Ammonium fixation and release by clay minerals as influenced by potassium

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1 Plnt Soil Environ. Vol. 6, 21, No. 7: Ammonium fixtion n rls y ly minrls s influn y potssium H.W. Shrr, E. Fils, P. Butrs Dprtmnt of Plnt Nutrition, Institut of Crop Sin n Rsour Consrvtion, Univrsity of Bonn, Bonn, Grmny ABSTRACT It is postult tht stiliz mmonium frtilizrs improv frtilizr-n utiliztion y rops, ling thus to highr yils with th sm frtilizr rt, spilly on sny soils. Howvr, it must tkn into onsirtion tht in lyy soil t lst prt of th NH ions my fix y 2:1 ly minrls, thus lying th fft of th N frtilizr. Bus NH n K hv similr siz n vln proprtis n thrfor ompt for th sm non-xhngl sits of 2:1 ly minrls, w invstigt th influn of tim n K pplition rt on oth fixtion n rls of NH. Fixtion of NH ions ws highr whn K ws ppli ftr NH, whil th influn of th K pplition rt ws lss pronoun. Moiliztion of non-xhngl NH ws rtr whn K ws ppli t th high rt ftr NH. At th first hrvst yil formtion of rygrss ws nithr influn y th mount s wll s th pplition tim of K, us plnt vill N ws not growth limiting, whil yil of th son hrvst ws signifintly highr with th low K pplition rt ftr NH. Aftr th son hrvst th loking fft of K on th rls of non-xhngl NH ws ttnut n th highst yils of th thir ut wr rh in th trtmnts with th high K pplition rt ftr NH. Totl ry mttr yil ws highst whn K ws ppli t th low rt ftr NH. Our rsults show tht K govrns fixtion n rls of non-xhngl NH, whih shoul tkn into onsirtion whn pplying mmonium ontining N frtilizrs lik mmonium sulft, mmonium sulft nitrt n ENTEC. Thus K n fft N vilility whn N is ppli s NH in oth th short n long trm. Kywors: nitrogn; vilility; potssium; ly minrls; rop yil From ll plnt nutrints N srvs th highst ttntion. Whil too low rts my prss th profit, too high rts my rsult in nitrt lhing (Mngl t l. 26). Aoring to Pltonn-Sinio n Pltonn (199) unr fvourl onitions N pplition lon in spring my suffiint to promot plnt growth, ut my rsult in insuffiint N vilility uring grin filling. For this rson th splitting of th nitrogn pplition rt is rommn for n ffiint us of frtilizr-n (Lópz-Bllio t l. 212). Nvrthlss in th lst yrs n inrsing iffus nitrt loing of surf wtr n grounwtr hs mrg s mjor prolm in mny griulturl rs of th worl, rsulting in ontmintion of rinking wtr rsours (Silo t l. 213). An option to minimiz nitrt lhing is th us of mmonium-ontining N frtilizrs. Howvr, in soils mmonium my onvrt into moil nitrt ions within short prio of tim. Thrfor nitrifition inhiitors stiliz N frtilizrs, for xmpl, mmonium sulpht nitrt with th nitrifition inhiitor 3,-imthylpyrzol phospht (DMPP), wr introu (Di n Cmron 22, Bnkisr t l. 213). Controlling th miroiologil pross of nitrifition, nitrt losss oul ru y inrsing th ssimilt N y plnts (Suro t l. 26). In Amri n Asi mmonium-s frtilizrs hv n inrsingly us (Pru`homm 25). Howvr, thir rovry ffiiny oul influn y fixtion n rls of NH y 2:1 ly Support y th Dutsh Forshungsgminshft (DFG), Projt No. SCHE 312/23-1 (FOR 132) 325

