Moisture Quotients for Ammonia Volatilization from Four Soils in Potato Production Regions

Transcription

1 Wter Air Soil Pollut (27) 183: DOI 1.17/s Moisture Quotients for Ammoni Voltiliztion from Four Soils in Potto Production Regions G. D. Liu & Y. C. Li & A. K. Alv Received: 18 Septemer 26 / Accepted: 4 Ferury 27 / Pulished online: 1 Mrch 27 # Springer Science + Business Medi B.V. 27 Astrct Ammoni (NH 3 ) emission from nitrogen (N) fertilizers used in griculture decreses N uptke y the crop nd negtively impcts ir qulity. In order to etter understnd the fctors influencing NH 3 emission from griculture, this reserch ws conducted with four mjor soils used for potto production: Biscyne Mrl Soil (BMS, ph 7.27), nd Krome Grvelly Lom (KGL, ph 7.69) from Florid; nd Quincy Fine Snd (QFS, ph 6.65), nd Wrden Silt Lom (WSL, ph 6.46) from Wshington. Potssium nitrte (KNO 3 ), mmonium nitrte (NH 4 NO 3 ), mmonium sulfte ((NH 4 ) 2 SO 4 )orure((nh) 2 CO) sources were evluted for mmoni voltiliztion t 75 kg N h 1 rte. The soil wter regime ws mintined t either 2 or 8% of field cpcity (FC), nd incuted t 11, 2 or 29 C. Results indicted tht NH 3 voltiliztion rte t 2% FC ws 2 to 3-fold greter thn tht t 8% FC. The cumultive voltiliztion loss over 28 dys rnged from.21% of N pplied s NH 4 NO 3 to 25.7% s (NH 4 ) 2 SO 4. Results of this study demonstrte tht NH 3 voltiliztion ws ccelerted t the low soil wter regime. Moisture quotient (Q) is defined s rtio of NH 3 emission rte t 2% FC to tht t 8% FC oth t the sme temperture. The pek Q vlues of NH 3 voltiliztion were up to 2.8 for the BMS soil t 2 C, for the KGL soil t 29 C, 19. for the QFS soil t 2 C, nd 74.1 for the WSL soil t 29 C, respectively. Thus, mintining suitle soil wter regime is importnt to minimize N-loss vi NH 3 voltiliztion nd to improve N uptke efficiency nd ir qulity. Keywords Ammoni emission. Soils from Florid nd Wshington. Fertilizers. Soil wter regimes. Nitrogen mngement for pottoes 1 Introduction G. D. Liu : Y. C. Li (*) Deprtment of Soil nd Wter Sciences, Tropicl Reserch nd Eduction Center, University of Florid, 1895 SW 28th St., Homested, FL 3331, USA e-mil: yunli@ufl.edu A. K. Alv Vegetle nd Forge Crops Reserch Lortory, USDA-ARS, 2416 N. Bunn Rd., Prosser, WA 9935, USA Ammoni (NH 3 ) emission from griculture including livestock wstes hs een recognized since the erly nineteenth century (Boussingult 1851; Bussink nd Oenem 1998; Sprengel 1839). Ammoni voltiliztion from N fertilizers used for griculturl production reduces utiliztion efficiency of pplied nitrogen (N) fertilizers. The direct nnul world-wide economic loss due to NH 3 voltiliztion from chemicl N fertilizers pplied to frmlnds is US$11.6 illion

2 116 Wter Air Soil Pollut (27) 183: (FAO 21). Ammoni voltiliztion lso cuses serious climtic nd environmentl prolems (Gy nd Knowlton 25; NRC 23). Ammoni emission occurs from livestock mnure s well. However, contriution from this source is rther insignificnt s compred to the glol mmoni emission from chemicl N fertilizers. Therefore, reserch interests on mmoni emission from niml mnures were rther sudued in the erly 195s. (Bussink nd Oenem 1998). However, interest in this re of reserch incresed with the reliztion of negtive environmentl impct of gseous N emission on ir qulity nd their contriution to greenhouse gses (Anej et l. 26; Buijsmn et l. 1987; Fngmeier et l. 1994; Gy nd Knowlton 25; Kirchmnn et l. 1998; Vn Breemn et l. 1982). Ammoni emission from griculturl sources contriutes to significnt portion of totl NH 3 emission (Ferm 1998; Schlesinger nd Hrtley 1992). In the Western Europe 92% of ll NH 3 emission ws trced to griculturl origins (Kirchmnn et l. 1998). Consequently, reduction in NH 3 emission from griculturl production prctices should increse the utiliztion efficiency of pplied N fertilizers nd improve ir qulity (Anej et l. 26; Buijsmn et l. 1987; Fngmeier et l. 1994; Gy nd Knowlton 25; Kirchmnn et l. 1998; Vn Breemn et l. 1982). Voltilized NH 3 is the only nturl lkline gs in the erth s tmosphere (Asmn et l. 1982; Schlesinger nd Hrtley 1992). NH 3 hs reltively short residence time in the tmosphere, out 1 dys, due to its rpid conversion to nitrous oxide (N 2 O) (Dentener nd Crutzen 1994) nd to mmonium (NH + 4 ), nd the deposition of NH 3 onto soil nd wter surfces (Anej et l. 1998; Fowler et l. 1997). There is n nnul flux of out MT (metric tones) of N derived from the glol sources of NH 3 emitted into the tmosphere (Schlesinger nd Hrtley 1992). Indeed, NH 3 is the third most undnt N gs (fter N 2 nd N 2 O) in the tmosphere. The emitted NH 3 cn prtilly e deposited in situ (within c 5 km from the source) or ex situ (c 4 km from the source) y either dry deposition or wet deposition (Duce et l. 1991; Ferm1998; Schlesinger nd Hrtley 1992; Wrneck 1999). Schlesinger nd Hrtley (1992) estimted tht 76% of emitted NH 3 ( MT N/yr) ws deposited onto wter or soil surfces. This deposited NH 3 cuses environmentl prolems such s soil nd wter ody cidifiction, eutrophiction nd forest dieck (Fngmeier et l. 1994; Vn Breemen et l. 1982). Perl (1991, 1995) reported signs of enhnced eutrophiction in severl esturine nd costl ecosystems impcted y tmospheric N