Carbon and Nitrogen Content and Stock in No-Tillage and Crop-livestock Integration Systems in the Cerrado of Goias State, Brazil

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1 Journl of Agriculturl Science; Vol. 4, No. 8; 2012 ISSN E-ISSN Pulished y Cndin Center of Science nd Eduction Cron nd Nitrogen Content nd Stock in No-Tillge nd Crop-livestock Integrtion Systems in the Cerrdo of Gois Stte, Brzil Arcângelo Loss 1, Mrcos Gervsio Pereir 2, Adrino Perin 3 & Lúci Helen Cunh dos Anjos 2 1 Adjunct Professor, Deprtment of Rurl Engineering, Universidde Federl de Snt Ctrin (UFSC), Florinópolis, SC , Brzil 2 Associte Professor III, Deprtment of Soils, UFRRJ, Seropédic, RJ , Brzil. (Sponsored y CNPq) 3 Professor D3I t the Instituto Federl Goino, Rio Verde, GO , Brzil Correspondence: Arcângelo Loss, Adjunct Professor, Deprtment of Rurl Engineering, Center of Agriculturl Sciences, UFSC, Florinópolis, SC , Brzil. Tel: E-mil: rcngeloloss@yhoo.com.r Received: April 11, 2012 Accepted: My 2, 2012 Online Pulished: July 11, 2012 doi: /js.v4n8p96 URL: Prt of the PhD thesis of A. Loss in Soil Science, Postgrdute Course in Agronomy, CPGA-CS, t the Universidde Federl Rurl do Rio de Jneiro (UFRRJ), Seropédic, RJ, , Brzil Astrct The ojective of this study ws to evlute the totl orgnic cron (TOC) nd nitrogen content, nd quntify the TOC nd nitrogen stocks in lnd use systems in the Cerrdo region of Goiás Stte, Brzil. A crop-livestock integrtion system (CLIS) ws evluted - (corn+rchiri/ens/cotton/soy ens) nd no-tillge system (NTS) - (sunflower/millet/soy ens/corn). The vegetl coverge of the nturl Cerrdo, djcent to the NTS nd CLIS, ws considered s the originl soil condition. Soil smples were collected t lyer depths of cm, cm, cm, cm, cm, cm, cm, nd cm, in full rndom experimentl design. The CLIS hd higher contents of TOC nd N thn the NTS up to level of 30.0 cm. Higher nitrogen stocks were oserved in the Cerrdo. In the CLIS, higher TOC contents were found up to 30.0 cm nd nitrogen contents up to 20.0 cm. The sum of stocks up to depth of 100 cm for TOC nd 40 cm for nitrogen ws greter in the CLIS when compred to the NTS. Under the CLIS, the stocks of TOC ( cm) nd nitrogen ( cm) incresed in reltion to those of the NTS. The CLIS ws more efficient in stock ccumultion thn the Cerrdo for the sum of lyers cm nd cm. Keywords: Oxisol, C/N rtio equilirium, root system, crop rottion, moderte use psture 1. Introduction The conversion of crops from no-tillge system (NTS) into crop-livestock integrtion system (CLIS) my result in significnt increses in the soil nutrient content, minly ecuse the integrted system my led to higher soil orgnic mtter content (SOM). In contrst, more intense cultivtion of the soil my result in higher extrction of nutrients from CLIS res. Conclusive studies on the chnges in the distriution of cron nd nitrogen contents nd stocks fter the implementtion of CLIS system re scrce (Mrchão et l., 2009; Crvlho et l., 2010; Loss et l., 2011; Anghinoni et l., 2011). The CLIS hs gret potentil for griculturl use due to the introduction of forge species. In generl, forge species ccumulte more cron thn crops for humn consumption, s the phytomss of the ltter is often insufficient for the mintennce of the soil cover (Mcedo, 2009; Crvlho et l., 2010). The CLIS hs een used s mens of recovering pstures degrded y overgrzing nd low fertility, resulting in improved productivity due to intensified soil use nd minimiztion of ntive vegettion removl (Lnders, 2007; Slton et l., 2008; Gimenez et l., 2009; Ferreir et l., 2011), prticulrly in the Cerrdo morphoclimtic domin. Becuse of the climte, the rte of vegetle residue decomposition in the Cerrdo is very high, quickly leving the soil uncovered. These fctors rpidly led to reduction in the mulch, nd lter to less efficient NTS, when compred to the decomposition rte of other morphoclimtic domins such s the Arucri nd Pmps domins 96

