Chemical and physical fractions of soil organic matter under various management regimes in Roraima, Brazil

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1 DOI: / v38n4Supl1p2419 Chemicl nd physicl frctions of soil orgnic mtter under vrious mngement regimes in Rorim, Brzil Frções químics e físics d mtéri orgânic do solo sob diferentes sistems de uso em Rorim Mrden Dniel Espinoz Gurdiol 1 ; José Frutuoso do Vle Júnior 2 ; Edmilson Evngelist d Silv 3 ; Celeste Queiroz Rossi 4 ; Mrcos Gervsio Pereir 5* Abstrct The crop-livestock integrtion (CLI) nd crop-livestock-forest integrtion (CLFI) mngement systems, hve been shown to be vible pproches for incresing crbon sequestrtion in soils, resulting in the improvement of physicl nd chemicl soil ttributes. The objective of this study ws to evlute the chemicl ttributes nd orgnic mtter in soils under Nturl Forest (NF) converted to different uses nd mnged differently: rottionl psture re (PAST), crop-livestock integrtion (CLI), nd croplivestock-forest integrtion (CLIF). The reserch ws conducted t the São Pulo frm, in Ircem, locted in the south-centrl region of the stte of Rorim, Brzil. The studied soil type ws clssified s Ultisol. Soil smples were tken by opening ditches nd exmining lyers t 0.1-m depth intervls from surfce to 0.60-m depth. Totl orgnic crbon (TOC), chemicl nd grnulometric frctiontion of soil orgnic mtter (SOM), oxidizble frctions, nd light orgnic mtter in wter were nlyzed. Our results showed low levels of the nlyzed chemicl elements, chrcteristic of soil with low nturl fertility. This mtches conditions inherent in source mteril, wethered by high rinfll, wrm nd humid climte, nd flt topogrphic relief. In the m lyer, the PAST nd CLI systems hd the highest TOC contents reltive to the other systems studied. At other depths, there were no sttisticl differences mong TOC levels. The highest concentrtion of C in the prticulte frction (POC) ws noted in the surfce lyer in ll mngement systems. The psture system hd the highest concentrtion POC in the top 0.10 m. Our results lso showed tht the upper 0.10 m of soil in NF contined the lowest content of orgnic crbon ssocited with minerl (MOC) reltive to the mnged grosystems. In ddition, humin provided the lrgest contribution to SOM in ll evluted mngement systems. The crop-livestock integrtion (CLI) nd crop-livestock integrtion forest (CLIF) systems, emerged s strong lterntive to crbon incorportion nd subsequently the improvement of physicl nd chemicl soil ttributes. The objective of this work to evlute the chemicl ttributes nd orgnic mtter in soils under Nturl forest (NF) converted into different use nd mngement systems: psture (PAST), croplivestock Integrtion (CLI) nd crop-livestock Integrtion forest (CLIF). The reserch ws conducted t São Pulo frm in Ircem, locted in the Center-South region of the Stte of Rorim, Brzil. The soil studied ws clssified s Argissolo Amrelo Distrófico. The smples were tken by the opening 1 Prof. Auxilir, Centro Universitário Regionl del Litorl Atlántico, CURLA, Universidd Ncionl Autónom de Hondurs, UNAH, L Ceib, Hondurs. E mil: mrden.espinoz@unh.edu.hn 2 Professor Titulr do Centro de Ciêncis Agráris, Universidde Federl de Rorim, UFRR, Bo Vist, RR, Brsil. E mil: vlejr51@gmil.com 3 Pesquisdor, Empres Brsileir de Pesquis Agropecuári, EMBRAPA Rorim, Bo Vist, RR, Brsil. E mil: edmilson.e.silv@ embrp.br 4 Pós-Doutornd, Curso de Pós-Grdução em Agronomi, Ciênci do Solo, CPGA/CS, Universidde Federl Rurl do Rio de Jneiro, UFRRJ, Seropédic, Rio de Jneiro, Brsil. Bolsist Fperj. E mil: celesteqrossi@yhoo.com.br 5 Prof. Titulr, Deprtmento de Solos, UFRRJ, Bolsist do CNPq, Seropédic, RJ, Brsil. E mil: mgervsiopereir01@gmil. com * Author for correspondence Received: Oct. 30, 2016 Approved: Feb. 16,

2 Gurdiol, M. D. E. et l. of trenches in lyers of , , , nd m depth. Totl orgnic crbon (TOC), chemicl nd grnulometric frctiontion of soil orgnic mtter (SOM), oxidizble frctions nd orgnic mtter in wter were nlyzed. The results showed low levels of the nlyzed chemicl elements which chrcterizes soils with low nturl fertility, which mtches the conditions of the source mteril, high rinfll nd regionl temperture, s well s the flt locl relief. In the m lyer, the PAST nd CLI systems hd the highest TOC contents when compred to the other systems studied, in the other depths there were no sttisticl differences between the TOC levels. The highest mount of C in the prticulte frction (COp) ws verified in the surfce lyer in ll evluted mngement systems. The psture re ws the system with the gretest contribution of COp to the depth of m. In reltion to the crbon content ssocited with minerls (COm), the results showed tht the depth of m NF re presented the lowest levels when compred to the other systems. Regrding the humic substnces, there ws lrger contribution of humin in ll evluted systems. Key words: Soil Fertility. Orgnic Crbon Frctiontion. Chrcteriztion of Soil Orgnic Mtter. Resumo Os sistems de integrção lvour-pecuári (ILP) e lvour-pecuári florest (ILPF) surgirm como forte lterntiv pr incorporção de crbono e consequentemente melhori nos tributos físicos e químics do solo. Objetivou-se com o presente trblho vlir os tributos químicos e mtéri orgânic em solos sob Florest Nturl (FN) convertidos em diferentes sistems de uso e mnejo: pstgem (PAST), Integrção lvour-pecuári (ILP) e Integrção lvour-pecuári florest (ILPF). O estudo foi relizdo n fzend São Pulo, em Ircem, loclizd n região