deposition. In ddition to soil nd wter ody pollution, the emitted NH 3 excertes glol climte chnge. Dentener nd Crutzen (1994) estimted tht 4% (3 1 6 MT N/yr) of the glolly emitted NH 3 cn e oxidized y OH rdicls nd NO 2 (Finlyson-Pitts nd Pitts 2), minly in the tropics. A frction of the oxidized NH 3 is trnsformed to N 2 O nd this cn constitute 5% of the glol N 2 O emission (Ferm 1998). N 2 O is potent greenhouse gs nd pproximtely 31-fold more powerful thn CO 2 in trpping het in the tmosphere (Finlyson-Pitts nd Pitts 2; IPCC 1996). The reminder of the emitted NH 3 rects with cid gses such s SO 2 generted from fossil fuel comustion; nd these rections provide mjor portion of the mient fine prticulte mtter tht is clled PM2.5 (the frction of erosol prticles with n erodynmic dimeter less thn 2.5 μ) (Finlyson- Pitts nd Pitts 1986). PM2.5 prticles re hrmful to humn helth (Dockery et l. 1993; Kelsll et l. 1997; Mrczzn et l. 21; Pgno et l. 1998; Schwrtz et l. 1996) ecuse they cn e inhled nd cn penetrte into the gs-exchnge region of the lung (Brunekreef nd Holgte 22). Therefore, PM2.5 prticles cuse numerous helth prolems including sthm, ronchitis, nd cute nd chronic respirtory symptoms such s shortness of reth nd pinful rething, nd premture deths. Although NH 3 loss from griculture hs een recognized for lmost two centuries (Bussink nd Oenem 1998), the control of NH 3 emission from nthropogenic ctivities is still uncertin. Fenn nd Hossner (1985) reported tht the vriility in soil wter content is proly the mjor fctor ffecting NH 3 loss from surfce pplied N fertilizers. However, there re mny conflicting reports on the effects of soil moisture on NH 3 voltiliztion. Fox nd Hoffmn (1981) reported tht less thn 1% NH 3 loss occurred if 1 mm rinfll fell within 3 dys fter ppliction of ure ut the NH 3 loss ws greter thn 3% if there ws no rinfll within 6 dys fter ppliction. Their results showed tht high soil moisture reduced NH 3 loss vi voltiliztion. However, Sommer et l. (24) found tht high moisture content of the surfce lyer

3 Wter Air Soil Pollut (27) 183: of soil ws one of the most importnt environmentl fctors cusing high rtes of NH 3 voltiliztion from pplied N-fertilizers. Previously, Fenn nd Hossner hd discovered tht soil surfce with low moisture content reduced NH 3 loss from surfce pplied ure nd inorgnic N fertilizers in the field. Vlek nd Crter (1983) showed tht ure hydrolysis t the permnent wilting point (PWP) ws reltively high ut decresed rpidly with further soil drying ecuse soil urese requires dequte surfce wter to fcilitte sustntil rtes of ure hydrolysis (Fox nd Hoffmn 1981). Soil urese my not e le to mintin its ctivity to hydrolyze ure ecuse ville wter is limited, s when the wter potentil is lower thn tht t the PWP. These conflicting results cn e ttriuted minly to different experimentl conditions or reserch methods. They my lso result from the filure to model the effects of moisture on NH 3 emission ecuse the effects of moisture differ with time, soil type, fertilizer species, temperture, nd the like. Currently, the sic fctor, tht indictes the effects of soil moisture on NH 3 voltiliztion, is the percentge chnge etween soil wter regimes (Fox nd Hoffmn 1981). Percentge is useful indictor when smll numer of different soil moisture levels re nlyzed ut not when lrge ody of dt must e done. Actully, the current references focus on single comprison etween vrious soil-moistures (Fenn nd Miymoto 1981; Fox nd Hoffmn 1981) ecuse it is not convenient to monitor the dynmic effects of chnging moisture levels on NH 3 emission in period of time without the enefit of scientific concept or model. We propose tht the moisture quotient is potentilly useful concept to descrie the effects of soil moisture levels on NH 3 emission. The concept of moisture quotient ws introduced y Emerger (1955). This concept nd the mpping of ioclimtic zones resulted in the zoning of vegettion. Indeed, the moisture quotient continues to e of fundmentl vlue to geogrphers nd climtologists. Additionlly, the concept is used in studies to elucidte the mechnisms of control of dmge y wood-oring insects, rot fungi, nd stin fungi to timers in uildings (Oliver 1997; Viitnen 1997; Voutilinen 25). However, no literture reports could e found on the use of the moisture quotient to elucidte the effects of moisture levels on NH 3 emission rtes from different soils suject to vrying conditions. The moisture quotient is defined s the rtio of the NH 3 voltiliztion rte t one moisture level to tht t higher moisture level (2 nd 8% FC, respectively in this study); oth under identicl temperture nd other environmentl conditions. The moisture quotient my e used to ssess the dynmic effects of soil moisture level on NH 3 voltiliztion. The ojectives of this reserch were to: (1) present new concept of the moisture quotient to descrie the effects of soil wter content on NH 3 voltiliztion losses from different N sources; (2) model the effects of soil moisture on NH 3 voltiliztion using the concept of the moisture quotient; nd (3) quntify the moisture quotients of NH 3 voltiliztion from different N sources pplied to vriety of soils t severl tempertures. 