2 Vol. 6, 21, No. 7: Plnt Soil Environ. minrls. In soils with high mmonium fixtion pity, t lst prt of th NH suppli s frtilizr my oun in ly minrl intrlyrs (Tng t l. 28). Th shr of NH fix pns on th NH fixtion pity of th soil (Shrr 1993). Kowlnko (1978) rport tht 59% of 152 kg N/h s (NH ) 2 SO wr fix. In th s of NH stiliz frtilizrs th pross of NH fixtion my prolong n th shr of fix NH is ssum to vn highr. NH fixtion y ly minrl intrlyrs lso pns on th K sttus of th soil. If th K onntrtion of th soil solution is high or inrs y K frtilizr pplition, it n xpt tht th intrlyr sp is lso sturt with K (Shrr 1982), rsulting in rs NH fixtion. Othrwis K my imp th rls of NH ions, whih my u to th loking fft of K ions (Nir t l. 211). Thrfor, whn pplying NH stiliz frtilizrs intrtions twn NH n K ions shoul tkn into onsirtion. Howvr, no ttmpts hv n m to onsolit th frgmnt informtion on th ffts of K on fixtion n rls of NH ions. For this rson th spifi ojtivs of this stuy wr to trmin th influn of point of tim n mount of K pplition on th fixtion of NH stiliz n onvntionl NH ontining N frtilizr, s wll s on yil n N uptk of rygrss. MATERIAL AND METHODS Th susoil (3 75 m) from Luvisol riv from loss with ly ontnt of 23.9% n xpnl illit s th min ly minrl ws hosn for th xprimnt. Th initil ontnt of nonxhngl NH -N ws 115 mg/kg n plnt vill K 133 mg/kg soil. Fourtn trtmnts (h with four rplitions) wr stlish (Tl 1). Nitrogn (25 mg/kg soil) ws ppli s: soium nitrt (NNO 3 ), mmonium sulft (AS), ENTEC 26 (mmonium sulft nitrt 3,-imthylpyrzol phospht) n mmonium sulft nitrt (ASN). K ws ppli s K 2 SO in two pplition rts (K1 25 mg/kg soil, rfrr to low K; K2 5 mg/kg soil, rfrr to high K). Aftr thoroughly mixing N n K, rsptivly, into th soil (< mm) th wtr ontnt ws just to 6% of th mximum wtr holing pity with ioniz wtr n pr-inut for 7 ys. Aftrwrs th soil smpls wr ri t C in n ovn, pss through mm siv n N n K inorport into th soil in rvrs orr (Tl 1). In th following inution prio soil smpls wr stor gin for 7 ys ftr justing th mximum wtr holing pity of 6%. Th tmprtur uring pr-inution n inution rng twn 2 C n 25 C. NNO 3 ws suppli togthr with K. Th ottom of th xprimntl pots wr fill with 6 kg soil suppli with. g P s C(H 2 PO ) 2 H 2 O n. g Mg s.6 g MgSO 7 H 2 O s sl frtilizrs, follow y 3 kg prtrt soil (rfrr s topsoil) oring to Tl 1. Aftr plnting of rygrss (Lolium multiflorum v. Arin) th soil wtr ontnt ws just to 6% of th mximum wtr holing pity n ontroll ily to rplnish wtr loss with ioniz wtr. Rygrss ws ut thr tims, ri in n ovn t 15 C n ry-mttr yil trmin. Aftr grining totl N ws nlyz using th Dums omustion mtho. Aftr h hrvst soil smpls wr tkn from th topsoil with n ugr (thr ors pr pot). Th smpls from h pot wr pool, ir ri n pss through 1 mm siv. Non-xhngl NH -N ws nlyz oring to Butrs n Tl 1. Trtmnts Trtmnt N form Prinution Inution N K N K 1 NNO 3 K1 2 NNO 3 K2 3 AS K1 AS K2 5 ENTEC 26 K1 6 ENTEC 26 K2 7 ANS K1 8 ANS K2 9 AS K1 1 AS K2 11 ENTEC 26 K1 12 ENTEC 26 K2 13 ANS K1 1 ANS K2 NNO 3 soium nitrt; AS mmonium sulft; ENTEC 26 mmonium sulft nitrt 3,-imthylpyrzol phospht; ASN mmonium sulft nitrt; K1 25 mg/kg soil; K2 5 mg/kg soil 326

3 Plnt Soil Environ. Vol. 6, 21, No. 7: Shrr (212). Aftr prtrting th soil smpl with KOBr solution n rying t 6 C for 2 h non-xhngl NH -N ws trmin with n lmntl nlyzr with thrml onutivity ttor. Plnt vill K ws msur ftr xtrtion with.1 mol/l lium tt.1 mol/l lium ltt.3 mol/l ti i with soil:xtrt rtio of 1:2 ftr shking for 2 h (Shüllr 1969). Sttistil nlysis. Multivrit nlysis (ANOVA) ws prform using th SPSS 2 softwr pkg (Chigo, USA). Mns wr ompr t signifin lvl of P =.5 y th Tuky s tst. Stnr vition vlus r pit in