centro-sul do estdo de Rorim. O solo estuddo foi clssificdo em Argissolo Amrelo Distrófico. As mostrs form retirds medinte bertur de trincheirs ns cmds de 0-0,10, 0,10-0,20, 0,20-0,40 e 0,40-0,60 m de profundidde. Form nlisdos o crbono orgânico totl (COT), frcionmento químico e grnulométrico d MOS, s frções oxidáveis e mtéri orgânic leve em águ. Os resultdos mostrrm bixos teores dos elementos químicos nlisdos, o que crcteriz solos com bix fertilidde nturl, que condiz com s condições do mteril de origem, elevds precipitções e tempertur regionl, bem como o relevo locl plno. N cmd de 0-0,10 m os sistems PAST e ILP presentrm os miores teores de COT qundo comprdos os outros sistems estuddos, ns demis profundiddes não se verificou diferençs esttístics entre os teores de COT. A mior quntidde de C n frção prticuld (COp) foi verificd n cmd superficil em todos os sistems de mnejo vlidos. A áre de pstgem foi o sistem com mior contribuição do COp n profundidde de 0-0,10 m. Com relção os teores do crbono ssocido os mineris (COm), os resultdos demostrrm que n profundidde de 0-0,10 m, áre de FN presentou os menores teores qundo comprdos os outros sistems. Em relção às substâncis húmics houve um mior contribuição d Humin em todos os sistems vlidos. Plvrs-chve: Fertilidde do solo. Frcionmento do Crbono Orgânico. Crcterizção d Mtéri Orgânic do Solo. Introduction It hs been evident in recent yers tht economic dvncement, griculturl production, nd incresed use of inputs worldwide hve led to incresed deforesttion nd conversion of nturl res to griculturl lnds commercil crops. Mintining soil qulity is one of the key mechnisms for chieving long-term sustinbility of griculturl systems nd emphsizing sustinble lnd mngement is the min pproch for preserving soil orgnic mtter (CAETANO et l., 2013). Soil orgnic mtter (SOM) is one of the most importnt constituents mintining tropicl soil fertility. SOM formtion occurs through the decomposition of plnts nd nimls, during constnt process of trnsformtion nd synthesis. This is key process for the sustinble mintennce of terrestril ecosystems (BENITES et l., 2010). 2420

3 Chemicl nd physicl frctions of soil orgnic mtter under vrious mngement regimes in Rorim, Brzil The types of SOM nd chemicl chrcteristics of soil re directly linked nd chnge ccording to the type of mngement prctices dopted (CARVALHO et l., 2010). In generl, the min obstcles to mintining soil qulity in tropicl soils, especilly for the mjority of Oxisol nd Ultisol, re their low totl ction-exchnge cpcities (CEC), high phosphorus-binding, nd toxic luminum concentrtions (Al 3+ ). However, these drwbcks my be reduced with input nd preservtion of soil orgnic crbon content (BALDOTTO et l., 2015). The use of systems with different inputs of plnt biomss cn be reveled through prticulte frction of SOM, in wy tht it is possible to use it s n indictor to mesure soil qulity, especilly in short period (CONCEIÇÃO et l., 2005; ROSSI et l., 2012). However, it is crucil to identify the different frctions, s well s the forms of protection under nturl vegettion nd vrious gro-mngement systems (FIGUEIREDO et l., 2010). Converting nturl res to griculture, with the resulting reduction of nturl vegettion, cn reduce the content of SOM, cusing loss in soil fertility, nd incresed erosion (BERNOUX et l., 2004). However, the doption of conservtion mngement prctices tht prioritize the input nd mintennce of SOM levels my lso contribute to the sequestrtion of C. Crop-livestock integrtion systems, no-tillge mngement, the use of cover crops nd fllow system, crop rottion, vrious groforestry systems, mong others, re ll exmples of such systems tht contribute to C sequestrtion (FERREIRA et l., 2012; PAUL et l., 2013). Crop-livestock integrtion mngement systems cn be chrcterized by four bsic types: (1) croplivestock integrtion (CLI), or gro-pstorl systems, is production type tht ssocites the griculturl nd livestock components in rottionl, union, or successionl pttern, in the sme re nd in the sme gronomic yer, or over multiple yers; (2) livestock-forest integrtion (LFI), or silvo-pstorl system, is production type tht integrtes livestock (psture nd niml) nd forestry components in consortium; (3) crop-forest integrtion (CFI) or silvo-griculturl system, is production type tht integrtes forest nd griculturl components, in consortium of tree species with griculturl crops (nnul or perennil); nd, (4) crop-livestock-forest integrtion (CLFI), which is production type tht ssocites, in the sme re, griculturl, livestock, nd forestry components in rottionl, consortium, or successionl pttern (BALBINO et l., 2011). Recently, the doption of crop-livestock integrtion (CLI) nd crop-livestock-forest integrtion (CLFI) hve been found to provide better conservtion of soil chemicl nd physicl ttributes in some regions of Brzil (FRAZÃO et l., 2010; SALES et l., 2010). These systems hve been used s tool to restoredegrded res becuse they llow for diversifiction of production (griculturl, livestock, nd forest mngement systems) in the sme re, which in turn improves the physicl, chemicl, nd biologicl chrcteristics of soils, increses nutrient cycling cpcity, reduces crop production costs, increses the income of the producer, decreses the pressure for deforesttion of new res with ntive forests, nd reduces the emission of greenhouse gses; therefore, ll these mngement systems improve the soil crbon cycle. A significnt increse hs been observed in the doption of integrted cropping systems, such s CLI, which hve considerble potentil for soil C ccumultion. According to Kluthcouski nd Oliveir (2012), the use of perennil grsses in CLI, such s brchiris, whether in consortium, succession, or rottion with nnul crops, cn minimize soil degrdtion, due to the beneficil effect of these grsses hve on physicl ttributes of soils. It cn lso increse the soil C stock nd reduce greenhouse gs emissions to the tmosphere. Soil chemicl ttributes nd TOC frctions hve been considered indictors of soil qulity mong res with differing gro-mngement systems (in severl Biomes). Therefore, this study imed 2421