2 Mterils nd Methods 2.1 Soils The typicl soils used for potto production in South Florid re Biscyne Mrl soil (BMS, lomy, crontic, hyperthermic, shllow Typic Fluvquents) nd Krome Grvelly Lom (KGL, lomyskeletl cronic, hyperthermic Lithic Udorthents). The min rottion on oth of the BMS nd KGL soils is potto sweet corn. Fertilizer ppliction rtes re 22 kg N h 1 for potto production nd 22 kg Nh 1 for sweet corn under center pivot irrigtion system. Quincy Fine Snd (QFS, Mixed, mesic Xeric Torripsmments) nd Wrden Silt Lom (WSL, Corse-silty, mixed, mesic, Xerollic Cmorthids, drk gryish-rown soil) occur in the Columi Bsin potto production region in south centrl Wshington (Liu et l. 27). The typicl rottion on oth soils hs een corn whet potto under center pivot irrigtion system. Fertilizer history for potto hs een: 112 kg h 1 N s ure rodcst pre-plnting ppliction, nd 224 kg N h 1 s in-seson fertigtions (using ure mmonium nitrte solution, through pivot) in five eqully split pplictions t 2 weeks intervl strting 3 weeks fter seedling emergence. For corn nd whet: 224 kg N h 1 s ure is pplied during cultivtion. No in-seson N ppliction is followed. All four soils hve een used extensively for crop production ut hve different cidities. The

4 118 Wter Air Soil Pollut (27) 183: Tle 1 Chrcteristics of the soils tested from Florid nd Wshington Soil Source loction ph EC e (μs/cm) SHC f cm/hr Totl P (mg/kg) Totl N OM g (%) Prticle size (%) (%) Cly Silt Snd BMS Florid , KGL Florid , QFS c Wshington n h 1, WSL d Wshington n 3, Biscyne Mrl Soil, Krome Grvelly Lom, c Quincy Fine Snd, d Wrden Silt Lom. e Electricl conductivity. f Sturted hydrulic conductivity, source: Muñoz-Crpen et l. 25. g Orgnic mtter. h not ville. two from Florid re sic soils with ph 7.27 for the BMS soil nd 7.69 for the KGL soil. The two from Wshington re cidic soils with ph 6.65 for the QFS soil nd the 6.45 for the WSL soil. Some of the properties nd fertilizer history of these soils re presented in Tles 1 nd Incution Temperture The incution tempertures chosen for use in this study were sed on the men temperture in the selected production regions during the growing seson. In the Columi Bsin production region of Wshington, the mximum, verge nd minimum tempertures for the potto growing seson re 29, 2 nd 11 C, respectively, sed on the dily climtic dt for 2 through 23. In Florid, the growing seson for potto is from Octoer to My. The corresponding mximum, verge nd minimum tempertures re 26.5, 22.5 nd 18.4 C. These tempertures re within the rnge of those in Wshington; hence, 29, 2 nd 11 C were used s the incution tempertures for this investigtion. 2.3 Soil Moisture Content During Incution Soil wter contents t field cpcities of the BMS, KGL, QFS, nd WSL soils were mesured for ll four soils using the clssic trnsient dringe method: A 25 ml plstic cup with 12 1-mm-dimeter holes distriuted evenly t the ottom ws filled with out 2 g of ech of the four soils in three replictes (4 soils 3 replictes= 12 cups). The soil in the cup ws flooded over night nd llowed to drin until the dringe stopped completely. Grvittionl soil wter content ws determined which represents the field cpcity wter content for ech soil. The incution of the treted soils ws done t 2 nd 8% FC soil wter contents for the respective soils. After the ottles were set up, ech ottle ws plced inside seled plstic Ziploc storge g (23 3 cm) to void ny moisture loss. 2.4 Ammoni Trpping nd Chemicl Anlysis Three hundred grms (dry weight) of ech soil ws plced in 5-ml incution ottle (Liu et l. 27). The soil-surfce re in the ottle ws out 6 cm 2. Tle 2 The cropping systems nd N fertiliztion (kg h 1 ) in the soils in the study Soil site rottion BMS Florid potto sweet corn KGL Florid potto sweet corn QFS Wshington corn whet potto WSL Wshington corn whet potto Fertiliztion N Corn Pre-plnting In-seson Whet Pre-plnting In-seson Potto Pre-plnting In-seson

5 Wter Air Soil Pollut (27) 183: N-loss (kg N h -1 ) BMS KGL QFS WSL c c c cd d c d c d 2% 8% 2% 8% 2% 8% 11 C 2 C 29 C c Fig. 1 Cumultive N-loss over 28 d vi mmoni emission from four soils mended with (NH 4 ) 2 SO 4 t either 2 or 8% field cpcity (FC) nd 11, 2 or 29 C incution tempertures. BMS: Biscyne Mrl Soil; KGL: Krome Grvelly Lom; QFS: Quincy Fine Snd; WSL: Wrden Silt Lom. Verticl rs not followed y the sme letter re significntly different t P 5 y DMRT t the sme temperture nd soil wter regime N-loss (kg N h -1 ) c d BMS KGL QFS WSL c d c d c c d 2% 8% 2% 8% 2% 8% 11 C 2 C 29 C c d Fig. 3 Cumultive N-loss over 28 d vi mmoni emission from four soils mended with NH 4 NO 3 t either 2 or 8% FC nd 11, 2 or 29 C incution tempertures. BMS: Biscyne Mrl Soil; KGL: Krome Grvelly Lom; QFS: Quincy Fine Snd; WSL: Wrden Silt Lom. Verticl rs not followed y the sme letter re significntly different t P 5 y DMRT t the sme temperture nd soil wter regime The soil wter content ws djusted to either 2 or 8% FC. The wter content t FC for the four soils evluted in this study ws (v/m sed on oven dry soils): 64.5±11.2, 323.4±6.7, 247.4±2.7, nd ±2.8 ml kg 1 for the BMS, KGL, QFS, nd WSL soils, respectively. One ml of 45 mg N ml 1 solution [s one of the following: either mmonium sulfte- (NH 4 ) 2 SO 4, or