2 Journl of Agriculturl Science Vol. 4, No. 8; 2012 in southern Brzil. The CLIS ecomes fundmentl, s its use in ssocition with the pocee species (rchiri nd perl millet) intensifies the production of mulch, especilly in the dry seson. Besides mulch production, other enefits re etter use of the soil due to the chrcteristics of the grmincee root system, nd ltertions of the cron nd nitrogen cycles in the soil profile (Loss et l., 2011). The introduction of crops ssocited with pstures in the NTS (especilly rchiri), my result in etter environmentl conditions (due the diversity of this system), such s the flow of nutrients, nd other common nturl processes tht led to more conservtionist griculture (Crvlho et l., 2010,; Ferreir et l., 2011; Anghinoni et l., 2011). The NTS contriutes to the increse of cron nd nitrogen stocks in the soil profile, especilly when ssocited with nnul crop rottion (Silv et l., 2009; Mrtins et l., 2009; Boddey et l., 2010). The ssocition of CLIS with n NTS my result in n even greter ccumultion of cron nd nitrogen in the soil profile in comprison with systems not using forge like rchiri (Souz et l., 2009). However, it is still necessry to otin gret volume of dt on this ccumultion pttern for etter guidelines on its use in soil mngement, prticulrly with soy en nd off-seson corn crops in the center-west region of Brzil (Mrtins et l., 2009; Crvlho et l., 2009). Therefore, this study s hypothesis is tht the use of the NTS with modertely intense grzing increses the cron nd nitrogen stocks in soil in reltion to the NTS lone. This study imed to evlute the totl orgnic cron (TOC) nd nitrogen contents nd quntify the TOC nd nitrogen stocks in lnd use systems in the Cerrdo region of Goiás Stte, Brzil. 2. Mteril nd Methods The study ws conducted on the Vrgem Grnde Frm of Agropecuári Peeters, locted in Montividiu, Goiás Stte, Brzil (17 21 S nd W). The re hs well-defined dry seson (from My to Septemer) nd riny seson (from Octoer to April). Annul rinfll is 1500 mm nd the mximum nd minimum tempertures re 30.1 nd 17.8 ºC, respectively. The soil in the systems evluted ws clssified s Oxisol (Soil Survey Stff, 2006) with clyey texture (Ltossolo Vermelho Distrófico; (Emrp, 2006)). In the minerlogicl composition of the cly frction, gisite, kolinite nd hemtite stnd out. The originl vegetl coverge of the soil ws closed cnopy Cerrdo forest, removed in 1975 to estlish pstures (Urochlo decumens) nd then continuously used for 10 yers until 1985 (Figure 1). Soil smpling Cerrdo Psture CTS-grins NTS CLIS Figure 1. Lnd use history with implementtion dtes t the Vrgem Grnde Frm, of Peeters Agriculture nd Livestock, locted in Montividiu, Goiás Stte, Brzil (CTS = conventionl tillge system, NTS = no-tillge system, CLIS = crop-livestock integrtion system The res were then plowed nd hrrowed (CTS) until 1991 (7 yers) for the cultivtion of grins (corn, ens, soy ens nd sunflowers). The NTS ws implemented with crop rottion-corn, soy ens, cotton, ens ( ) nd, from 1999 prt of the NTS ws trnsformed into CLIS ( ). Therefore, the res evluted used n NTS with the sme crop rottion-nts only from nd CLIS from (Figure 1). The res evluted were cultivted using n NTS for 17 yers: one with crop rottion only (sunflower-millet-soyen-corn), t coordintes S, W nd ltitude of 958 m; nd nother with rchiri (U. ruziziensis) intercropped with corn to increse the fodder production in the dry seson (corn-rchiri-ens-cotton-soy ens), t coordintes S, 'W nd ltitude of 859 m. The vegetl coverge of nturl Cerrdo, djcent to the cultivted systems ( 'S, ' W, ltitude of 951 m) ws considered s the originl soil condition. 97

