THE AVAILABILITY OF MINERAL NITROGEN IN MEDITERRANEAN OPEN STEPPE DOMINATED BY STIPA TENACISSIMA L.

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1 ACTA UNIVERSITATIS AGRICULTURAE ET SILVICULTURAE MENDELIANAE BRUNENSIS Volume LIX 22 Numer 5, 2011 THE AVAILABILITY OF MINERAL NITROGEN IN MEDITERRANEAN OPEN STEPPE DOMINATED BY STIPA TENACISSIMA L. I. Novosádová, J. Záhor, J. D. R. Sinog Received: April 12, 2011 Astrct NOVOSÁDOVÁ, I., ZÁHORA, J., RUIZ-SINOGA, J. D.: The vilility of minerl nitrogen in Mediterrnen open steppe dominted y Stip tencissim L. Act univ. gric. et silvic. Mendel. Brun., 2011, LIX, No. 5, pp The re of interest is locted in the Sierr de los Filres in semi-rid steppe of the province of Almeri in Spin. The mount of wter in the soil is limiting fctor nd its vilility ffects the structure nd species composition of ecosystem. On the other hnd, the type of vegettion ffects the wter loss vi evpotrnspirtion nd thus the soil microclimte. It hs gret influence on the growth nd ctivity of soil microil communities nd hence the dynmics of decomposition of orgnic mtter nd nutrient vilility. The im of this study ws to ssess the intensity of microil trnsformtions of soil orgnic nitrogen nd descrie chnges in the content of nitrogen minerl forms t different depths in the semi-rid climte soil in the Mediterrnen region. Avilility nd movement of nitrogen ws monitored y cpturing the minerl nitrogen into the structures of ion exchnge resin pplied to the soil in three different vrints (control vrint, vrint with the ddition of cellulose, nd the vrint with the ddition of rw silk). Ion exchnge resins hve een instlled into soil profile in 2008, 2009, nd After the in situ exposure the ion exchnge resins were removed from the soil profile nd the quntity of cptured minerl N ws determined y distilltion titrtion method. The vilility of mmoni-nitrogen ws significntly ffected y the ddition of different sustrtes minly y the dditions of the rw silk, where the vilility ws regulrly the highest. However, the vilility of mmoni-nitrogen form ws generlly higher thn the vilility of nitrte form. Mediterrnen soil, minerl nitrogen, microil trnsformtions, ion exchnge resin The microil ctivity plys n importnt nd key role in the soil processes; first of ll in the trnsformtion of different orgnic compounds entering the soil milieu, in the formtion of persistent soil orgnic mtter nd in the sustinle relesing of the nutrients. Also soil fun my sustntilly ffect the living conditions of microflor nd thus indirectly ffect microil ctivity (Frouz nd Nováková, 2005). The soil microil iomss is lile pool of orgnic mtter nd comprises 1 3% of totl soil orgnic mtter. The soil microil iomss cts s source nd sinks of the plnt nutrient nd regultes the functioning of the soil system (Kur et l., 2000). These source-sink dynmics depend on complex interctions etween climte, topogrphy, vegettion nd soil surfce properties (Mestre, 2006). Plnt cover through its effects on the quntity nd qulity of orgnic mtter inputs influences the levels of soil microil iomss (Kur et l., 2000). The nutrient relese processes hve fundmentl role in ecosystem functioning, prticulrly in Mediterrnen res, where nutrient vilility, minly nitrogen, represents limiting fctor (Rutiglino et l., 2009). However, in soil with less nitrogen the nutrient cycle is suject of strict iologicl control. Plnt litter is ttcked y decomposers, nd lmost ll the nitrogen it releses is immeditely immoilized y microorgnisms. In Mediterrnen res the nutrient vilility is lso closely linked to wter vilility in the soil. 187