ure-(nh 2 ) 2 CO, mmonium nitrte- NH 4 NO 3, or potssium nitrte -KNO 3 ] ws uniformly pplied on the soil surfce with micropipette. The mount of N pplied ws 45 mg N per ottle, equivlent to 75 kg N h 1 sed on surfce re of the soil in the ottle. A tretment with only deionized wter ws included s control. Thus, there were 4 soils 5 N sources (including the control) 3 tempertures 2 soil wter regimes 3 replictions N-loss (kg N h -1 ) c c BMS KGL QFS WSL c c c c c 2% 8% 2% 8% 2% 8% 11 C 2 C 29 C d c Fig. 2 Cumultive N-loss over 28 d vi mmoni emission from four soils mended with ure t either 2 or 8% FC nd 11, 2 or 29 C incution tempertures. BMS: Biscyne Mrl Soil; KGL: Krome Grvelly Lom; QFS: Quincy Fine Snd; WSL: Wrden Silt Lom. Verticl rs not followed y the sme letter re significntly different t P 5 y DMRT t the sme temperture nd soil wter regime which required 36 totl incution ottles. Ech incution ottle ws plced in seled plstic Ziploc storge g (23 3 cm) nd plced in n incutor t 11, 2 or 29 C, s pproprite. A sponge spiked with the trpping solution ws inserted into the mouth of the ottle to trp the voltilized NH 3. Ech sponge (out 5 cm in dimeter) ws cut from Yellow Flower Sponge mteril (Arrow Plstic Mnufcturing Compny, Elk Grove Villge, IL). Ech cut sponge ws spiked with.8 ml of trpping solution consisting of 35 ml of concentrted phosphoric cid, 25 ml of glycerol nd 715 ml deionized wter (He et l. 1999). The sponge with the trpping solution ws smpled t 1, 3, 7, 14, nd 28 dys nd new sponge (with the trpping solution) ws inserted into the mouth of the ottle to trp NH 3 for ech susequent incution period. The mmoni in sponges ws extrcted with 25 ml of 1 M KCl nd mesured using n Auto Anlyzer III (Brn+Luee GmH, Werkstrsse, Norderstedt, Germny, ccording to EPA Method 35.1 (EPA 1993). 2.5 Moisture Quotient (Q) nd Active Moisture Quotient (AQ) of Ammoni Voltiliztions The moisture quotient (Q) ofnh 3 voltiliztion is the rtio of NH 3 voltiliztion rtes t two different soil moisture levels oth under the sme temperture nd soil conditions. Q is defined in this reserch s follows: Q ¼ R 2 FC 2 FC 1 R 1 :6 ð1þ

6 12 Wter Air Soil Pollut (27) 183: Tle 3 Soil wter content (ml 1 1 g) of the four soils used in this study over rnge of field cpcity (FC) regimes 1% FC TW BW 8%FC TW AW c 2%FC TW AW BMS d 6.5±1.1 h 1.6± KGL e 32.3±.7 3.± QFS f 24.7±.3.8± WSL g 32.6±.3 1.7± Totl wter volume. Bound wter volume which is the difference etween wind-dried nd oven-dried (15 C for 6 h) soil, c Aville wter volume, d Biscyne Mrl Soil, e Krome Grvelly Lom, f Quincy Fine Snd, g Wrden Silt Lom, h The vlues re Men ± STD. where Q is the moisture quotient of the rtes of NH 3 voltiliztion. R 1 nd R 2 re the rtes of NH 3 voltiliztion t either 8% (FC 1 )or2%(fc 2 ) under the sme temperture. Therefore, FC 1 -FC 2 =6%, nd (FC 1 -FC 2 )/.6=1%. Q is sclr quntittive mesure of the chnge in NH 3 voltiliztion rte; ut Q is sclr quntity, which does not indicte the direction (increse or decrese) of the chnge in the NH 3 voltiliztion rte etween different soil moisture levels. In order to descrie oth quntittive nd qulittive chnges of NH 3 voltiliztion rte, ctive moisture quotient (AQ) is used nd defined s follows. AQ ¼ R 2 R 1 FC 2 FC 1 R 1 :6 ð2þ where AQ is the ctive moisture quotient of the rtes of NH 3 voltiliztion, nd the other symols re the sme s those in Eq Sttisticl Anlysis The Sttisticl Anlysis System (SAS) pckge version 9.1, (23, SAS Institute, Inc., Cry, NC), ws used to perform the sttisticl nlyses. The dt were tested y Duncn s Multiple Rnge Test (DMRT) with sttisticl significnce of P 5. 3 Results nd Discussions 3.1 Differences in Cumultive N-loss Between Two Soil Wter Regimes There were significnt differences in cumultive NH 3 emission etween 2 nd 8% FC over the 28 d incution period cross ll N sources nd ll incution tempertures (Figs. 1, 2 nd 3). Cumultive N-losses cross the four soils t 2% FC were Tle 4 Summry of ANOVA test for fctors influencing NH 3 emission Source DF Anov SS Men squre F vlue Pr > F Moisture E E <.1 Fertilizer 4 6.9E E <.1 Soil E E <.1 Time E E <.1 Temperture 2 5.1E E <.1 Replicte E E Fertilizer Moisture E+9 4.7E <.1 Soil Fertilizer E E <.1 Soil Moisture E E <.1 Time Moisture E+8 1.2E <.1 Time Fertilizer E+9 1.3E <.1 Soil Temperture E E <.1 Time Soil E+8 2.6E <.1 Fertilizer Temperture 8 5.7E E Temperture Moisture E+7 7.9E Time Temperture E E

7 Wter Air Soil Pollut (27) 183: N-loss (kg N h -1 ) BMS KGL QFS WSL % 8% 2% 8% 2% 8% 11 C 2 C 29 C Fig. 4 Cumultive N-loss over 28 d vi mmoni emission from four soils mended with KNO 3 t either 2 or 8% FC nd 11, 2 or 29 C incution tempertures. BMS: Biscyne Mrl Soil; KGL: Krome Grvelly Lom; QFS: Quincy Fine Snd; WSL: Wrden Silt Lom. The columns re not ppering ecuse the cumultive N-losses were too smll. To show the mount of the N-losses, the vlues re presented on the figure 3.3-, 4.1- nd 3.5-fold greter thn those t 8% FC for (NH 4 ) 2 SO 4, ure, NH 4 NO 3, respectively. Ammoni voltiliztion loss ws 19.3 kg N h 1 for the KGL soil mended with (NH 4 ) 2 SO 4 incuted t 2 C nd 2% FC. The lest N loss from the pplied fertilizers with instnt or convertile NH 4 -N source ws.2 kg N h 1 for the