th grphs s rs. RESULTS At th first hrvst th influn of th kin of N frtilizr s wll s th pplition tim n mount of ppli K on yil of rygrss ws ngligil (Figur 1). At th son hrvst th influn of th N form n mount of K ppli ws lso mrginl, whn K ws ppli for N. Howvr, ompring th trtmnts K ftr N, yils wr signifintly highr with K1 (Figur 1). At th thir hrvst th influn of th mount of K ppli on yil formtion ws gin ngligil whn K ws ppli for N, whil whn K ws ppli ftr N, in ontrition to th son hrvst, yil ws highst in th trtmnts with K2 (Figur 1). N uptk of th first hrvst ws on th sm lvl whn K ws ppli t th low K pplition rt for or ftr N. Whn K ws ppli ftr N, K2 rsult in signifint rs N uptk. N uptk ws signifintly lowst with N s AS (Figur 2). Inpnnt of th N form N uptk of th son hrvst ws mostly signifintly lowr whn K ws ppli for N s ompr to K ftr N. As ompr to th first hrvst th influn of th mount of ppli K on N uptk rs whn K ws ppli ftr N (Figur 2). At th thir hrvst N uptk ws signifintly highst whn K2 ws ppli ftr N. Btwn ths trtmnts N uptk ws signifintly highst with AS (Figur 2). Bfor th strt of th xprimnt th soil ontin 115 mg non-xhngl NH -N/kg (Figur 3) n ws not influn y th pplition of NNO 3, ut inrs ftr th inorportion of th mmonium ontining frtilizrs. Th inrs ws lowr in th trtmnts whn K ws ppli for. Howvr, th influn of th iffrnt mmonium ontining frtilizrs s wll s th () DM yil (g/pot) () DM yil (g/pot) () DM yil (g/pot) NNO 3 simultn for ftr NNO 3 simultn for ftr Figur 1. Dry mttr (DM) yil of th first (), son () n thir hrvst of rygrss (). Diffrnt lttrs init signifint iffrns (P <.5) mong th trtmnts. K rt: K1 25 mg/kg soil; K2 5 mg/kg soil; N form: NNO 3 soium nitrt; AS mmonium sulft; ENTEC 26 mmonium sulft nitrt 3,-imthylpyrzol phospht; ASN mmonium sulft nitrt; tim of K pplition: simultn, for n ftr 327

4 Vol. 6, 21, No. 7: Plnt Soil Environ. () N uptk (mg/pot) () N uptk (mg/pot) () N uptk (mg/pot) K1 K2 K1 K2 K1 K2 K1 K2 K1 K2 K1 K2 K1 K2 NNO 3 simultn for ftr NNO 3 simultn for ftr Figur 2. N uptk of th first (), son () n thir hrvst of rygrss (). Diffrnt lttrs init signifint iffrns (P <.5) mong th trtmnts. K rt: K1 25 mg/kg soil; K2 5 mg/kg soil; N form: NNO 3 soium nitrt; AS mmonium sulft; ENTEC 26 mmonium sulft nitrt 3,-imthylpyrzol phospht; ASN mmonium sulft nitrt; tim of K pplition: simultn, for n ftr mount of ppli K ws ngligil. Also whn K ws ppli ftr th mmonium ontining () Non-xhng. NH -N (mg/kg soil) () frtilizrs NH fixtion ws not influn y th K pplition rt. Th NH fixtion rt ws Non-xhng. NH -N (mg /kg soil) () Non-xhng. NH -N (mg/kg soil) () Non-xhng. NH -N (mg/kg soil) f f f f f NNO 3 simultn for ftr Figur 3. Contnts of non-xhngl NH -N ftr soil inution () n ftr th first (), son () n thir hrvst () of rygrss. Diffrnt lttrs init signifint iffrns (P <.5) mong th trtmnts. K rt: K1 25 mg/kg soil; K2 5 mg/kg soil; N form: NNO 3 soium nitrt; AS mmonium sulft; ENTEC 26 mmonium sulft nitrt 3,-imthylpyrzol phospht; ASN mmonium sulft nitrt; tim of K pplition: simultn, for n ftr K N NNO 3 t simultn for ftr 328