2 188 I. Novosádová, J. Záhor, J. D. R. Sinog This strong link etween N vilility nd wter use efficiency mkes prticulrly importnt the understnding of fctors ffecting soil N vilility in Mediterrnen ecosystem in view of the future predicted incresing drought in this re (Rutiglino et l., 2009). Open steppes dominted y tussock grss Stip tencissim constitute one of the mjor vegettion types in the driest res of the Mediterrnen sin. Stip tencissim steppes re good model systems in rid lnd ecology, s the vegettion ptterns nd the processes governing their functioning resemle those descried in rid nd semirid regions throughout the world (Mestre, 2006). The im of this study ws to ssess the intensity of microil trnsformtions of soil orgnic nitrogen nd descrie chnges in the content of nitrogen minerl forms in different depths of the Mediterrnen soil which is influenced y tufts of grss Stip tencissim. MATERIALS AND METHODS The experimentl plots were situted etween m.s.l in Almerí which is province of Autonomous Community of Andlucí, Spin. These re extent of m 2 nd is locted in Sierr de los Filres Mountins. The men nnul rinfll of the region is of out 240 mm mostly concentrted in utumn nd spring which is common in semirid Mediterrnen climte. The men nnul temperture is 13.9 C. The studied soil, clssified s Lithosol, hs lom to sndy cly texture (FAO-ISRIC nd ISSS, 1998) nd ph 6.5 nd content of orgnic mtter 1.6%. The vegettion cover of these res is n open steppe dominted y Stip tencissim L. (coverge of up to 75%). The vilility (more or less in the cse of mmoni-nitrogen) nd movement of percolted nitrogen (minly in the cse of nitrte-nitrogen) ws estimted in situ ccording to Binkley t Mtson (1982) y the trpping of minerl N into the ion exchnge resin (IER) inserted into two different types of specil cover. Ion exchnge resin stockings were prepred y plcing ion exchnge resin (CER, ction exchnge resin No. Purolite C100E, nd AER, nion exchnge resin no. Purolite A520E) in cylindricl stockings (0.9 cm dimeter y 21.3 cm long), mde of fine nylon mesh (grid size of 42 μm) which were then stpled shut. The stockings contined either 11.2 g moist weight ction exchnge resin (13.7 ml, 5.4 g dry weight) or 9.3 g moist weight nion exchnge resin (13.7 ml, 4.9 g dry weight). Exchnge sites of IER were sturted with Cl nd N + ions. The first set of CER- nd AERstockings were prepred for insertion into the soil s control vrint. Second set of stockings were coted with pure cellulose s the source of cron nd third set were coted with rw silk s the source of oth, cron nd nitrogen to support microil ctivities. The first types of prepred IER stockings (gs) were rndomly inserted into cylindricl holes (1.0 cm dimeter) in the experimentl plots. The holes were prepred y pushing metl rode into soil profile t 45 ngle to soil depth of 15 cm (Fig. 1). This ion exchnge resin gs cn e plced into soil with miniml soil disturnce. This type of IER stocking were inserted to the soil on the reserch plce in 12 repetitions. Another set of specil nnulr flt cover (disc) for estimtion of the movement of inorgnic nitrogen ws mde from PVC tues (dimeter 7 cm, thickness 4 cm). Nylon mesh (grid size of 0.1 mm) ws stuck on the PVC ring. Mixed IER (CER nd AER in rtio 1:1) were then plced into the inner spce of nnulr flt cover (Fig. 2). The nnulr flt IER cover ws inserted into the soil in the depth of 30 cm in the experimentl plot in 30 repetitions. Accumultion of N took 24-week over the 36 month period nd it included wet seson (Octoer April) nd dry seson (My Septemer). For the quntifiction of NH 4+ -N nd NO 3 -N trpped y the resin, the IER were llowed to dry t room temperture. Asored NH 4+ -N nd NO 3 N were evluted from IER using 100 ml 1.7 M NCl nd determined y distilltion nd titrtion method (Peoples et l., 1989). Results from the ion exchnge resin gs were expressed s mg of NH 4+ -N.10 ml 1 IER nd NO 3 -N.10 ml 1 IER. The results from the ion exchnge resin discs were expressed s mg NH 4+ -N.m 2 nd NO 3 -N.m 2. Sttisticl evlution 1: Scheme of ppliction of ion exchnge resin (IER) in the first type of specil cover, in fine nylon stockings 2: Second type of specil cover - nnulr flt ion exchnge resin cover which were inserted into the soil in the depth of 30