4 Gurdiol, M. D. E. et l. to evlute the chemicl nd physicl frctions of soil orgnic mtter in Argissolo Amrelo Distrófico (Ultisol) soils, mong vrious systems of lnd use nd mngement in the municiplity of Ircem Rorim, Brzil. Mteril nd Methods Our study ws crried out t the São Pulo frm in Ircem, locted in the south-centrl region of the stte of Rorim ( N nd W), in the community of Roxinho, Brzil. The region of the study comprises trnsitionl bioclimtic scenrio in the Amzon. According to the clssifiction of Köppen, the climte of the southern portion is defined s Am (Tropicl Monsoon) nd trnsitions to Aw (Tropicl Wet nd Dry or Svnnh) in the northern portion (BARBOSA, 1997). The studied soils were clssified s Argissolo Amrelo Distrófico (Ultisol), ccording to the Brzilin System of Soil Clssifiction - SiBCS (SANTOS et l., 2013), with texture rnging from medium to clyey (Tble 1). Tble 1. Grnulometric composition of soils under different mngement systems, seven yers fter implementtion, in the Semidecidul Sesonl Forest Region, Rorim, Brzil. Depth Tretments Cly Silt Sndy (m) g kg -1 PAST ,10 NF CLI CLFI PAST ,10-0,20 NF CLI CLFI PAST ,20-0,40 NF CLI CLFI PAST ,40-0,60 NF CLI CLFI PAST (rottionl psture re), NF (nturl forest), CLI (crop-livestock integrtion system), nd CLFI (crop-livestock-forest integrtion system). Our experiment ws conducted in 2009, in n re previously occupied by Nturl Forest (NF). The study re covered totl re of 58 h, which included crop-livestock-forest integrtion mngement system (CLFI) of 15.6 h, croplivestock integrtion system (CLI) of 8.5 h, nd rottionl psture system (PAST) of 33.9 h. The nturl vegettion (NF) is Semidecidul Sesonl Forest nd ws used s control for the other grosystems studied. The preprtion of the CLI nd CLFI res were mde through the plowing nd incorportion of 1500 kg h -1 of dolomitic limestone, 50 kg h -1 of FTE BR 12 nd 90 kg of P 2 O 5 in the form of single superphosphte. In the CLFI mngement system, trees were plnted NE-SW in five rows spced by 70 m, in 2422

5 Chemicl nd physicl frctions of soil orgnic mtter under vrious mngement regimes in Rorim, Brzil vrious rrngements reltive to the plnted species: Cedro espino (Bombcopsis quint), Tek (Tecton grndis), Txi (Sclerolobium pnicultum), nd Gliricidi (Gliricidi sepium). The spcing within the lleys (non-tree res) were 3 x 4 m, but where there were externl lines of Gliricidi (t the edges of the lleys), these trees were spced by 1 m. Urochlo briznth Mrndu ws used s forge, intercropped with rice, mong the lleys nd received 90, 72, nd 90 kg h -1 of N, P 2 O 5, nd K 2 O, respectively. Cowpe bens (plnted in the interrows of trees in 2009) were fertilized with 18 nd 30 kg h -1 of P 2 O 5 nd K 2 O, respectively. In 2010 nd 2011, the soyben crop ws plnted in the no-tillge system between My 10 nd 15. Animls (Cttle) begn grzing in the system on November 15, 2009, remining until April 30 (165 dys). In 2010 the grzing occurred from December 15 to April 6, 2011 (130 dys). After this period, the res of CLFI were fenced in nd no longer cultivted with grins, thus beginning the period of continuous grzing. The entrnce of the nimls occurred on November 15, 2011, nd by this point in time, the nimls hd lredy ccessed the tree lines. In the CLI system, Urochlo briznth Mrndu ws used s forge, intercropped with rice, nd received 90, 72 nd 90 kg h -1 of N, P 2 O 5 nd K 2 O, respectively. In 2010 (My 10) nd 2011 (My 15) soyben crop ws sown nd fertilized, in the CLI system, with 8, 96 nd 48 kg h -1 of N, P 2 O 5 respectively, nd in the coverge were pplied 48 Kg h-1 of K 2 O. The sowing of cover crops lternted between soyben nd Pnicum mximum Tnzni. After 2011, the system remined in psture only. Grin plnting did not occur gin until the dte of our smple collections. In the rottionl psture re (PAST), no correction or soil fertility improvement ws performed, only the mowing of the psture with scythe. The density of the nimls (cttle) corresponded to 60 to 66 individuls per 34 h, divided into eight fenced pstures, with rottion every five dys, within cycle of 35 dys. The originl Semideciduous Sesonl Forest (NF) occurs in environments subjected to periodic wter stress, conditioned to vritions in rinfll. There is n overlp of the Sesonl Forest type with the occurrence of Argissolos nd Ltossolos Amrelos nd Vermelho-Amrelos (Ultisol nd Oxisol) in ll res where this substrte occurs in Rorim. Both soils re well-drined, reltively deep, dystrophic, nd hevily wethered, nd re locted in undulting nd gently undulting reliefs. In the study re, species such s Cnrywood (Centrolobium prense), Ttbu (Diplotropis sp.), Mrup (Simroub mr), Chste tree (Vitex sp.), Breus (Protium sp.) occur on flt topogrphy. Tperebá (Spondi sp.), Cordi (Cordi sp), Purplehert (Peltogyne sp.), nd Pink trumpet tree (Tbebui sp.) occur in undulting