3 Journl of Agriculturl Science Vol. 4, No. 8; 2012 In the CLIS (corn-rchiri-ens-cotton-soy ens), corn nd rchiri were plnted simultneously (rchiri etween corn rows). After the corn hrvest, cttle were introduced to the system t 2.0 AU per h (AU-niml unit) for 90 dys (July-Septemer). After removl of the cttle, only rchiri clumps remined. Then, fter the first rins, the rchiri ws fertilized with 200 kg h -1 of N P K formultion ( ) in the first hlf of Septemer. After regrowth, when the soil ws completely covered y grss, desicction ws done nd ens were grown. Liming ws done in the CLIS in July 2005 using dose of 3.60 Mg h -1 of dolomitic limestone, with Totl Neutrlizing Power (TNP) of 70%, to rise the se sturtion to 70%. The sme procedure ws performed for the NTS, lso in July 2005, using dose of 2.90 Mg h -1 of dolomitic limestone with TNP of 70%, to rise the se sturtion to 60%. The sequence of crops nd fertilizers used in oth systems from 2002 to 2008 is descried in Tle 1. Tle 1. Fertiliztion nd cropping sequences used in the evluted systems of the Vrgem Grnde Frm of Peeters Agriculture nd Livestock, locted in Montividiu, Goiás Stte, Brzil Yer Month Culture Fertilizer Crop Coverge CLIS (corn-rchiri-en-cotton-soyen) 2002 Octoer Soy ens 580 kg h -1 of Ferury Corn + rchiri 500 kg h -1 of kg h -1 of ure 2003 Octoer Soy ens 580 kg h -1 of Ferury Corn + rchiri 450 kg h -1 of kg h -1 of ure 2004 Octoer Soyens 500 kg h -1 of Ferury Corn + rchiri 490 kg h -1 of kg h -1 of ure 2005 Septemer Bens 400 kg h -1 of kg h -1 of ure 2005 Decemer Cotton 500 kg h -1 of kg h -1 of Octoer Soy ens 500 kg h -1 of Ferury Corn + rchiri 450 kg h -1 of kg h -1 of ure 2007 Octoer Soy ens 450 kg h -1 of Ferury Corn + rchiri 450 kg h -1 of kg h -1 of ure 2008 Septemer Bens 400 kg h -1 of kg h -1 of ure 2008 Decemer Cotton 500 kg h -1 of kg h -1 of NTS 1 (sunflower/millet/soy ens/corn) 2002 August Millet Octoer Soy ens 550 kg h -1 of Ferury Corn 450 kg h -1 of kg h -1 of ure 2003 August Millet Octoer Soy ens 550 kg h -1 of Ferury Corn 450 kg h -1 of kg h -1 of ure 2004 August Millet Octoer Soy ens 550 kg h -1 of Ferury Corn 450 kg h -1 of kg h -1 of ure 2005 August Millet Octoer Soy ens 550 kg h -1 of Ferury Sunflower 300 kg h -1 of kg h -1 of ure 2006 August Millet Octoer Soy ens 500 kg h -1 of Ferury Corn 400 kg h -1 of kg h -1 of ure 2007 August Millet Octoer Soy ens 500 kg h -1 of Ferury Sunflower 300 kg h -1 of kg h -1 of ure 2008 August Millet Octoer Soyen 500 kg h -1 of For the NTS, in August of ech yer ( ) millet ws plnted for fodder production nd soy ens were plnted in Octoer. Before 2002, off-seson nd millet crops were not plnted nd the system remined t rest during My to Septemer, during which plnts of the grss fmily such s guine grss nd rchiri grew spontneously. NTS = no-tillge system, CLIS = crop-livestock integrtion system. 98