3 The vilility of minerl nitrogen in Mediterrnen open steppe dominted y Stip tencissim L. 189 ws performed y mens of nlysis of vrince (ANOVA P < 0.05). When compring the mens, the Tukey s HSD procedure ws used s multiple rnge tests. RESULTS AND DISCUSSION Presented experiments re sed on the estimtion of nitrogen ion moility nd trnsport using ion cpture into the structure of resin gs. The sensitivity of the resin g method to ion moility nd trnsport my e useful for ssessing N vilility to plnt roots, ecuse the driving forces which ffected the cptured mount into the resin gs re nerly the sme s in the cse of nutrient uptke y roots (Binkley, 1984). There exist severl experiments sed on using ion exchnge resin in lortory conditions ut the lortory incutions cnnot reflect chnges in temperture nd moisture tht occur in the field, which re crucil for the nutrient vilility in rid nd semirid soils. The sum of cptured mmonium nd nitrte ions in ion exchnge resins is directly proportionl to the vilility of given key nutrient in its own environment. In other words, this is mount proportionl to the quntity which ws relesed (or lost) from the enclosed internl cycles. The size of stndrd devition illustrtes the gret vriility of results which is typicl for field studies of nitrogen trnsformtions. The mmonium ions re less moile in the soil profile nd they re derived minly from microil trnsformtion of orgnic nitrogen. Therefore the ion exchnge resins pplied into cylindricl holes situted in the upper soil lyer (to depth of 15 cm) hve higher mount of trpped mmonium forms of nitrogen thn nitrte forms (Fig. 3 nd 4). The vilility of soil mmoni-nitrogen in control stockings, nd fter the ddition of rw silk ws not sttisticlly different etween studied yers. Significnt differences were detected only within control mg NH 4 + -N.10 ml IER -1 2,0 1,5 1,0 0,5 rw silk cellulose 0, : The vilility of soil mmoni-nitrogen from the upper soil horizons to depth of 15 cm. Men vlues from 12 replictes (rs) nd SD (lines) re given. Different letters indicte significnt differences (P < 0.05). 2,0 control rw silk cellulose mg N N.10 ml IER -1 1,5 1,0 0,5 0, : The vilility of soil nitrte-nitrogen from the upper soil horizons to depth of 15 cm. Men vlues from 12 replictes (rs) nd SD (lines) re given. Different letters indicte significnt differences (P < 0.05)

4 190 I. Novosádová, J. Záhor, J. D. R. Sinog the vrint with the ddition of cellulose (P < 0.05). Aout the vilility of soil nitrte-nitrogen, the sttisticl differences etween types of IER stockings were found in Only the nitrte-nitrogen cptured y IER with rw silk ws significntly higher in Higher mounts of cptured mmoni form of nitrogen were estimted fter the ddition of rw silk. The mount of cptured mmoni-nitrogen fter ddition of rw silk ws significntly higher in ll yers. It cn e concluded tht the ddition of rw silk supports the relese of mmoni-nitrogen nd restricts the rte of nitrte-nitrogen. However, the ddition of cellulose cn reduce the cpture of nitrte-nitrogen. This iopolymer s sustitute of plnt residues offer the surplus of cron nd energy source for microorgnisms nd thus cuse higher demnds of soil microorgnisms out the sources of soil nitrogen. Binkley (1984) present tht the ddition of cellulose to the soils reduced N vilility in unfertilized nd fertilized soils. Tům et l. (2010) confirm tht the microil competition for ville nitrogen is very high fter the ddition of cellulose, which consequently restrict the rte of minerl nitrogen trpped into the ion exchnge