5 Plnt Soil Environ. Vol. 6, 21, No. 7: highst in th s of (NH ) 2 SO. Btwn th strt of th xprimnt n th first hrvst th ontnt of non-xhngl NH -N inrs in oth NNO 3 trtmnts, whil in most of th othr trtmnts non-xhngl NH -N ws moiliz. Until th first hrvst moiliztion ws highst whn ASN ws ppli for K (Figur 3). Aftr th first hrvst until to th son hrvst th influn of tim n mount of K pplition on NH moiliztion ws ngligil, whn K ws ppli for N, xpt in th trtmnt whn K ws ppli ftr ASN t th high rt. In th trtmnts whn K ws ppli ftr N, moiliztion of non-xhngl NH -N ws signifintly lowr t th high K pplition rt (Figur 3). Aftr th son hrvst th influn of th K pplition rt on th ontnt of nonxhngl NH -N ws ngligil whn K ws ppli for N. Howvr, th high K pplition rt ftr NH rsult in signifintly highr ontnt of non-xhngl NH -N s ompr to th trtmnts with th low K pplition rt (Figur 3). Aftr trting th soil with N n K inpnnt of th tim of K pplition th ontnt of plnt vill K ws lwys highr with th high K pplition rt. In th onomitnt N frtilizr trtmnt th ontnt of plnt vill K ws highr whn K ws ppli ftr NH (Figur ). Aftr th first hrvst th ontnt of plnt vill K ws signifintly highst in th trtmnts with th high K pplition rt ftr NH (Figur ) whil ftr th son (Figur ) n thir hrvst (Figur ) th ontnt of plnt vill K ws signifintly highr with th high K pplition rt inpnnt of th tim of K pplition. DISCUSSION Frquntly lim vntgs for th us of N frtilizrs stiliz with nitrifition inhiitors r yil inrss (Woznik t l. 1997). Howvr, oring to Ps t l. (21) th yil-inrsing fft of DMPP, hving urtion tim twn 6 () Plnt vill K (mg K/kg soil) () () Plnt vill K (mg K/kg soil) () Plnt vill K (mg K/kg soil) NNO 3 simultn for ftr K K N tz K NNO 3 N simultn for ftr t Figur. Plnt vill K ftr soil inution () n ftr th first (), son () n thir hrvst () of rygrss. Diffrnt lttrs init signifint iffrns (P <.5) mong th trtmnts. K rt: K1 25 mg/kg soil; K2 5 mg/kg soil; N form: NNO 3 soium nitrt; AS mmonium sulft; ENTEC 26 mmonium sulft nitrt 3,-imthylpyrzol phospht; ASN mmonium sulft nitrt; tim of K pplition: simultn, for n ftr 329

6 Vol. 6, 21, No. 7: Plnt Soil Environ. to 8 wks (Villr n Guillums 21), is strongr th lightr th soil. Whn pplying mmonium stiliz N frtilizrs to hvy soils it must rogniz tht t lst prt of th NH ions my fix y ly minrls, rsing th momntry N vilility for plnts. Using soil with high fixtion pity w foun tht lmost ll of th mmonium ppli with AS ws fix y ly minrls uring th inution of th soil, whn N ws ppli for K. As ompr with AS, fixtion of NH ws lowst with ASN, whil ENTEC 26 ws rnging in twn. Bus Ps t l. (21) foun tht t 2 C, nitrifition of ASN ws omplt within 7 to 21 ys, s ompr to ys with DMPP, w ssum tht th lowst fixtion in our xprimnt ws us y prtil nitrifition of non-stiliz mmonium of ASN uring th inution prio of th soil. As rsult of omptition for fixtion sits (Buhmp 1982) pplying K for NH ontining N frtilizrs rsult in rs NH fixtion, with mn rs of out 2%. This is in orn with th rsults of Brtltt n Simpson (1967) showing tht K pr-ition prss NH fixtion y oupying intrlyr positions of 2:1 ly minrls. As xpt ftr pplying NNO 3 th inrs of non-xhngl NH -N ws ngligil. Howvr, ftr th first hrvst stp inrs of this N frtion ws osrv, ssuming tht th NH ions r riv from minrliztion of soil orgni mttr (Tng t l. 28). As xpt inpnnt of th tim of K pplition th ontnt of plnt vill K ws highr with th high K pplition rt. Howvr, th tim of K pplition ws of prim importn rsulting in highr ontnts of plnt vill K whn K ws ppli ftr NH, us s rsult of omptition for th sm fixtion sits lss intrlyr sp ws vill for K (Shrr 1982). Stffns n Sprks (1997) sri