4 Journl of Agriculturl Science Vol. 4, No. 8; 2012 For soil smpling in Mrch 2008, the NTS ws cropped with sunflowers nd the CLIS with corn nd rchiri. A 600 m 2 section ws mrked in ech system nd four trenches were opened crosswise to crop rows for soil smpling t depths of cm, cm, cm, cm, cm, cm, cm nd cm. Three single smples in ech trench were collected to form composite smple, totling four replictions in ech lnd use system. After collection, the smples were ir-dried nd sieved with 2 mm mesh sieve to otin ir-dried ground soil (ADGS). At the sme depths, soil smples were collected to determine ulk density, using the volumetric ring method (Emrp, 1997). The vlues otined were used to clculte the equivlent soil mss nd nlyze cron nd nitrogen stocks in the soil profile. The TOC nd totl nitrogen contents were determined y the dry comustion method in n AutoAnlyzer t 900 C (CHN-600 Crlo Er EA-1110, Itly). TOC nd nitrogen stocks were clculted using the equivlent soil mss method (Ellert & Bettny, 1995; Sisti et l., 2004), s descried elow: where: C S = totl stock (Mg h -1 ); C C M M M C n 1 n n S Ti Tn Ti Si Tn i 1 i 1 i 1, n 1 i 1 C Ti = sum of nutrients from the most superficil to the deepest lyer of the soil profile evluted in specific experimentl re (Mg h -1 ); n M Ti = sum of soil mss from the most superficil to the deepest lyer of the soil profile investigted in i 1 specific experimentl re (Mg h -1 ); n M Si = sum of soil mss from the most superficil to the deepest lyer of the soil profile smpled s i 1 reference tretment (Mg h -1 ); M Tn = soil mss in the deepest lyer of the soil profile ssessed in specific experimentl re (Mg h -1 ); C Tn = nutrient level t the deepest lyer of the soil profile studied in specific experimentl re (Mg nutrient. Mg soil -1 ). The results were nlyzed for dt normlity nd homogeneity y mens of the Lilliefors nd Cochrn nd Brtlett tests. Lter, completely rndomized design with three lnd use systems (NTS, CLIS nd Cerrdo) nd four replictions, ws nlyzed. The lnd use systems were evluted under the sme climtic nd topogrphic soil conditions. The results were sumitted to vrince nlysis with ppliction of the F test. The men vlues, when significnt, were compred with n LSD-student test, t 5% proility. 3. Results nd Discussion 3.1 Distriution of TOC nd Nitrogen Contents in the Soil Profile In the Cerrdo, NTS, nd CLIS, the TOC nd totl nitrogen contents decresed proportionlly to the increse in the depth of the soil smple (Figures 2 nd 3). This pttern results from the greter input of vegetle residues on the top lyer of the soil from rotted crops in the crop systems nd from litter in the Cerrdo. With greter deposition of vegetle mteril, the TOC nd nitrogen contents were higher in the surfce lyers (prticulrly in the cm lyer) in comprison to the deeper lyers. These results re similr to those reported y Jntli et l. (2007); Siqueir et l. (2009) nd Cost Junior et l. (2011 & 2011) for the TOC nd nitrogen dynmics in the soil-plnt-tmosphere system with different soil use systems in the Cerrdo. 99

5 Journl of Agriculturl Science Vol. 4, No. 8; 2012 Depth (cm) ,0 11,0 14,0 17,0 20,0 23,0 26,0 29,0 32,0 35,0 38,0 41,0 44,0 Totl orgnic cron ( g kg -1 ) ns ns c CLIS Cerrdo NTS Figure 2. Totl orgnic cron in soil for lnd use systems in Montividiu, Goiás Stte, Brzil. (The error rs indicte the stndrd error of the men vlues for four repetitions). Men vlues followed y the sme letter do not differ mong the systems ssessed for ech depth, ccording to the LSD-student test t 5%. ns = not significnt in the F test 5%. NTS = no-tillge system; CLIS = crop-livestock integrtion system Depth (cm) ns Totl soil nitrogen ( g kg -1 ) 0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 