topogrphy. Kpok (Ceib pentndr), Tucum (Astrocryum culetum), Cedro espino (Bombcopsis quint). In April 2015, soil smples were collected from trenches t depth intervls of , , , m, using hoe nd stright shovel, with four replictions in ech re of the study or tretment type. Collected soil smples were ir-dried, stripped, nd pssed through 2-mm sieve to obtin ir-dried fine ground (ADFG). The determintion of the C 2+, Mg 2+, K +, N +, Al 3+, H+Al, P, nd ph vlues (in wter) nd grnulometry nlysis were performed ccording to Dongemm et l. (2011). The determintion of TOC (totl orgnic crbon) followed the methodology of Yeomns nd Bremner (1988). The grnulometric frctiontion ws performed ccording to methodology proposed by Cmbrdell nd Elliott (1992), nd ws divided into POC (prticulte orgnic crbon, which consists of the crbon determined in the frction greter thn nm) nd MOC (orgnic crbon ssocited with silt nd cly minerls, which is clculted by the difference between TOC nd POC). The light frction of the orgnic mtter in wter (CMOL) ws determined ccording to the methodology recommended by (ANDERSON; INGRAM, 1989). 2423

6 Gurdiol, M. D. E. et l. A method for determining oxidizble crbon frctions ws proposed by Chn et l. (2001), dpted from the crbon determintion method developed by Wlkley nd Blck (1934). In the originl method, C ws verified by using single concentrtion of sulfuric cid (12 mol L -1 ), but with the chnge suggested by Chn et l. (2001), it ws possible to seprte four frctions with decresing degrees of oxidtion. This ws done by using incresing mounts of sulfuric cid (i.e., the frctions F1, F2, F3, nd F4 were ttributed, respectively, to the concentrtions of 3, 6, 9, nd 12 mol L -1 of sulfuric cid). Humic substnces were quntified using the technique of differentil solubility in humic cids (HA), fulvic cids (FA), nd humin (HUM), ccording to the Interntionl Humic Substnces Society (SWIFT, 1996), using the technique dpted by Benites et l. (2003). The dt were nlyzed for normlity nd homogeneity using the Lilliefors, Cochrn s nd Brtlett s tests. Next, the dt were nlyzed s completely rndomized design. The results were submitted to nlysis of vrince with the ppliction of the F test nd the men vlues, when significnt, were compred with Tukey s test t 5 % probbility. Results nd Discussion The results of the grnulometry nlysis reveled tht the smpled soils rnge from medium to clyey texture, with the vlues of cly incresing with depth (Tble 1). These results gree with the geomorphologicl conditions of the region, s the study re is locted in region of Crystlline Bsement rocks (primrly Grnite/Gneiss), positioned in smooth-to-undulting to undulting relief, under Semideciduous Sesonl Forest. The chemicl ttributes of the different study res re presented in Tble 2. Despite their similr geologic origin (Grnite/Gneiss), the soils formed from these rocks hve better chemicl qulity thn soils in the centrl portion of the stte (formed primrily from sedimentry rocks). High rinfll, in ssocition with the locl topogrphy (smooth-to-undulting to undulting relief), encourges significnt fertility losses (vi leching) throughout the study re, resulting in soils with low nturl fertility, high sturtion by luminum, nd low sturtion by bses. However, the soils do possess dequte morphologicl nd physicl chrcteristics, tht when mnged to retin fertility, cn provide good griculturl production indices (VALE JÚNIOR; LEITÃO SOUSA, 2005). The ph vlues vried from 4.6 to 5.8, chrcterizing these soils s modertely cidic (RAIJ; QUAGGIO, 1983). The vlues of ph in surfce soil (depths of nd m) in the PAST, CLI nd CLFI systems did not vry sttisticlly; however, they differed sttisticlly from NF, which presented the lowest ph vlue t the soil surfce. This difference my be due to the fct tht soil mendments hve never been pplied to NF. The vlues of potentil cidity found corroborte to the ph vlues in ech of the environments studied, in greement with the low exchngeble bse vlues found. The highest levels of Al 3+ were mesured in upper 0.2 m of NF. The proper use of liming nd the reduction of minerl fertilizers in psture or griculturl systems my result in low levels of luminum in the soil, nd so the high levels of luminum we found in NF is not surprising. 2424

7 Chemicl nd physicl frctions of soil orgnic mtter under vrious mngement regimes in Rorim, Brzil Tble 2. Chemicl chrcteriztion of soils under different mngement systems, seven yers fter implementtion, in the Semidecidul Sesonl Forest Region, Rorim, Brzil. Tretments ph em H 2 O P K + C 2+ Mg 2+ N + Al 3+ (H+Al) mg dm cmol c /dm ,10 m PAST 5,7 3,0 b 0,15 1,4 1,23 0,13 0,17 b 2,2 c NF 4,6 b 3,0 b 0,19 0,8 b 0,21 b 0,12 0,68 3,0 bc CLI 5,5 10,0 0,25 1,5 0,71 b 0,15 0,18 b 3,7 b CLFI 5,8 10,0 0,24 b 1,5 0,47 b 0,13 0,18 b 4,0 0,10-0,20 m PAST 5,7 2,0 0,18 0,9 0,83 0,10 0,36 b 1,2 b NF 4,6 b 2,0 0,21 0,5 0,44 0,15 0,56 3,8 CLI 5,4 4,0 0,23 1,4 0,20 0,16 0,15 bc 2,9 CLFI 5,7 4,0 0,11 b 1,3 0,36 0,08 0,06 c 1,9 b 0,20-0,40 m PAST 5,7 2,0 0,11 b 0,9 0,48 0,11 0,23 b 1,3 c NF 4,8 2,0 0,19 1,0 0,16 0,15 0,67 2,9 b CLI 5,3 3,0 0,23 1,3 0,16 0,16 0,23 b 3,0 CLFI 5,5 1,0 0,12 b 0,7 b 0,51 0,09 0,31 b 1,9 bc C.V % 9,07 34,51 21,2 33,53 61, ,29 Averges followed by equl letters in the column for the sme depth do not differ (Tukey s test t 5 % probbility). PAST (rottionl psture re), NF (nturl forest), CLI (crop-livestock integrtion system), nd CLFI (crop-livestock-forest integrtion system). The men vlues of C 2+ nd