WSL soil mended with NH 4 NO 3 incuted t 2 C nd 8% FC. Soil wter cn e simply ctegorized s free (ville) wter, nd ound (unville) wter. Wter cn e ound to the soil mtrix y dhesive forces, cohesive forces nd osmotic forces (Hilhorst et l. 21; Koorevr et l. 1983). Unlike unound wter, ound wter loses its energy nd is le to exert little influence on the soil processes ecuse its wter molecules re sored to the surfce of prticles nd the dipoles re immoilized (Jckson nd Schmugge 1989; Njoku nd Entekhi 1996). For exmple, ound wter doesn t ct s solvent, which is needed to trnsport mmonium NH4 þ in the soil. Among the four soils, KGL contined the lest mount of free wter t 2% FC (Tle 3). Additionlly, sturted hydrulic conductivity of the KGL soil ws 34-fold greter thn tht of the BMS soil (Tle 1, Muñoz-Crpen et l. 25). This shows tht the wter-holding ility of the KGL soil ws very poor. The results for the four soils showed tht the lower the soil moisture content, the higher ws the mount of NH 3 voltiliztion (Figs. 1, 2 nd 3 nd Tle 3). Therefore, N fertilizer mngement nd wter mngement should e integrted to minimize NH 3 emission. Furthermore, doption of crop genotypes tht re wter efficient nd thorough weed control my mitigte soil wter stress nd decrese NH 3 emission to the tmosphere. Ammoni emissions from the BMS nd KGL soils were greter thn tht from the QFS nd WSL soils. This could e, in prt, due to the greter ph of the former s compred to tht of the ltter soils (Tle 1). The ph for the KGL soil ws the highest mong the four soils evluted in this study, which recorded the highest NH 3 emission rte mong the four soils (Liu et l. 27). In limited wter-supply situtions, it is criticl to mintin dequte soil wter content during the period immeditely following the ppliction of N fertilizers. Likewise, N fertilizer ppliction should e scheduled when the soil contins dequte soil wter content. The N-losses from the four soils in the N-loss (kg N h -1 ) BMS KGL QFS WSL % 8% 2% 8% 2% 8% Fig. 5 Cumultive N-loss over 28 d vi mmoni emission from four soils mended with nothing (control) t either 2 or 8% FC nd 11, 2 or 29 C incution tempertures. BMS: Biscyne Mrl Soil; KGL: Krome Grvelly Lom; QFS: Quincy 11 C 2 C 29 C Fine Snd; WSL: Wrden Silt Lom. The columns re not ppering ecuse the cumultive N-losses were too smll. To show the mount of the N-losses, the vlues re presented on the figure

8 122 Wter Air Soil Pollut (27) 183: control, or KNO 3 mended tretments were negligile. Thus, the following discussion minly focuses on the NH 3 emission from either (NH 4 ) 2 SO 4, ure, NH 4 NO 3. ANOVA test shows there were significnt interctions etween N source moisture, soil N source, soil moisture, time moisture, time N source, soil temperture, time soil, N source temperture, nd temperture moisture (Tle 4). Prticulrly, the interctions etween moisture nd ech of the other fctors were lwys highly significnt. This further indictes tht the importnce of dequte soil wter mngement following N fertiliztion to minimize gseous N losses. However, there ws little difference when the soils without fertilizer (control) or with fertilizers without ny instnt or convertile mmoni such s potssium nitrte (Figs. 4 nd 5). 3.2 Differences in Moisture Quotients of NH 3 Emission Rtes The moisture quotients (Q) ofnh 3 voltiliztion rtes were ssocited closely with temperture nd soil type (Figs. 6, 7 nd 8). The Q vlues were dynmic, chnging with time ecuse the ville NH 3 level decresed with time. At 29 C, Q incresed to mximum of for the KGL soil mended with (NH 4 ) 2 SO 4 (Fig. 6). However t 2 C, Q incresed to mximum of only 48.3 for the KGL soil mended with ure (Fig. 7). At 11 C, Q incresed to mximum of 19.3 for the WSL soil mended with NH 3 NO 3 (Fig. 8). All the Q vlues for the four soils showed significnt differences in the NH 3 emission rtes under two soil wter regimes. This indicted the NH 3 emission rtes under 2% FC significntly higher thn those under 8% FC. In the dry soil, the trnsport of NH4 þ ions from the soil surfce down to deep soil horizon ws restricted, hence led to incresed losses s NH 3 emission. At 29 C, the Q vlues for the soils showed single pek response curve with the pek on dy 14 with the exception of the BMS soil in which NH 3 emission peked on Dy 3 for oth (NH 4 ) 2 SO 4 nd ure ut R Fig. 6 The moisture quotient (Q) t 29 C for the rtes of mmoni voltiliztion from the four soils fertilized with five different N-sources under 2 nd 8% FC. BMS: Biscyne Mrl Soil; KGL: Krome Grvelly Lom; QFS: Quincy Fine Snd; nd WSL: Wrden Silt Lom