ns c CLIS Cerrdo NTS Figure 3. Totl soil nitrogen for different lnd use systems in Montividiu, Goiás Stte, Brzil. (The error rs indicte the stndrd error of the men vlues for four repetitions). Men vlues followed y the sme letter do not differ mong the systems ssessed for ech depth, ccording to the LSD-student test t 5%. ns = not significnt y the F test 5%. NTS = no-tillge system; CLIS = crop-livestock integrtion system The highest TOC nd nitrogen contents were found in the Cerrdo, followed y the CLIS nd the NTS, in the cm lyer. The TOC vlues were 40.54, nd g kg -1, in the Cerrdo, CLIS nd the NTS, respectively (Figure 2). The nitrogen contents were 3.18, 1.85, nd 1.65 g kg -1, in the Cerrdo, CLIS, nd NTS, respectively (Figure 3). The high TOC ( cm lyer) nd nitrogen contents in the Cerrdo result from the constnt litter deposition in this re nd the greter chemicl nd physicl stility of this system, the originl soil condition. The lef litter deposited in the Cerrdo is the most expressive comprtment of cron nd nitrogen input when compred with the other soil use systems. For lyer depths etween cm nd cm, the CLIS hd higher TOC contents with no differences etween the vlues of the NTS nd Cerrdo. Lyers cm, cm, nd cm did not present differences in the systems ssessed nd the lyers elow 60.0 cm in the Cerrdo hd the gretest TOC contents, with no difference etween the NTS nd the CLIS (Figure 2). Among the crop systems, greter TOC ( cm) nd nitrogen ( cm) contents were oserved in the CLIS, reltive to the NTS. This my e ttriuted to the use of rchiri together with off-seson corn which 100

6 Journl of Agriculturl Science Vol. 4, No. 8; 2012 produces greter mount of strw, nd, therefore, fvors the ccumultion of cron nd nitrogen due to the soil exploittion y the root system. The use of two leguminose (soy ens nd ens) in the CLIS nd only soy ens in the NTS is nother fctor (Tle 1). It is importnt to point out tht increses in the nitrogen content, y either iologicl fixtion (leguminose) or nitrogen fertiliztion, fvor the ccumultion of cron in the soil (Byer & Mielniczuk, 1997; Urquig et l., 2005). According to Pillon et l. (2004), the incorportion of vegetle mteril through the roots t greter depths of the soil profile is n importnt strtegy for improving the qulity of the surfce soil nd for the ccumultion of cron in the soil. Nitrogen certinly exerts key role in cron ccumultion, s the TOC does not increse when the nitrogen content is limiting fctor of the iologicl ctivity (Urquig et l., 2005). This close reltionship etween the cron nd nitrogen contents ws oserved in different loctions in Brzil for grin crops, Cerrdo, nd ntive forest conditions, in soil lyers up to 100 cm deep (Sisti et l., 2004). This corroortes the results found in this study. At the other depths ( cm, cm nd cm), the similrity etween the TOC contents (sence of differences etween the systems) indictes tht the crops grown in the NTS nd the CLIS for 17 yers hd the sme TOC contents s the originl system (Cerrdo). However, in lyers cm nd cm, the crop systems hd not recovered the originl Cerrdo contents their TOC vlues were lower thn those of the Cerrdo. The nitrogen content of the Cerrdo ws higher in ll lyers, with the exception of lyers cm nd cm, which did not differ from ech other. Among the crop systems, the CLIS hd the gretest vlues only in the cm lyer, with no differences for the other studied lyers up to cm (Figure 3). The nitrogen vlues in the CLIS rnged from 1.85 to 0.54 g kg -1, while in the NTS the contents rnged from 1.65 to 0.60 g kg -1. The differences found in the nitrogen contents of the surfce soil lyer in the crop systems re relted to the minerl fertiliztion used nd the use of two leguminose (soy ens nd ens) in the CLIS nd soy ens only in the NTS (Tle 1). 