Mg 2+ (Tble 2) rnged from 0.5 to 1.5 cmol c dm -3 for C 2+ nd from 0.16 to 1.23 cmol c dm -3 for Mg 2+. The nutrient contents in soils of CLI, CLFI, nd PAST systems were higher thn in NF, especilly in the m depth rnge. The concentrtions of C 2+ nd Mg 2+ we mesured in the upper 0.4 m of soil would clssify this soil s being low to very low, ccording to the clssifiction proposed by Arújo et l. (2011). In these soils, the low ction exchnge cpcity (CEC) is cused by the predominnce of low ctivity clys, ssocited with low orgnic crbon content (SOUZA; MELO, 2003). Becuse the soils re very wethered (i.e., chemicl nd biologicl ctivity hve occurred in them for thousnds of yers), they hve lost exchngeble bses, resulting in cidic soils (VENDRAME et l., 2011). Totl orgnic crbon (TOC) dt re presented in Tble 3. TOC content decresed in depth nd rnged from 4.3 to 15.6 g kg -1 in the m depth lyer, nd 4.5 to 0.3 g kg -1 t the depth of m. In the depth rnge of m, the PAST nd CLI mngement systems presented the highest TOC levels reltive to the other systems studied; t the other depths there were no sttisticl differences mong the TOC levels. Loss et l. (2009) verified tht vrious soil mngement systems, depending on climtic conditions, provide different mounts of plnt residues to the soil. In res with lower mounts of vegetl remins, ssocited with hot nd humid summers) climtic conditions encourge higher decomposition rtes nd higher rtes of chemicl rections in the soil. Furthermore, rpid minerliztion of SOM leds to different TOC levels, especilly in upper soil lyers. In studies on the lbile nd reclcitrnt frctions of orgnic mtter in soils under CLI mngement, Silv et l. (2011) verified tht fter with 4 nd 8 yers of production, the systems presented TOC mounts equl to those of no-tillge system 23 yers fter implementtion. Is this crop rottion of plnts of different fmilies in the CLI system 2425

8 Gurdiol, M. D. E. et l. is ssocited with higher input nd higher preservtion of plnt residues. Moreover, grsses, minly Pocee, re effective in the contribution nd ccumultion of crbon in soils, due to its bundnt nd voluminous root system, which is continully renewed; in ddition, the high rhizospheric volume of grss roots increses root ctivity nd modifies in the microbil popultion (D ANDRÉA et l., 2004). Tble 3. Totl orgnic crbon (TOC), prticulte orgnic crbon (POC) nd orgnic crbon ssocited with the minerls (MOC) of soils under different mngement, seven yers fter implementtion, in the Semidecidul Sesonl Forest Region, Rorim, Brzil. TOC g kg -1 Sistems Depth (m) 0-0,10 0,10-0,20 0,20-0,40 0,40-0,60 PAST 15,6 A 7,3 B 5,5 BC 3,8 CD NF 9,3 ca 7,8 AB 5,0 B 4,5 BC CLI 14,3 ba 8,5 B 4,8 C 4,3 C CLFI 13,3 ba 6,7 B 4,3 C 4,5 BC C.V.% 18,71 27,12 17,17 17,47 POC g kg -1 PAST 3,6 A 1,5 B 1,3 BC 1,5 B NF 2,3 ca 1,5 BC 1,0 BC 0,3 cc CLI 2,8 bca 1,5 AB 0,8 B 0,8 bcb CLFI 3,0 bca 1,0 B 0,8 B 0,8 bcb C.V% 49,73 45,59 50,4 43,42 MOC g kg -1 PAST 12,0 A 5,8 B 4,2 BC 2,3 CD NF 7,0 ba 6,3 AB 4,0 BC 4,2 ABC CLI 11,5 A 7,0 B 4,0 C 3,5 C CLFI 10,3 A 5,7 B 3,5 C 3,7 BC C.V% 16,34 27,56 17,93 25,75 Vlues followed by equl letters (lower cse) in the column nd equl letters in the row (upper cse) for the sme vrible do not differ (Tukey s test t 5 % probbility). PAST (rottionl psture re), NF (nturl forest), CLI (crop-livestock integrtion system), nd CLFI (crop-livestock-forest integrtion system). Prticulte orgnic crbon (POC) is chrcterized by prticles derived from decomposing plnt residues nd hyphe of fungi. The permnence of POC in the soil depends on how well the soil is protected physiclly (LOSS et l., 2011). In our study, the highest mount of C in the prticulte frction (POC) ws verified in the surfce lyer in ll the mngement systems we evluted, with vlues rnging from 3.6 to 1.0 in the surfce-to-0.20 m lyer nd from 1.5 to 0.3 in the m lyer (Tble 3). Mnged psture ws the system with the highest contribution of POC t the m depth nd its contents were lso significntly higher in the m depth rnge. It is importnt for soils to mintin dequte mounts of prticulte crbon to ensure the flow of crbon to the soil nd provide n energy source for microbil ctivity. In the bsence of lbile orgnic mtter, crbon oxidtion processes decrese crbon stocks, which leds to soil degrdtion (CAUSARANO et l., 2008). Studies on soil orgnic mtter frctions under psture, no-tillge system, nd crop-livestock integrtion mngement in the Cerrdo Goino Region showed the highest POC content in the 2426

9 Chemicl nd physicl frctions of soil orgnic mtter under vrious mngement regimes in Rorim, Brzil superficil lyer in CLI system (when compred to psture nd no-till mngement types). SOM lso presented higher levels of POC when compred to the Cerrdo in the m soil lyers (GAZOLLA et l., 2015). The uthors ttributed this result to the use of the brchiris rotted with corn crop, since this mngement type provides higher nnul ddition nd mintennce of the vegetl residues into the soil surfce horizons reltive to no-tillge nd PAST mngement types. These results lso corroborte with dt obtined by Loss et l. (2011) nd Rossi et l. (2012), who evluted no-tillge res with nd without CLI in Ltossolo Vermelho (Oxisol) (in the Stte of Goiás) nd found higher POC vlues in res of CLI thn in no-tillge res. Slton et l. (2008), studying the content nd dynmics of crbon in soils under CLI, verified the highest mount of C in the prticulte frction in the surfce lyer of ll mngement systems. The uthors lso verified higher