resin. This ws lso evident in our experiment. The only exception occurred in 2009 when the cpture of mmoni-nitrogen ws higher in vrint with cellulose thn in control. It is proly relted to the lowest rinfll, high temperture, low humidity nd high evpotrnspirtion in this yer. Ljth (1988) estlished tht the wet seson vlues of cptured mmoni-nitrogen re significntly greter thn dry seson vlues. Only ccumultion during the wet seson showed significnt differences mong sites, thus stressing the role of field wter regime in interpreting resin ccumultion results. Jingming et l. (1997) confirm the significntly sesonl vrition in pine forest of Dinghushn, with the highest in spring nd the lowest in summer. Sttisticlly significnt differences were found out in content of nitrte-nitrogen cptured y the different types of IER stockings. However, only in 2009, there were no significnt differences in content of nitrtenitrogen cptured y types of IER stockings (Fig. 4) mg N-X.m NH4 NO3 5: The movement of soil minerl nitrogen in the form of mmoni- nd nitrte-nitrogen from the upper soil horizons to depth of 30 cm. Men vlues from 30 replictes (rs) nd SD (lines) re given. Different letters indicte significnt differences (P < 0.05). 90 NO3 80 NH mg N.m : The movement of soil minerl nitrogen in the form of mmoni- nd nitrte-nitrogen from the upper soil horizons to depth of 30 cm

5 The vilility of minerl nitrogen in Mediterrnen open steppe dominted y Stip tencissim L. 191 Most of the cptured nitrte ions into the ion exchnge resins come proly from leching percoltes. This confirms the higher detection of nitrte-nitrogen in ion exchnge resins from the second type of specil cover (discs) inserted into the soil in depth of 30 cm (Fig. 5 nd 6). High levels of totl minerl nitrogen cptured y ion exchnge resin discs were found in The portion of nitrte-nitrogen ws 84% of the totl content of minerl nitrogen. Low mounts of mmoni-nitrogen indicted low vilility of mmoni-nitrogen nd proly high nitrogen use efficiency y the soil iot nd consequently low nitrte movement into the deeper soil horizons. The cpture of soil mmoni-nitrogen ws not sttisticlly different etween ll studied yers. High levels of nitrte-nitrogen cptured y ion exchnge resin discs were found in There were sttisticlly significnt differences etween ll studied yers. The low detection of nitrte nitrogen in 2008 is proly relted to the lowest rinfll. CONCLUSIONS This experiment demonstrted the effect of ddition of redily ville cron nd nitrogen in the form of cellulose or rw silk on vilility of minerl nitrogen directly in soil environment. It cn e concluded tht the ddition of rw silk supports the relese of mmoni-nitrogen nd restricts the rte of nitrte-nitrogen. The ddition of cellulose cn reduce the cpture of nitrte-nitrogen. The higher detection of nitrte-nitrogen in ion exchnge resins inserted into the soil in depth of 30 cm confirms, tht the nitrte ions re more moile in the soil profile. SUMMARY This experiment demonstrted the effect of ddition of cron in the form of cellulose or cron nd nitrogen in the form of rw silk nd zero ddition (control vrint) on vilility of minerl nitrogen directly in soil environment. Mesurements of N vilility nd movement of percolted nitrogen under field conditions include the trpping of minerl N into the ion exchnge resin (IER) inserted into two different types of specil cover (Binkley t Mtson, 1982). Asored NH 4+ -N nd NO 3 -N were evluted y distilltion nd titrtion method (Peoples et l., 1989). The sensitivity of the resin g method to ion moility nd trnsport my e useful for ssessing N vilility to plnt roots, ecuse the driving forces which ffected the cptured mount into the resin gs re nerly the sme s in the cse of nutrient uptke y roots. The sum of cptured mmonium nd nitrte ions in