9 Wter Air Soil Pollut (27) 183: didn t pek for the other tretments (Fig. 6). The decelertion in NH 3 emission could e due to depletion of NH4 þ sources. At 29 C, the Q vlues for the KGL soil were the lrgest or the second lrgest mong the four soils were using either (NH 4 ) 2 SO 4 or ure. In fct, the mximum Q vlues for the KGL soil mended with ure were 5.7 to 6.1-fold greter thn those for the BMS, QFS nd WSL soils t 29 C. This indicted tht the NH 3 emission for the KGL soil ws most sensitive to soil wter regimes. At 29 C, NH 3 emission from QFS soil ws the lest responsive to chnges in soil wter content. With BMS soil t 29 C, the Q vlues vs. time showed rther modest erly pek only for (NH 4 ) 2 SO 4 nd ure sources (Fig. 6). At 2 C, however, the single pek response of the Q vs. time ws evident only in the BMS soil cross ll the three N sources with instnt or convertile mmonium; while for ll other soils, the Q vlues incresed continuously for the entire durtion of this study (Fig. 7). Vzquez-Rodriguez nd Rols (1997) reported tht nitrifiction incresed 2.8-fold with every 1 C increment in temperture. The ove results my e ttriuted to lower rte of nitrifiction t 2 C thn tht t 29 C, ecuse NH 3 emission cn lst longer if the NH4 þ source is sufficient nd low rte of nitrifiction would convert only smll mount of NH4 þ source into NO 3. At 2 C, the effect of lower soil wter content on NH 3 emission lsted longer thn tht t 29 C. Thus the influence of soil wter stress on NH 3 emission ws weker t 2 C thn t 29 C. Moreover t 11 C, the effects of soil wter stress on NH 3 emission from the four soils mended with ech of the three N sources were much less evident thn those t either 2 or 29 C (Figs. 6, 7 nd 8). Among the four soils tested the WSL soil showed the most positive response ut the BMS soil showed negtive response 3 dys following the incution. The QFS soil hd only smll chnges in the moisture quotient for the vrious fertilizers. The mximum Q vlues were 19.3, 48.3 nd cross soils t 11, 2 nd 29 C, respectively (Figs. 6, 7 nd 8). This suggests n increse in NH 3 emission with incresing wter stress. The mgnitude of this response Fig. 7 The moisture quotient (Q) t 2 C for the rtes of mmoni voltiliztion from the four soils fertilized with five different N-sources under 2 nd 8% FC. BMS: Biscyne Mrl Soil; KGL: Krome Grvelly Lom; QFS: Quincy Fine Snd; nd WSL: Wrden Silt Lom Moisture quotient (NH 4 ) 2 SO 4 (NH 2 ) 2 CO NH 4 NO 3 KNO 3 Control BM S QFS KGL WSL Time (d)

10 124 Wter Air Soil Pollut (27) 183: (NH 4 ) 2 SO 4 (NH 2 ) 2 CO BM S QFS KGL WSL ws however vrile in different soils. In this experiment, the soil wter content ws set t 2 nd 8% of FC for the respective soils. However, the grvimetric soil wter content t given soil wter regime tretment differed sustntilly cross these four soils. The soil wter contents t 8% FC tretment were: 48.3, 33.4, 26. nd 19.8 for the BMS, KGL, WSL nd QFS soils, respectively. The corresponding totl soil wter contents t 2% FC tretment were 12., 8.4, 6.7 nd 4.8% (Tle 3). There ws not much Q difference in ll of the four tested soils mended with KNO 3 nd the control ecuse there ws not ville mmonium or mmoni source to e emitted (Figs. 6, 7 nd 8) Differences in Active Moisture Quotients of NH 3 Emission Rtes Moisture quotient NH 4 NO 3 KNO 3 Control The Q vlue is lwys equl to or greter thn nd quntittively indictes the difference in the NH 3 voltiliztion rtes etween two soil moisture levels, ut it cnnot indicte the direction (positive or negtive) of difference ecuse Q is lwys. In contrst, AQ cn simultneously denote oth quntity nd direction of chnge ecuse it is either, equl to, less or greter thn. In this study, the AQ vlues were greter thn for ll of the soils except the BMS nd QFS soils mended with NH 4 NO 3. This suggests tht the low soil wter regime gretly enhnced the rte of NH 3 voltiliztion. Figure 9 shows tht the AQ vlues re temperture-dependent, nd t 29 C, single pek curve is otined. During the first week, nd y Dy 28, the AQ vlues were negtive. The curve intersects the X-xis on out Dy 7 nd Dy 28. This mens tht t these two points, the NH 3 voltiliztion rtes re the sme t oth 2% nd 8% FC. These two points cn e designted s isomoisture points (IMP) of NH 3 voltiliztion. The NH 3 voltiliztion rte t 8% FC ws greter thn tht t 2% FC when the AQ vlue ws negtive nd the converse is true when the AQ vlue ws positive. The resons for the demonstrtion of two IMPs my e severl. In the dys following ppliction of NH 4 NO Time (d) Fig. 8 The moisture quotient (Q) t 11 C for the rtes of mmoni voltiliztion from the four soils fertilized with five different N-sources under 2 nd 8% FC. BMS: Biscyne Mrl Soil; KGL: Krome Grvelly Lom; QFS: Quincy Fine Snd; nd WSL: Wrden Silt Lom

11 Wter Air Soil Pollut (27) 183: Active moisture quotient C 2 C 29 C Time (d) Fig. 9 The ctive moisture quotient (AQ) for the rtes of mmoni voltiliztion from the QFS soil mended with NH 4 NO 3 t 11, 2, or 29 C to the QFS soil, NH 3 voltiliztion progressed rpidly under oth soil wter regimes ut t slightly greter rte t 8% FC thn tht t 2%. This resulted in negtive AQ vlues. Susequently, s the NH4 þ ions from NH 4 NO 3 t 8% FC were trnsported into deeper soil nd dsored y the deeper soil prticles, the NH 3 emission decresed t 8% FC s compred to tht t 2%. This seemed to occur out 7 dys following incution (Fig. 9). As the NH4 þ source ws depleted fter out 14 dys, the NH 3 voltiliztion rte declined until out 28 dys (Fig. 9). For two of the tested soils mended with ll of N sources the AQ vlues were siclly greter thn the IMP, ut not for the BMS nd QFS soils mended with NH 4 NO 3.At 2 C, the AQ vlues incresed from Dy 7 through Dy 28 (Fig. 9). At 11 C, the AQ vlues were close to zero during the entire incution period. Hence t this low temperture, the NH 3 voltiliztion from the QFS soil mended with NH 4 NO 3 ws essentilly not influenced y the soil moisture regimes. At 11 C, NH 3 voltiliztion rtes were quite low from the BMS, KGL, nd WSL soils mended with (NH 4 ) 2 SO 4, (NH 2 ) 2 CO, or NH 4 NO 3, nd this rte ws lso low from the QFS soil mended with either of (NH 4 ) 2 SO 4 or (NH 2 ) 2 CO. Similrly, the BMS soil mended with NH 4 NO 3 hd one IMP t 11 C (Fig. 1) ut the other soils didn t hve IMP in this reserch. 