3.2 Distriution of Cron nd Nitrogen Stocks in the Soil Profile The gretest TOC stocks were found in lyers cm, cm nd cm in the Cerrdo (Tle 2). This pttern for the cm lyer is relted to the lrge deposition of orgnic mtter, which is greter in this re due to the input of vegetle residues (litter) nd the sence of nthropic influence. The greter stocks of TOC t deep lyers indicte tht the originl TOC contents of the soil hve still not recovered fter the removl of the Cerrdo for the implementtion of the NTS. Tle 2. Totl orgnic cron stocks (Mg h -1 ) in soil for lnd use systems in Montividiu, Goiás Stte, Brzil Soil use systems Soil Lyers (cm) Cerrdo c ns CLIS ns NTS c ns Sum of Soil Lyer Vlues (cm) Cerrdo CLIS NTS c c c Mens followed y the sme letter in the columns do not differ mong systems ssessed y the LSD-Student test t 5%. ns = not significnt y the F test 5%. NTS = no-tillge system; CLIS = crop-livestock integrtion system Among the crop systems, the gretest TOC stocks were found in the cm, cm nd cm lyers of the CLIS. No difference ws oserved etween the systems in lyers cm, cm nd cm. The other lyers did not differ etween crop systems (Tle 2). The nitrogen stocks hd greter vlues in ll lyers of the Cerrdo studied. In the cultivted systems, the gretest nitrogen stocks were found in lyers cm nd cm, with no differences etween lyers cm, cm nd cm. In the other lyers ( cm, cm nd cm), the NTS hd the gretest nitrogen stocks (Tle 3). 101

7 Journl of Agriculturl Science Vol. 4, No. 8; 2012 Tle 3. Totl nitrogen stocks (Mg h -1 ) in soil for lnd use systems in Montividiu, Goiás Stte, Brzil Soil use systems Soil Lyers (cm) Cerrdo CLIS c 0.73 c 1.48 c 1.33 NTS 1.47 c 1.29 c Sum of Soil Lyer Vlues (cm) Cerrdo CLIS NTS 2.76 c 5.17c Men vlues followed y the sme letter in the columns do not differ mong the systems ssessed y the LSD-Student test t 5%. ns = not significnt y the F test 5%. NTS = no-tillge system; CLIS = Crop-livestock integrtion system. The gretest TOC nd nitrogen stocks in the CLIS my e ttriuted to the use of rchiri which provides slower degrding crop residues, nd, therefore, fvors the ccumultion of cron due to its greter C/N rtio, in ddition to the effect under the surfce of the root system s expnsion nd renewl, which dds cron nd nitrogen to the soil profile. These cron nd nitrogen contents re physiclly protected inside ggregtes tht re highly stle in wter due to iron nd luminum oxides (Byer et l., 2000) which form highly stle ggregtes (Loss et l., 2011) with cron nd nitrogen occluded on the inside (Bere et l., 1994; Roscoe et l., 2001). The use of rchiri to intensify the production of strw in the dry seson, ssocited with grzing of 2 nimls/h, proly led to etter mss rtio etween the roots nd the exposed prts in the CLIS, in comprison to the NTS, nd, in turn, to n increse in the TOC nd nitrogen contents. These results corroorte those found y Dieckow et l. (2005) for TOC nd nitrogen stocks in NTS for period of 17 yers in southern Brzil. The eneficil effect of the CLIS with dequte grzing intensity, results from the etter mss rtio etween the roots nd exposed prts, which ccumultes over time due to the miniml gittion of the soil, nd, therefore, little mechnicl incorportion of vegetle residues nd reduced