contribution in POC in the psture re (in the top m strtum), while the conventionl plnting system hd five times lower POC levels. Our results showed tht in the depth rnge of m, NF hd the lowest C levels ssocited with MOC compred to the other mngement systems we studied. Gzoll et l. (2015) nd Loss et l. (2011) verified higher contribution of the orgnic crbon frction ssocited with the minerls (MOC) in CLI systems in their studies in the Cerrdo Goino. They ttributed this results to the use of brchiri in the CLI system they studied, ssocited with the Fe nd Al oxides, which my provide better conditions for the formtion of microggregtes, nd thus greter protection for the MOC frction. The highest contribution of crbon in humic substnces occurred in the humin frction (HUM), to the detriment of the FA nd HA frctions in ll systems studied (Figure 1). This result my be ttributed to the greter prticiption of humin, which represents bout 70 % of the TOC. Humin frctions re considered to be the most reclcitrnt portions in the soil nd so hve higher potentil for interction with its colloidl minerl mtrix (ARAÚJO et l., 2011). In ddition, the frctions AF nd AH re less stble nd they re esily minerlized in soil, which reduces their residul content (FONTANA et l., 2006). At the depth of m, the PAST nd CLI mngement types presented the highest HUM contents when compred with CLFI nd NF types. Brreto et l. (2011), studying cco cultivtion in n Atlntic Forest nd psture system in Brchiri, verified tht the highest percentge of orgnic C ws observed in the humin frction. Likewise, in our study the highest orgnic C contents in this frction were in the psture re t m depth, where the gretest contribution of the fsciculte root system of the grsses occurs. These grsses must rise nd mintin soil C inputs nd llow stbiliztion of the C in the humin frction. In our study, the highest contribution oxidizble frctions ws in F1 frction, but there were no significnt differences between the mngement systems we evluted (Figure 2). Among the different mngement types, only F3, F4 nd CMOL frctions were observed, with the lowest levels found in the NF system. 2427

10 Gurdiol, M. D. E. et l. Figure 1. Humic substnces crbon (g kg -1 ) of soils under different mngement systems, seven yers fter implementtion, in the Semidecidul Sesonl Forest Region, Rorim, Brzil. h f hum Humic Substnces (g kg -1 ) PAST FN NF CLI ILP IFLP CLFI Tretments PAST (rottionl psture re), NF (nturl forest), CLI (crop-livestock integrtion system), CLFI (crop-livestock-forest integrtion system), HA (humic cid), FA (fulvic cid), nd Hum (humin). Averges followed by the sme letter do not differ (Tukey s test t 5 % probbility). Figure 2. Oxidizble frctions nd crbon in the light frction of the orgnic mtter (g kg -1 ) of soils under different mngement systems, seven yers fter implementtion, in the Semidecidul Sesonl Forest Region, Rorim, Brzil. COT TOC (g g kg -1-1 ) 2 1,8 1,6 1,4 1,2 1 0,8 0,6 F1 F2 F3 F4 MOL b b b b b b b 0,4 0,2 b 0 PAST F.N NF FN CLI ilp ILP CLFI ilpf IFLP Tretments PAST (rottionl psture re), NF (nturl forest), CLI (crop-livestock integrtion system), nd CLFI (crop-livestock-forest integrtion system), CMOL (light orgnic mtter in wter), nd F1, F2, F3, nd F4 (frctions of orgnic mtter in different degrees of oxidtion t concentrtions of 3, 6, 9 nd 12 mol L -1 of sulfuric cid, respectively). Averges followed by the sme letter do not differ (Tukey s test t 5 % probbility). 2428

11 Chemicl nd physicl frctions of soil orgnic mtter under vrious mngement regimes in Rorim, Brzil The mngement systems tht dd orgnic mtter to the soil (vi input of decomposition of vegettion) tend to increse the F1 frction (MORAES et l., 2008) due to the free light frction of SOM (MAIA et l., 2007). In this study, the highest proportions of TOC occurred in the F1 nd F4 frctions. Higher TOC in F4 frction my be relted to slower relese of C, which corresponds to more resistnt frction of orgnic crbon. Loss et l. (2009) mentioned tht the highest proportions of TOC in F1 nd F2 frctions might be minly ttributed to the contribution nd decomposition of the most lbile plnt residues dded to the soil. In this cse, the permnence of these frctions in soils is low, due to their lower C/N rtio, so the more reclcitrnt frctions (F3 nd F4) decompose more slowly nd hve longer hlf-life in soils. In integrted production systems, it would be convenient to hve C blnce between the oxidizble frctions, where the proportions of C between the frctions re similr. Prt of the orgnic mtter is more esily decomposed (with higher minerliztion rtes of nutrients), while nother prt is more persistent in the soil. The more persistent frction improves nd mintins the physicl properties of the soil. However, in tropicl regions with sndy-textured soils, hot nd humid climtes, nd very pronounced riny seson, n increse in the C content of the more resistnt oxidizble frctions (F3 nd F4) would be desirble for slower relese of nutrients nd better crop yields, s well s for improving soil structure (LOSS et l., 2009). For the F3 nd F4 frctions, the CLI, PAST nd CLFI mngement types yielded similr results mong mngement types nd were higher thn in soils of NF. These results indicte tht under the edphoclimtic conditions of the study re, the evluted mngement types hve lrge prt of their TOC distributed in the F3 nd F4 frctions. This distribution is relted to the presence of compounds with higher chemicl stbility nd molr