4 Conclusion Mngement options to reduce NH 3 emissions from griculturl N fertilizer sources re highly desirle to minimize the negtive environmentl impcts ssocited with this form of N losses from griculturl uses of N fertilizers. The moisture quotient (Q) in this study ws the rtio of NH 3 emission rtes t 2 nd 8% FC. Thus, Q provides quntittive expression of effects of vrile soil wter regimes on NH 3 emission nd lso descries the dynmics of NH 3 emission over time. Results of this study reveled tht NH 3 voltiliztion ws significntly influenced y the N sources. Ammoni emission ws greter from the soils mended with (NH 4 ) 2 SO 4 or ure, s compred to tht of the soils mended with NH 4 NO 3. Low soil wter regime (2% FC) significntly incresed NH 3 voltiliztion cross ll N sources. The mximum Q vlues cross ll soils nd incution durtion were 19.3, 48.3 nd t 11, 2 nd 29 C, respectively. Furthermore, only the QFS soil mended with NH 4 NO 3 demonstrted two IMP points nd the BMS hd one IMP point indictive of similr NH 3 emission rtes t either 2 or 8% FC soil wter regimes. Ammoni emission from inorgnic N fertilizers used for griculturl production cn e minimized y mintining soil wter regime ner field cpcity level, prticulrly during the initil 1 14 dys following the N ppliction. Reduction in NH 3 emission from griculturl sources is le to improve ir qulity or, t lest, to minimize the deteriortion of ir qulity. In ddition to the environmentl enefits, decresing NH 3 emission Actve moisture quotient C 2 C 29 C Time (d) Fig. 1 The ctive moisture quotient (AQ) for the rtes of mmoni voltiliztion from the BMS soil mended with NH 4 NO 3 t 11, 2, or 29 C

12 126 Wter Air Soil Pollut (27) 183: from griculturl prctices economic enefits y wy of enhnced N uptke efficiency y minimizing gseous losses, which lowers the plnt ville N. Moreover, the reduction in NH 3 emission is eneficil to growers, since it should enhnce N uptke nd therey lower the cost of the N input. Acknowledgement This reserch ws supported y the Florid Agriculturl Experiment Sttion nd grnt from USDA-ARS. The uthors re gretly indeted to Dr. Wldemr Klssen nd Dr. Thoms Dvenport for their invlule comments nd suggestions to improve the mnuscript. References Asmn, W. A. H., Jonker, P. J., Slnin, J., & Brd, J. H. (1982). Neutrliztion of cid in precipittion nd some results of sequentil rin smpling. In: H. W. Georgii, J. Pnkrth (Eds.) Deposition of Atmospheric pollutnts.(pp ). Dordrecht, The Netherlnds: Reidel. Anej, V. A., Schlesinger, W. H., Niyogi, D., Jennings, G., Gillim, W., Knighton, R. E., et l. (26). Emerging ntionl reserch needs for griculturl ir qulity. EOS, 87(3), Anej, V. P., Murry, G. C., & Southerlnd, J. (1998). Atmospheric nitrogen compounds: Emissions, trnsport, trnsformtion, deposition nd ssessment. Environmentl Mnger, Boussingult, J. B. (1851). Die Lndwirtschft in ihren Beziehungen zur Chemie Physik und Meteorologie. Auflge II, Üersetzt von Greger H. Hlle, Verlg von Ch. Greger. Brn+Luee, AutoAnlyzer Applictions. Method No. US- 696D-82X. 125 Busch Prkwy, Bufflo Grove, IL 689. pp 1 6. Brunekreef, B., & Holgte, S. T. (22). Air pollution nd helth. Lncet, 36, Buijsmn, E., Ms, H. F. M., & Asmn, W. A. H. (1987). Anthropogenic NH 3 emissions in Europe. Atmospheric Environment, 21, Bussink, D. W., & Oenem, O. (1998). Ammoni voltiliztion from diry frming systems in temperte res: A review. Nutrient Cycling Agroecosystems, 51, Dentener, F. J. & Crutzen, P. J. (1994). A three-dimensionl model of the glol mmoni cycle. Journl Atmospheric Chemistry, 19, Dockery, D. W., Pope III, A., Xu, X., Spengler, J. D., Wre, J. H., Fy, M. E., et l. (1993). An ssocition etween ir pollution nd mortlity in six U.S. cities. New Englnd Journl of Medicine, 329(24), Duce, A. R., Liss, P. S., Merrill, J. T., Atls, E. S., But- Menrd, P., Hicks, B. B., et l. (1991). The tmospheric input of trce species to the world ocen. Glol Biogeochemicl Cycles, 5, Emerger, L. (1955). Afrique du nord-ouest. In: Plnt ecology: Review of reserch. Arid Zone Reserch, VI. Pris: UNESCO. pp EPA (1993). Ammoni nlysis method: USEPA 35.1, Revision 2., Methods for the determintion of inorgnic sustnces in environmentl smples. EPA-6/R Fngmeier, A., Hdwiger-Fngmeier, A., vn der Eerden L. J., & Jäger, H. (1994). Effects of tmospheric mmoni on vegettion - review. Environmentl Pollution, 86, FAO/IFA (21). Glol estimtes of gseous emissions of NH 3, NO nd N 2 O from griculturl lnd. Food nd Agriculture Orgniztion of the United Ntions (FAO)/ Interntionl Fertilizer Industry Assocition (IFA), Rome, 16. (Aville from Fenn, L. B., & Hossner, L. R. (1985). Ammoni voltiliztion from mmoni or mmonium-forming nitrogen fertilizers. In: Stewrt, B. A. (Ed.) Advnces in soil sciences. (pp ). Berlin Heidelerg New York: Springer. Fenn, L. B., & Miymoto, S. (1981). Ammoni loss nd ssocited rections of ure in clcreous soils. Soil Science Society of Americ Journl, 45, Ferm, M. (1998). Atmospheric mmoni nd mmonium trnsport in Europe nd criticl lods: A review. Nutrient Cycling in Agroecosystem, 51, Finlyson-Pitts, B. J., & Pitts, J. N. Jr. (1986). Atmospheric chemistry: Fundmentls nd experimentl techniques. New York: Wiley. Finlyson-Pitts, B. J., & Pitts, J. N. Jr. (2). Chemistry of the upper nd lower tmosphere (pp ; ). Sn Diego, CA: Acdemic. Fowler, S., Sutton, M., Flechrd, E., & Pitcirn, C. (1997). Ammoni sources, lnd-tmosphere exchnge nd effects: A Europen perspective. In: Proceedings of the Workshop on Atmospheric Nitrogen Compounds: Emissions, Trnsport, Trnsformtion, Deposition nd Assessment (pp ). Rleigh, NC: North Croline Stte University. Fox, R. H., & Hoffmn, L. D. (1981). The effect on N fertilizer source on grin yield, N uptke, soil ph, nd lime requirement in no-till corn. Agronomy Journl, 73, Gy, S. W., & Knowlton, K. F. (25). Ammoni emission nd niml griculture. Virgini Coopertive Extension/Biologicl Systems Engineering. Puliction pp He,Z.L.,Alv,A.K.,Clvert,D.V.,&Bnks,D.J.(1999). Ammoni voltiliztion from different fertilizer sources nd effects of temperture nd soil ph. Soil Science, 164, Hilhorst, M. A., Dirksen, C., Kmpers, F. W. H., & Feddes, R. A. (21). Dielectric relxtion of ound wter versus soil mtrix pressure. Soil Science Society of Americ Journl, 65, IPCC (The Intergovernmentl Pnel on Climte Chnge) (1996). In: Houghton, J. T., Meir, L. G., Filho, B., Cllnder, A., Hrris, N., Kttenerg, A., et l. (Eds.), Climte chnge 1995: The science of climte chnge. Cmridge, U.K: Cmridge University Press. Jckson, T. J., & Schmugge, T. J. (1989). Pssive microwve remote sensing system for soil moisture: Some supporting reserch. IEEE Trnsctions on Geosicience nd Remote Sensing, 27, Kelsll, J. E., Smet, J. M., Zeger, S. L., & Xu, J. (1997). Air pollution nd mortlity in Phildelphi, Americn Journl of Epidemiology, 146(9),

13 Wter Air Soil Pollut (27) 183: Kirchmnn, H., Esl, M., Morken, J., Fem, M., Bussink, W., Gustvsson, J., et l. (1998). Ammoni emissions from griculture. Nutrient Cycling Agroecosystem, 51, 1 3. Koorevr, P., Menelik, G., & Dirksen, C. (1983). Elements of soil physics: Developments in soil science. 13. Elsevier Science. Liu, G. D., Li, Y. C., & Alv, A. K. (27). High wter regime cn reduce mmoni voltiliztion from soils under potto production. Community Solutions, 38, (in press). Mrczzn, G. M., Vccro, S., Vlli, G., & Vecchi, R. (21). Chrcteriztion of PM1 nd PM2.5 prticulte mtter in the mient ir of Miln (Itly). Atmosphere Environment, 35, Muñoz-Crpen, R., Li., Y. C, & Olczyk, T. (25). Alterntives of low cost soil moisture monitoring devices for vegetle production in South Mimi-Dde County. Document ABE 333, Florid Coopertive Extension Service, Institute of Food nd Agriculturl Sciences, University of Florid. Njoku, R. W., & Entekhi, D. (1996). Pssive microwveremote sensing of soil moisture. Journl of Hydrology, 184, NRC (23). Air emissions from niml feeding opertions. Wshington, D.C.: The Ntionl Acdemies Press. Oliver, A. (1997). Dmpness in uildings. 2nd edition revised y Dougls, J. nd Stirling, J. S., Blckwell Science, Oxford, UK. Pgno, P., de Zicomo, T., Scrcell, E., Bruni, S., & Clmosc, M. (1998). Mutgenic ctivity of totl nd prticle-sized frction of urn prticulte mtter. Environmentl Science nd Technology, 3, Perl, H. W. (1991). Ecophysiologicl nd trophic implictions of light simulted mino cid utiliztion in mrine picoplnkton. Applied Environmentl Microiology, 57, Perl, H. W. (1995). Costl eutrophiction in reltion to tmospheric nitrogen deposition: Current perspectives. Opheli, 41, Schlesinger, W. H., & Hrtley, A. E. (1992). A glol udget for tmospheric NH 3. Biogeochemistry, 15, Schwrtz, J., Dockery, D. W., & Nes, L. M. (1996). Is dily mortlity ssocited specificlly with fine prticles? Journl of Air & Wste Mngement Assocition, 46, Sommer, S. G., Schjoerring, J. K., & Denmed, O. T. (24). Ammoni emission from minerl fertilizers nd fertilized crops. Advnces in Agronomy, 82, Sprengel, C. (1839). Die Lehre vom Dünger. Verlg J. Müller, Leipzig. pp Vn Breemn, N., Burrough, P. A., Velthorst, E. J., Vn Doen, H. F., De Wit, T., Ridder, T. B., et l. (1982). Soil cidifiction from tmospheric sulphte in forest cnopy through-fll. Nture, 299, Vzquez-Rodriguez, G. A., & Rols, J. L. (1997). Study of the nitrifiction process with ctivted sludge: inhiiting effect of mmoni on nitrifying cteri. Revue des Sciences de l Eu, 1, Viitnen, H. (1997). Criticl time of different humidity nd temperture conditions for the development of rown rot decy in pine nd spruce. Holzforschung, 51(2), Vlek, P. L. G., & Crter, M. F. (1983). The effect of soil environment nd fertilizer modifictions on the rte of ure hydrolysis. Soil Science, 136, Voutilinen, J. (25). Methods nd instrumenttion for mesuring moisture in uilding structures. Disserttion for degree of Doctor of Science t Helsinki University of Technology, Espoo, Finlnd. Wrneck, P. (1999). Chemistry of the nturl tmosphere (pp. 1 95). London: Acdemic.