th kintis of moiliztion of non-xhngl NH -N from ly minrls y th Elovih mol. Whthr non-xhngl NH -N n rls pns on th onntrtion grint of NH in th intrlyrs n soil solution (Tng t l. 28). Howvr, Nommik (1957) suggst tht lso K shoul introu into th quilirium qution. Thrfor th influn of K oms of prtil importn (Axly n Lgg 196, Škrp n Hlušk 212). Whn th ontnt of plnt vill K is high s in our trtmnts K ftr NH, it my ssum tht lso th g positions of th ly minrls r oupi y K, hinring th iffusion of NH ions out of th intrlyrs. In ftr th son n thir hrvst, th ontnt of non-xhngl NH -N ws highr in th trtmnts with th high K pplition rt ftr NH. At th first hrvst th influn of th mount s wll s th pplition tim of K on yil formtion ws ngligil, us plnt vill N ws not growth limiting. Howvr, yil of th son hrvst ws signifintly highst with th low K pplition rt ftr NH. W ssum tht in th mn K ions, minly lot t th g position of th ly minrl intrlyrs, wr moiliz n th loking fft of K iminish, fvouring th rls of non-xhngl NH -N. With th high K pplition rt th rls of non-xhngl NH -N ws still lok n N uptk ws signifintly lowr, onfirming tht K govrns th rls of non-xhngl NH -N (Wlh n Sott 196) n thrfor yil formtion. Aftr th son hrvst th loking fft of K on th rls of non-xhngl NH -N sms to ovrom n highst yils of th thir hrvst wr now rh in th trtmnts with th high K pplition rt ftr NH. Clulting totl yil (sum of thr hrvsts) thr is vin tht th K pplition rt hs no impt on th vilility of non-xhngl NH -N whn K is ppli for mmonium ontining frtilizrs. Howvr, whn K ws ppli ftr mmonium ontining frtilizrs totl yil ws signifintly highr with K1. Although ontinuous uptk of K ions ru th K onntrtion n iminish th loking fft on th rls of NH (Nir t l. 211) th K onntrtion in th trtmnts with K2 ws still too high to ovrom th loking fft. Thrfor th sttmnt of Ps t l. (21) tht N frtilizrs omin with DMPP my improv yils of griulturl rops n vgtls must osrv in mor tils. Bsis yil formtion totl N uptk ws signifintly lowr with th high K pplition rt ftr mmonium-ontining frtilizrs. Th prssion of N uptk t th first hrvst oul not ompnst y th highr N uptk of th thir hrvst. Th mn totl N uptk ws lowr y out 25%. Thrfor from prtil point of viw N frtilizrs with high shr of mmonium shoul not ppli for potssium to soils with n ppril fixtion pity (Axly n Lgg 196). 33

7 Plnt Soil Environ. Vol. 6, 21, No. 7: Aknowlgmnts Th uthors r muh int to th Dutsh Forshungsgminshft (DFG), Projt No. SCHE 312/23-1 (FOR 132) n to Prof. Dr. Ulrih Köpk s th inititor of th projt. REFERENCES Axly J.H., Lgg J.O. (196): Ammonium fixtion in soils n th influn of potssium on nitrogn vilility from nitrt n mmonium sours. Soil Sin, 9: Brtltt R.J., Simpson T.J. (1967): Intrtion of mmonium n potssium in potssium-fixing soil. Soil Sin Soity of Amri Journl, 31: Buhmp E.G. (1982): Fix mmonium n potssium rls from two soils. Communitions in Soil Sin n Plnt Anlysis, 13: Bnkisr G., Christ E., Hrrt T., Wisk A., Blom J., Hrt M. (213): Th nitrifition inhiitor 3,-imthylpyrzolphospht (DMPP) quntifition n ffts on soil mtolism. Plnt n Soil, 37: Di H.J., Cmron K.C. (22): Th us of nitrifition inhiitor, iynimi (DCD), to rs nitrt lhing n nitrous oxi missions in simult grz n irrigt grssln. Soil Us n Mngmnt, 18: Butrs P., Shrr H.W. (212): Moifition of th stnr mtho for trmintion of non-xhngl NH -N in soil. Plnt, Soil