mss, derived from the decomposition nd humifiction of SOM. Zech et l. (1990) determined tht in tropicl soils, the biovilbility of the orgnic mtter is less, wheres orgnic compounds with mny romtic nd crboxylic groups is higher. Our results of CMOL proved tht n increse in the contribution of this frction in the surfce lyer vries ccording to the length of time the mngement system hs been in plce. After 7 yers, soil contents in the m lyer differed from those observed in the NF. This result indictes the gret importnce of the CLI nd CLFI mngement systems in the tropics, in tht the conservtion of CMOL is crucil for the sustinbility of tropicl environments nd their griculturl systems. Our results represent, in short nd medium time frmes, high potentil for nutrient cycling (COMPTON; BOONE, 2002). Conclusions The studied mngement systems mintined the totl orgnic crbon contents of their grnulometric frctions, in ddition, reltive to Nturl Forest the chemicl frctions of the orgnic mtter reveled tht, over time, these gro-mngement systems hve higt potentil for sequestering crbon. Among the humic substnces, n humin (HUM) ws more bundnt frction mong the types of mngement we exmined. This result my be relted to the lrger size nd complexity of the molecules nd to the greter degree of stbility of the frction. References ANDERSON, J. M.; INGRAM, J. S. I. Tropicl soil biology nd fertility: hndbook of methods. Wllingford: CAB Interntionl, p. ARAÚJO, E. A.; KER, J. C.; MENDONÇA, E. S.; SILVA, I. R.; OLIVEIRA, E. K. Impcto d conversão florest - pstgem nos estoques e n dinâmic do crbono e substâncis húmics do solo no biom Amzônico. Act Amzônic, Mnus, v. 41, n.1, p , BALBINO, L. C.; CORDEIRO, M. L. A.; SILVA, V. P.; MORAES, A.; MARTÍNEZ, G. B.; ALVARENGA, R. 2429

12 Gurdiol, M. D. E. et l. C.; KICHEL, A. N.; FONTANELI, R. S.; SANTOS, P. H.; FRANCHINI, J. C.; GALERANI, P. R. Evolução tecnológic e rrnjos produtivos de sistems de integrção lvour pecuári florest no Brsil Blbino Pesquis Agropecuári Brsileir. Brsíli, v. 46, n. 10, p.1-12, BALDOTTO, M. A.; VIEIRA, E. M.; SOUZA, D. de O.; BALDOTTO L. E. B. Estoque e frções de crbono orgânico e fertilidde de solo sob florest, gricultur e pecuári. Revist Ceres, Viços, MG, v. 62, n. 3, p , BARBOSA, R. I. Distribuição ds chuvs em Rorim. In: BARBOSA. R. I.; FERREIRA, E. J. G.; CASTELLÓN, E. G. (Ed.). Homem, mbiente e ecologi no Estdo de Rorim. Mnus: INPA, p BARRETO, P. A. B.; GAMA-RODRIGUES, E. F.; GAMA-RODRIGUES, A. C.; FONTES, A. G.; POLIDORO, J. C.; MOÇO, M. K.; REBOUCA, R. C.; BALIGAR, V. C. Distribution of oxidizble orgnic C frctions in soils under cco groforestry systems in Southern Bhi, Brzil. Agroforestry Systems, Netherlnds, v. 81, n. 3, p , BENITES, V. M.; MADARI, B.; MACHADO, P. L. O. A. Extrção e frcionmento quntittivo de substâncis húmics do solo: um procedimento simplificdo de bixo custo. Rio de Jneiro: Embrp Solos, p. (Comunicdo técnico, 16). BENITES, V. D. M.; MOUTTA, O. R. de; COUTINHO, C. L. d; BALIERO, C. F. de. Análise discriminnte de solos sob diferentes usos em áre de mt tlântic prtir de tributos d mtéri orgânic. Revist Árvore, Viços, MG, v. 34, n. 4, p , BERNOUX, M.; CERRI, C. C.; CERRI, C. E. P.; SIQUEIRA NETO, M.; METAY, A.; PERRIN, A.; SCOPEL, E.; BLAVET, D.; PICCOLO, M. C. Influence du semis direct vec couverture végétle sur l séquestrtion du crbone et l érosion u Brésil. Bulletin Du Réseu Érosion, Pris, v. 23, p , CAETANO, J. O.; BENITES, M. V. de; SILVA, P. G.; SILVA, R. I.; ASSIS, L. R.; CARGNELUTTI, F. A. Dinâmic d mtéri orgânic de um Neossolo qurtzrênico de cerrdo convertido pr cultivo em sucessão de soj e mileto. Revist Brsileir de Ciênci do Solo, Viços, MG, v. 37, n. 5, p , CAMBARDELLA, C. A.; ELLIOTT, E. T. Prticulte soil orgnic-mtter chnges cross grsslnd cultivtion sequence. Soil Science Society of Americ Journl, Mdson, v. 56, n. 3, p , CARVALHO, J. L. N.; AVANZI, J. C.; SILVA, M. L. N.; MELLO, C. R.; CERRI, P. C. E. Potencil de sequestro de crbono em diferentes bioms do Brsil. Revist Brsileir de Ciênci do Solo, Viços, MG, v. 34, n. 2, p , CAUSARANO, H. J.; FRANZLUEBBERS, A. J.; SHAW, J. N.; REEVES, D. W.; RAPER, R. L.; WOOD, C. W. Soil orgnic crbon frctions nd ggregtion in the Southern Piedmont nd costl plin. Soil Wter Mngement & Conservtion Division, Mdson, v. 72, n. 1, p , CHAN, K. Y.; BOWMAN, A.; OATES, A. Oxidizible orgnic crbon frctions nd soil qulity chnges in n Pleustlf under different psture leys. Soil Science, Bltmore, v. 166, n. 1, p , COMPTON, J. E.; BOONE, R. D. Soil nitrogen trnsformtions nd the role of light frction orgnic mtter in forest soils. Soil Biology nd Biochemistry, Elmsford, v. 34, n. 7, p , CONCEIÇÃO, P. C.; AMADO, T. J. C.; MIELNICZUK, J.; SPAGNOLLO, E. Qulidde do solo em sistems de mnejo vlid pel dinâmic d mtéri orgânic e tributos relciondos. Revist Brsileir de Ciênci do Solo, Viços, MG, v. 29, n. 5, p , D ANDRÉA, A. F.; SILVA, M. L. N.; CURI, N.; GUILHERME, L. R. G. Estoque de crbono e nitrogênio e forms de nitrogênio minerl em um solo submetido diferentes sistems de mnejo. Pesquis Agropecuári Brsileir, Brsíli, v. 39, n. 2, p , DONAGEMMA, G. K.; CAMPOS, D. V. B.; CALDERANO, S. B.; TEIXEIRA, W. G.; VIANA, J. H. M. (Org.). Mnul de métodos de nálise de solo. Rio de Jneiro: CNPS, p. FERREIRA, A. O.; MORAES SÁ, J. C.; HARMS, M. G.; MIARA, S.; BRIEDIS, C.; NETTO, C. Q.; SANTOS, J. B.; CANALLI, L. B. Crbon blnce nd crop residue mngement in dynmic equilibrium under no-till system in Cmpos Geris. Revist Brsileir de Ciênci do Solo, Viços, MG, v. 36, n. 5, p , FIGUEIREDO, C. C. de; RESCK, D. V. S.; CARNEIRO, M. A. C. Lbile nd stble frctions of soil orgnic mtter under mngement systems nd ntive cerrdo. Revist Brsileir de Ciênci do Solo, Viços, MG, v. 34, n. 3, p , FONTANA, A.; PEREIRA, M. G.; LOSS, A.; CUNHA, T. J. F.; SALTON, J. C. Atributos de fertilidde e frções húmics de um Ltossolo Vermelho no Cerrdo. Pesquis Agropecuári Brsileir, Brsíli, v. 41, n. 5, p , FRAZÃO, L. A.; SANTANA, I. K. S.; CAMPOS, D. V. B.; FEIGL, B. J.; CERRI, C. C. Estoques de crbono e 2430