oxidtion. Thus, cron nd nitrogen ccumulte on the surfce nd t depth, the increse in the cron nd nitrogen stocks in the CLIS eing relted to the trnsporttion of vegetle residues from the surfce of the soil y the mcro nd mesofun which re greter in integrted systems in reltion to single systems (Anghinoni et l., 2011). The NTS res hve een cultivted for n verge of 17 yers nd re considered to e in the phse of soil system evolution, with the NTS cultivtion time s the consolidtion phse (10 to 20 yers of NTS use) ccording to (Anghinoni, 2007). In this phse, strw nd SOM ccumulte, the ction-exchnge cpcity of the soil increses, more wter is stored, nd nutrients re recycled. The CLIS hd higher vlues of TOC nd nitrogen thn the NTS in the surfce lyers (up to 30.0 cm for TOC nd 20.0 cm for nitrogen) s well s for the sum of the lyers (up to 100 cm for TOC nd 40.0 cm for nitrogen). This result indictes the efficient ccumultion of TOC nd nitrogen stocks in the CLIS which is more efficient thn crop rottion with rchiri sent. In cultivted systems, the sence of soil gittion, crop rottion nd the permnence of crop residues on the soil surfce, fvors ggregtion nd ffords greter protection to the orgnic mtter (Slton et l., 2008), nd, consequently, n increse in the TOC nd nitrogen stocks. For nitrogen stocks, only the cm, cm nd cm lyers in the NTS hd greter stocks thn the CLIS. The crop systems produce nnul crops nd one off-seson crop, while off-seson crops in the NTS hve een used only in the lst five yers. Before tht, fter the corn crop, the system ws left to rest nd tken over y invding crops such s guine grss nd rchiri. Perl millet lso hs n effect, s it is sown in August so tht soy ens cn e sown in Octoer (Tle 1). The deth of the roots of these grmincee tht hve deep root systems, dds nitrogen to the soil, resulting in greter nitrogen stocks in the NTS lyers mentioned ove in comprison to the CLIS. The TOC nd nitrogen stock vlues found in lyers cm (94.95 nd Mg h -1 for TOC, nd 5.48 nd 5.17 Mg h -1 for nitrogen) for CLIS nd NTS, respectively; nd in the cm lyer ( nd Mg h -1 for TOC, nd 9.92 nd Mg h -1 ) for CLIS nd NTS, respectively; re greter thn those found y Jntli et l. (2007), with the exception of the TOC stock in the NTS t cm. The uthors evluted the dynmics 102

8 Journl of Agriculturl Science Vol. 4, No. 8; 2012 of the TOC nd nitrogen stocks in n Oxisol (Ltossolo Vermelho) in Plnltin in Brzil s Federl District (lso in Cerrdo nd NTS environment), with the following crop rottions: corn, soy ens, perl millet (NTS1) nd the sme previous rottion, ut ssocited with Andropogon gynus grss (NTS2). The TOC stock vlues found y Jntli et l. (2007) were 84 Mg h -1 for NTS1 nd NTS2 t cm depth, nd 139 nd 143 Mg h -1 for NTS1 nd NTS2 t cm depth. For the nitrogen stocks, vlues of 4.9 nd 5.1 Mg h -1 t cm depth, for NTS1 nd NTS2 were found; nd 8.2 nd 8.5 Mg h -1 for NTS1 nd NTS2 t cm depth. The results found followed the pttern oserved y Jntli et l. (2007). The uthors oserved greter TOC nd nitrogen stocks in the NTS with Andropogon gynus grss s cover plnt together with crop rottion, eing similr in the CLIS with rchiri nd off-seson corn. The TOC stock vlues for lyers cm nd cm were compred. The CLIS presented greter TOC stocks thn the Cerrdo, nd in the cm lyer, the opposite pttern ws oserved (Tle 2). These results lso show the importnce of the study of the TOC stocks up to depth of cm, considering tht the lyers must hve regulr thickness intervls (like 10 cm), so tht the effect of the crop systems cn e oserved for