n Environmnt, 58: Kowlnko C.G. (1978): Nitrogn trnsformtions n trnsport ovr 17 months in fil fllow miroplots using 15 N. Cnin Journl of Soil Sin, 58: Lópz-Bllio L., Munoz-Romro V., Bnítz-Vg J., Frnánz- Grí P., Rono R., Lópz-Bllio R.J. (212): Wht rspons to nitrogn splitting ppli to Vrtisol in iffrnt tillg systms n ropping rottions unr typil Mitrrnn limti onitions. Europn Journl of Agronomy, 3: Mngl K., Hütsh B., Kn Y. (26): Nitrogn frtilizr pplition rts on rl rops oring to vill minrl n orgni soil nitrogn. Europn Journl of Agronomy, 2: Nir R., Bni D.K., Shrr H.W. (211): Fixtion n fixtion of mmonium in soils: A rviw. Biology n Frtility of Soils, 7: 1 1. Nommik H. (1957): Fixtion n fixtion of mmonium in soils. At Agriultur Sninvi, 7: IGINAL PPER Ps G., Hähnl R., Zrull W. (21): Efft of frtilizrs with th nw nitrifition inhiitor DMPP (3,-imthylpyrzol phospht) on yil n qulity of griulturl n hortiulturl rops. Biology n Frtility of Soils, 3: Pltonn-Sinio P., Pltonn J. (199): Progrss sin th 193s in ring for yil, its omponnts, n qulity trits of spring wht in Finln. Plnt Bring, 113: Pru`homm M. (25): Glol nitrogn frtilizr supply n mn outlook. Sin in Chin. Sris C, Lif Sins, 8: Shrr H.W. (1982): Fix NH -N in rltion to EUF-xtrtl K. Plnt n Soil, 6: Shrr H.W. (1993): Dynmis n vilility of th non-xhngl NH -N A rviw. Europn Journl of Agronomy, 2: Shüllr H. (1969): Th CAL-mtho, nw mtho for th trmintion of th plnt vill phospht in soils. Zitshrift für Pflnznrnährung un Bonkun, 123: (In Grmn) Silo M., Myr B., Niolrot B., Piny G., Mriotti A. (213): Long-trm ft of nitrt frtilizr in griulturl soils. Proings of th Ntionl Amy of Sin of th Unit Stts of Amri, 11: Škrp P., Hlušk J. (212): Efft of yrs, frtiliztion n growing rgions on th ontnt n forms of potssium in soil. Journl of Elmntology, 17: Stffns D., Sprks D.L. (1997): Kintis of nonxhngl mmonium rls from soils. Soil Sin Soity Amrin Journl, 61: Suro G.V., Ito O., Shrwt K.L., Brry W.L., Nkhr K., Ishikw T., Wtn T., Sung K., Ronon M., Ro I.M. (26): Sop n strtgis for rgultion of nitrifition in griulturl systms Chllngs n opportunitis. Critil Rviws in Plnt Sin, 25: Tng V., Wng X.-Z., Zho H.-T., Fng K. (28): Efft of potssium n C/N rtios on onvrsion of NH in soils. Posphr, 18: Villr J.M., Guillums E. (21): Us of nitrifition inhiitor DMPP to improv nitrogn rovry in irrigt wht on lrous soil. Spnish Journl of Agriulturl Rsrh, 8: Wlh L.F., Sott A.D. (196): Nitrifition of fix mmonium in ly minrls s fft y potssium. Soil Sin, 9: Woznik H., Fuhs M., Mihl H.J. (1997): N-stiliztion Invstigtions out th us of nitrifition inhiitors in griulturl rops. VDLUFA-Shriftnrih Kongrssn, 6: (In Grmn) Riv on Mrh 1, 21 Apt on My 1, 21 Corrsponing uthor: Prof. Dr. Hinrih W. Shrr, Univrsity of Bonn, Institut of Crop Sin n Rsour Consrvtion, Dprtmnt of Plnt Nutrition, Krlrort-Kritn-Strß 13, Bonn, Grmny phon: , fx , -mil: h.shrr@uni-onn. 331

Dinitrogen fixation and residue nitrogen of different managed legumes and nitrogen uptake of subsequent winter wheat

Dinitrogen fixation and residue nitrogen of different managed legumes and nitrogen uptake of subsequent winter wheat Dinitrogn fixtion n rsiu nitrogn of iffrnt mng lgums n nitrogn uptk of susqunt wintr wht R. Logs 1, A. Ksk 2 n F. Tu 2 1 Dprtmnt of Orgni Frming, Univrsity of Kil, 2 Dprtmnt of Grss n Forg Sin, Univrsity