ion exchnge resins is directly proportionl to the vilility of given key nutrient in its own environment. The mmonium ions re less moile in the soil profile nd they re derived minly from microil trnsformtion of orgnic nitrogen. Therefore the ion exchnge resins holes situted in the upper soil lyer (to depth of 15 cm) hve higher mount of trpped mmonium forms of nitrogen thn nitrte forms. On the other hnd, most of the cptured nitrte ions into the ion exchnge resins come from leking percoltes. This confirms the higher detection of nitrte-nitrogen in ion exchnge resins from the second type of specil cover (discs) inserted into the soil in depth of 30 cm. The ddition of rw silk supports the relese of mmoni-nitrogen nd restricts the rte of nitrtenitrogen. However, the microil competition for ville nitrogen is very high fter the ddition of cellulose, which consequently restricts the rte of minerl nitrogen trpped into the ion exchnge resin. This iopolymer s sustitute of plnt residues offer the surplus of cron nd energy source for microorgnisms nd thus cuse higher demnds of soil microorgnisms out the sources of soil nitrogen. Acknowledgements This study ws supported y the Reserch pln No. MSM finnced y the Ministry of Eduction, Youth nd Sports of the Czech Repulic nd y the Reserch pln No. QH72039 finnced y the Ministry of Agriculture of the Czech Repulic. REFERENCES BINKLEY, D., 1984: Ion exchnge resin gs: fctor ffecting estimtes of nitrogen vilility. Soil Science Society of Americ Journl, 48, p , ISSN BINKLEY, D., MATSON, P., 1983: Ion exchnge resin g method for ssessing forest soil nitrogen vilility. Soil Science Society of Americ Journl, 47, p , ISSN FROUZ, J., NOVÁKOVÁ, A., 2005: Development of soil microil properties in topsoil lyer during spontneous succession in heps fter rown col mining in reltion to humus microstructure development. Geoderm, 129, p , ISSN JIANMING, M., MENGDE, Y., GUOHUI, K., 1997: The dynmics of soil NH 4+ - N nd NO 3 -N in pine forest of Dinghushn, s ssessed y ion exchnge

6 192 I. Novosádová, J. Záhor, J. D. R. Sinog resin g method. Act Phytoecologic Sinic, 21(4), p , ISSN X. KAUR, B., GUPTA, S. R., SINGH, G., 2000: Soil cron, microil ctivity nd nitrogen vilility in groforestry system on modertely lkline soils in northern Indi. Applied Soil Ecology, 15, p ISSN LAJTHA, K., 1988: The use of ion-exchnge resin gs for mesuring nutrient vilility in n rid ecosystem. Plnt nd Soil, 105, p , ISSN X. MAESTRE, F., CORTINA, J., 2006: Ecosystem structure nd soil-surfce conditions drive the vriility in the folir 13 C nd 15 N of Stip tencissim in semirid Mediterrnen steppes. Ecologycl Reserch, 21, p , ISSN PEOPLES, M. B., FAIZAH, A. W., RERKASEN, B., HERRIDGE, D. F., 1989: Methods for evluting nitrogen fixtion y nodulted legumes in the field. Acir Monogrph, 11, p. 76, ISSN X RUTIGLIANO, F. A., CASTALDI, S., ASCOLI, R. D., PAPA, S., CARFORA, A., MARZAIOLI, R., FIORETTO, A., 2009: Soil ctivities relted to nitrogen cycle under three plnt cover types in Mediterrnen environment. Applied Soil Ekology, 43, p , ISSN TUMA, I., HOLUB, P., ZÁHORA, J., FIALA, K., 2010: Effect of enhnced nitrogen input on relese of nutrients nd nutrient vilility in stnd of tll fern Athyrium distentifolium. Geophysicl Reserch Astrct [online], Vol. 12, April [cit. EGU ]. Dostupný z www: <http: geophysiclreserch-strcts.net/gr_volume_12.pdf>. ISSN Address Ing. Iren Novosádová, Zemědělský výzkum, spol. s r. o. Trousko, Zhrdní 1, Trousko, Česká repulik, Ing. Jroslv Záhor, CSc., Ústv grochemie, půdoznlství, mikroiologie výživy rostlin, Mendelov univerzit v Brně, Zemědělská 1, Brno , Česká repulik, José Dmin Ruiz-Sinog, Deprtment of Physicl Geogrphy, University of Mlg, Cmpus de Tetinos, Málg 29071, Spin, e-mil: novosdov@vupt.cz, zhor@mendelu.cz, Sinog@um.es