicl ssistnce. RFRS AbuAshour, J., D.M. Joy. H. Lee, H.R. Whiteley, nd S. Zelin Movement of bcteri in unsturted soil columns with mcropores. Trns. ASA 41:1415. Buckhouse, J.., nd G.F. Gifford Wter qulity implictions of cttle grzing on semirid wtershed in southestern Uth. J. Rnge Mnge. 29:1911. Buckley, R.,. lough, W. Wrnken, nd. Wild oliform bcteri in strembed sediments in subtropicl rinforest conservtion reserve. Wter Res. 2: oyne, M.S., R.A. Gilifillen, R.W. Rhodes, nd R.L. Blevins Soil nd fecl coliform trpping by grss filter strips during simulted rin. J. Soil Wter onserv. 5:4548. Drling, L.A., nd G.B. olthrp ffects of livestock on wter qulity of mountin strems. p. 18. In Proc. Symp. WterAniml Reltions. ollege of Southern Idho, Twin Flls, ID. June 197. WterAniml Reltions ommission, USDAARS, Kimberly, ID. Donnison. A.M., nd R. ooper Fecl coliform decline on psture irrigted with primry treted metprocessing effluent. ew Zelnd J. Agric. Res. 2: Dorn, J.W., nd D.M. Linn Bcteriologicl qulity of runoff wter from psturelnd. Appl. nviron. Microbiol. 7: ntry, J.A., R.K. Hubbrd, J.. Thies, nd J.J. Furhmnn. 2. The influence of vegettion in riprin filterstrips on coliform bcteri: II. Survivl in soil. J. nviron. Qul. 29: (this issue). Frser, R.H., P.K. Brten. nd D.A. Pinney Predicting strem pthogen loding from livestock using geogrphicl informtion systembsed delivery model. J. nviron. Qul. 27: Gry, H.L., S.R. Johnson, nd S.L. Ponce ttle grzing impct on surfce wter qulity in olordo front rnge strem. J. Soil Wter onserv. 4: Greenberg, A.F., L.S. lescerl, nd A.D. ton Stndrd methods for the exmintion of wter nd wstewter. 18th edition. Americn Public Helth Assocition, Wshington, D. Howell, J.M., M.S. oyne, nd P.L. ornelius ffect of prticle size nd temperture on fecl bcteri mortlity rtes nd the fecl coliform/fecl streptococci rtio. J. nviron. Qul. 25: Hubbrd, R.K., G.L. ewton, J.G. Dvis, R. Lowrnce, G. Vellidis, nd.r. Dove itrogen ssimiltion by riprin buffer systems receiving swine lgoon wstewter. Trns. ASA 41: Hubbrd, R.K., nd J.M. Sheridn Wter nd nitrtenitrogen losses from smll, uplnd ostl Plin Wtershed. J. nviron. Qul. 12: Huysmn, F., nd W. Verstrete Wter fcilitted trnsport of bcteri in unsturted soil columns: Influence of cell surfce hydrophobicity nd soil properties. Soil Biol. Biochem. 25:89. Jordn, T.., D.T. orrell, nd D.. Weller utrient interception by riprin forest receiving inputs from djcent croplnd. J. nviron. Qul. 14: Kirk, R xperimentl design: Procedures for the behviorl sciences. 2nd ed. Brooks ole Publishing o., Belmont, A. Kunkle, S.H Sources nd trnsport of bcteril indictors in rurl strems. p In Interdisciplinry spects of wtershed mngement. AS, Bozemn, MT. Lowrnce, R., R. Todd, J. Fil, Jr.,. Hendrickson, Jr., R. Leonrd, nd L. Asmussen Riprin forests s nutrient filters in griculturl wtersheds. BioScience 4:7477. Lowrnce, R., G.Vellidis, R.D. Wuchope, P. Gy, nd D.D. Bosch Herbicide trnsport in mnged riprin forest buffer system. Trns. ASA 4: Moe,.L Wterborne trnsmission of infectious gents. p In.J. Hurst et l. (ed.) Mnul of environmentl microbiology. Americn Society of Microbiology Press, Wshington, D. iemi, R.M., nd J.S. iemi Bcteril pollution of wters in pristine nd griculturl lnds. J. nviron. Qul. 2: Peterjohn, W.T., nd D.L. orrell utrient dynmics in n griculturl wtershed: bservtions of the role of riprin forest. cology 65: SAS Institute SAS user's guide: Sttistics. Version 6.. SAS Institute, ry,. Snedecor, W.G., nd W.G. ochrn Sttisticl methods. 7th ed. Iow Stte Univ. Press, Ames. Snyder,.J., S. Mostghimi, D.F. Berry, R.B. Reneu, S. Hong, P.W. Mclelln, nd.p. Smith Impct of riprin buffers on griculturl nonpoint source pollution. J. Am. Wter Res. Assoc. 4:8595. Sorber,.A., nd B.. Moore Survivl nd trnsport of pthogens in sludgemended soil: A criticl literture review. PA 6 S Wter ngineering Reserch Lbortory, incinnti. H. USPA tionl primry drinking wter stndrds. PA 81 F941A. ffice of Wter, USPA, Wshington, D. USPA nvironmentl impcts of niml feeding opertions. Preliminry dt summry. Feedlots point source ctegory study. USPA, ffice of Wter, Stndrds nd Applied Sciences Division, Wshington D. Wlker, S.., S. Mostghimi, T.A. Dillh, nd F.. Woeste Modeling niml wste mngement prctices: Impcts on bcteri levels in runoff from griculturl lnd. Trns. ASA : Young, R.A., T. Hundtrods, nd W. Anderson ffectiveness of vegetted buffer strips in controlling pollution from feedlot runoff. J. nviron. Qul. 9:48487.