13 Chemicl nd physicl frctions of soil orgnic mtter under vrious mngement regimes in Rorim, Brzil nitrogênio e frção leve d mtéri orgânic em Neossolo Qurtzrênico sob uso grícol. Pesquis Agropecuári Brsileir, Brsíli, v. 45, n. 10, p , GAZOLLA, P. R.; GUARESCHI, R. P.; PERIN, A.; PEREIRA, M. G.; ROSSI, M. G. Frções d mtéri orgânic do solo sob pstgem, sistem plntio direto e integrção lvour-pecuári. Semin: Ciêncis Agráris, Londrin, v. 36, n. 2, p , KLUTHCOUSKI, J.; OLIVEIRA, P. Benefícios d ILP pr pecuári e desfios no cultivo de grndes culturs em sistems ILPF no Cerrdo com uso de plntio direto n plh. In: SANTOS, L. F. T.; MENDES, L. R.; DUARTE, E. R.; GLÓRIA, J. R.; ANDRADE, J. M.; CARVALHO, L. R.; SALES, N. L. P. (Ed.). Integrção lvour-pecuári florest: potenciliddes e técnics de produção. Montes Clros: Instituto de Ciêncis Agráris d UFMG, p LOSS, A.; PEREIRA, M. G.; ANJOS, L. H. C.; GIACOMO, S. G.; PERIN, A. Agregção, crbono e nitrogênio em gregdos do solo sob plntio direto com integrção lvour-pecuári. Pesquis Agropecuári Brsileir, Brsíli, v. 46, n. 10, p , LOSS, A.; PEREIRA, M. G.; FERREIRA, E. P.; SANTOS, L. L. dos; BEUTLER, S. J.; FERRAZ- JUNIOR, A. S. L. Frções oxidáveis do crbono orgânico em Argissolo Vermelho-Amrelo sob sistem de leis. Revist Brsileir de Ciênci do Solo, Viços, MG, v. 33, n. 4, p , MAIA, S. M. F.; XAVIER, F. A. S.; SENNA, O. T.; MENDONCA, E. S.; ARAUJO, J. A. Orgnic crbon pools in Luvisol under groforestry nd conventionl frming systems in the semi-rid region of Cerá, Brzil. Agroforestry Systems, Dordrecht, v. 71, n. 2, p , MORAES, A. G. L.; LOSS, A.; PEREIRA, M. G.; BERNINI, T. A.; ANJOS, L. H. C.; SANTOS, L. L.; WADT, P. G. Frções oxidáveis de crbono orgânico de horizontes superficiis em topossequênci sob florest no Acre. In: FERTBIO, DESAFIOS PARA O USO DO SOLO COM EFICIÊNCIA E QUALIDADE AMBIENTAL, 2008, Londrin. Anis... Londrin: CD-ROM. PAUL, B. K.; VANLAUWE, B.; AYUKE, F.; GASSNER, A.; HOOGMOED, M.; HURISSO, T. T.; KOALA, S.; LELEI, D.; NDABAMENYE, T.; SIX, J.; PULLEMAN, M. M. Medium-term impct of tillge nd residue mngement on soil ggregte stbility, soil crbon nd crop productivity. Agriculture, Ecosystems nd Environment, Netherlnds, v. 164, n. 1, p , RAIJ, B. vn; QUAGGIO, J. A. Métodos de nálise de solo pr fins de fertilidde. Cmpins: Instituto Agronômico de Cmpins, p. (Circulr, 63). ROSSI, C. Q.; PEREIRA, M. G.; GIÁCOMO, S. G.; BETTA, M.; POLIDORO, J. C. Frções lábeis d mtéri orgânic em sistem de cultivo com plh de brquiári e sorgo. Revist Ciênci Agronômic, Fortlez, v. 43, n.1, p , SALES, L. E. O.; CARNEIRO, M. A. C.; SEVERIANO, E. C.; OLIVEIRA, G. C.; FERREIRA, M. M. Qulidde físic de Neossolo Qurtzrênico submetido diferentes sistems de uso grícol. Ciênci e Agrotecnologi, Lvrs, v. 34, n. 3, p , SALTON, J. C.; MIELNICZUK, J.; BAYER, C.; BOENI, M.; CONCEIÇÃO, P. C.; FABRICIO, A. C.; MACEDO, M. C. M.; BROCH, D. L. Agregção e estbilidde de gregdos do solo em sistems gropecuários em Mto Grosso do Sul. Revist Brsileir de Ciênci do Solo, Viços, MG, v. 32, n. 1, p , SANTOS, H. G. dos; JACOMINE, P. K. T.; ANJOS, L. H. C. dos; OLIVEIRA, V. A. de; LUMBRERAS, J. F.; COELHO, M. R.; ALMEIDA, J. A. de; CUNHA, T. J. F.; OLIVEIRA, J. B. de. Sistem brsileiro de clssificção de solos. 3. ed. rev. e mpl. Brsíli: Embrp, p. SILVA, V. J.; CAMARGO, R.; WENDLING, B.; PIRES, S. C. Integrção lvour-pecuári sob sistem de plntio direto no Cerrdo brsileiro. Enciclopédi Biosfer, Goini, v. 7, n. 1, p. 1-12, SOUZA, W. J. O.; MELO W. J. Mtéri orgânic em um ltossolo submetido diferentes sistems de produção de milho. Revist Brsileir de Ciênci do Solo. Viços, v. 27, n. 6, p , SWIFT, R. S. Orgnic mtter chrcteriztion. In: SPARKS, D. L. (Ed.). Methods of soil nlysis. Prt 3. Mdison: Chemicl Methods SSSA, p VALE JÚNIOR, J. F.; LEITÃO SOUSA, M. I. Crcterizção e distribuição dos solos ds svns de Rorim. In: BARBOSA, R. I.; XAUD, H. A. M.; SOUZA, J. M. C. Svns de Rorim: etnoecologi, biodiversidde e potenciliddes grosivipstoris. Bo Vist: FERMACT, p. VENDRAME, P. R. S.; EBERHARDT, D. N.; BRITO, O. R.; MARCHÃO, R. L; QUANTIN, C.; BECQUER, T. Forms de ferro e lumínio e sus relções com textur, minerlogi e crbono orgânico em Ltossolos do Cerrdo. Semin: Ciêncis Agráris, Londrin, v. 32, n. 1, p , WALKLEY, A.; BLACK, A. An exmintion of the Degtjreff method for determining soil orgnic mtter 2431

14 Gurdiol, M. D. E. et l. nd proposed modifiction of the chromic cid titrtion method. Soil Science, Bltimore, v. 37, n. 1, p , YEOMANS, J. C.; BREMNER, J. M. A rpid nd precise method for routine determintion of orgnic crbon in soil. Communiction in Soil Science nd Plnt Anlysis, New York, v. 19, n. 13, p , ZECH, W.; HAUMAIER, L.; HEMPFLING, R. Ecologicl spects of soil orgnic mtter in tropicl lnd use. In: McCARTHY, P.; CLAPP, C. E.; MALCOM, R. L.; BLOOM, P. R. (Ed.). Humic substnces in soil nd crop sciences: selecting redings. Mdison: ASA/SSSA, p