the sum of the lyers. In this study, the CLIS hd greter TOC stocks thn the originl soil condition (Cerrdo) t depths up to 60.0 cm. If the study hd presented the sum of the lyers up to cm deep lone ( cm), the effect of the CLIS would hve een wekened t deeper lyers when compred to the Cerrdo. Among the crop systems, the gretest TOC stocks in the CLIS my result from the use of crop rottion. This my hve positive effect in the nitrogen equilirium (soy ens, ens, nd chemicl fertiliztion), which, in turn, is relted to the cron input, llowing the joint incorportion of these elements for the SOM (Sisti et l., 2004; Urguig et l., 2005; Jntli et l., 2007). This pttern ws oserved in the present study, with greter nitrogen stocks in lyers cm nd cm for the CLIS (Tle 3) in ssocition with greter TOC stocks in these lyers (Tle 2). These results indicte tht the content of orgnic nitrogen in soil cnnot e incresed without there eing corresponding increse in the TOC content, nd vice-vers, s reported y Urguig et l. (2005) in study on griculturl systems for cron sequestrtion in tropicl nd sutropicl environments. The ssocition of the CLIS nd NTS with moderte grzing comines the sence of soil rottion nd high vegetle residue input from the use of crops nd pstures (Anghinoni et l., 2011; Loss et l., 2011). This pttern lso supports the greter TOC (0.0 to 30.0 cm, Tle 2) nd nitrogen (0.0 to 20.0 cm, Tle 3) stocks found in the CLIS in reltion to the re with no psture (NTS). After 17 yers of use of the soil with conservtionist system, using only the NTS from 1991 to 1999 nd CLIS from 1999 to 2008 (Figure 1), the TOC stocks hd recovered (resilience), reching the sme vlues in the NTS, CLIS nd Cerrdo, t depths of cm, cm, nd cm, nd greter vlues in the CLIS for depths of cm nd cm (Tle 2). The results oserved in the present study re similr to those from some studies in Brzilin tropicl nd sutropicl conditions with the incresing use of grss mulching for the formtion of soil coverge, resulting in differentited input of crop residues in reltion to pure systems of grin production, oth t the surfce nd in the soil profile (Souz et l., 2009, 2010; Loss et l., 2011). As such, it is possile to conclude tht CLIS mngement over time nd under the no-till system in conditions of moderte grzing (2 nimls per hectre), promotes lower outputs of cron nd nitrogen from microil respirtion (Souz et l., 2010) nd grzing. As consequence, the stocks of these elements in soil tend to e greter, s shown in Tles 2 nd Conclusions The use of the CLIS with corn+rchiri/ens/cotton/soy ens under moderte grzing (2 nimls/h) incresed the stocks of TOC ( cm nd for the sum of the lyers up to depth of cm) nd of nitrogen ( cm nd for the sum of the lyers up to depth of 40.0 cm) when compred to the NTS with sunflower/perl millet/soy ens/corn. The CLIS is more efficient in TOC stock ccumultion thn the Cerrdo for lyers cm nd cm nd for the sum of the lyers cm nd cm. Acknowledgements To the Agrisus Foundtion for funding the reserch project, to CNPq nd FAPERJ for grnting the PhD scholrship to the first uthor, to the Post-grdution Progrm in Agronomy - Soil Science (CPGA-CS) for their ssistnce nd to Dr. Adrino Perin nd collegues for their help in collecting soil smples for this study. References Anghinoni, I., Mores, A., Crvlho, P. C. F., Souz, E. D., Conte, O., & Lng, C. R. (2011). Benefícios d integrção lvour-pecuári sore fertilidde do solo em sistem plntio direto. In Fonsec, A. F., Cires, 103

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