Aggregate stability and penetration resistance after mobilization of a dystrocohesive Ultisol

Transcrição

1 ISSN Revist Brsileir de Engenhri Agrícol e Amientl v.21, n.11, p , 217 Cmpin Grnde, PB, UAEA/UFCG DOI: Aggregte stility nd penetrtion resistnce fter moiliztion of dystrocohesive Ultisol Uilk E. Tvres 1, Mrio M. Rolim 1, Djlm E. Simões Neto 2, Elvir M. R. Pedros 1, Adrin G. Mglhães 1 & Ênio F. de F. e Silv 1 1 Universidde Federl Rurl de Pernmuco/Deprtmento de Engenhri Agrícol. Recife, PE. E-mil: uetvres@yhoo.com.r; mrio.rolim@ufrpe.r (Corresponding uthor); elvir.pedros@ufrpe.r; gmguedes@gmil.com; effsilv@ufrpe.r 2 Universidde Federl Rurl de Pernmuco/Estção Experimentl de Cn-de-çúcr de Crpin. Crpin, PE. E-mil: desn@oi.com.r Key words: furrowing hrrowing soil resistnce A B S T R A C T Evlution of moilized soil profiles cn provide importnt informtion on soil compction reduction processes. In this context, the ojective of this study ws to evlute ltertions in soil penetrtion resistnce nd the impct on the ggregte stility of cohesive Ultisol cultivted with sugrcne. The experiment ws crried out t the Crpin Sugrcne Experimentl Sttion (EECAC/UFRPE), locted in the city of Crpin, PE. Penetrtion resistnce, moilized re nd depth, nd percentge of soil ggregtes were evluted efore nd fter soil tillge. Soil moiliztion improved soil ggregte uniformity nd decresed penetrtion resistnce in the -.2 m lyer. Corse soil frction, moisture nd orgnic cron positively contriuted to the increse in soil moiliztion. Plvrs-chve: sulcgem grdgem resistênci do solo Estilidde de gregdos e resistênci à penetrção pós moilizção de um Argissolo Amrelo distrocoeso R E S U M O A vlição dos perfis moilizdos do solo pode fornecer informções sore os processos de redução d compctção do solo. Neste contexto, o ojetivo do presente estudo foi vlir lterções n resistênci à penetrção e o impcto sore estilidde de gregdos de um Argissolo Amrelo cultivdo com cn-de-çúcr. O experimento foi relizdo n Estção Experimentl de Cn-de-çúcr do Crpin (EECAC/UFRPE), no Município de Crpin, PE. Medids d resistênci à penetrção, áre e profundidde moilizd, e percentul de gregdos do solo form relizds ntes e pós o prepro do solo. O sistem de prepro permitiu mior uniformidde ns clsses de gregdos e reduziu resistênci à penetrção n cmd -,2 m. A frção gross do solo, umidde e o crono orgânico contriuírm positivmente pr mior áre moilizd e profundidde do perfil. Ref Received 22 Dec, 216 Accepted 28 Apr, 217 Pulished 26 Sep, 217

2 Aggregte stility nd penetrtion resistnce fter moiliztion of Ultisol 753 Introduction Brzil is the lrgest sugrcne producer in the world, which hs plced the country lso s the lrgest sugr producer nd exporter (FAO, 216) nd second lrgest ethnol producer (Mrin & Nssif, 213). In order to meet the demnd for inputs, the griculturl production system hs intensified soil tillge nd mechnized hrvest, iming to provide fvorle environment to crop growth, increment in yield nd reduction of costs (Hsn, 212; Souz, 212; Vischi Filho et l., 215). Kumr et l. (212) oserved improvement in sugrcne yield with susoiling of two soils in Indi nd found tht tillge ws eneficil to reduce compction nd hve lower costs, compred with other prctices. However, studies indicte tht, in cses of excessive intensity, frequency nd/or durtion in the use of vehicles nd implements, there my e destruction of the nturl structure of the soil nd its ggregtes, reduction in totl porosity nd processes of compction (Mrtins et l., 213; Bott et l., 216). When the soil is compcted, its porosity nd ertion decrese nd its resistnce to root penetrtion increses (Rmos et l., 213). Hsn (212) found increment in penetrtion resistnce, due to trffic, of 1, 51 nd 15% t depths of 1, 2 nd 3 cm, respectively, nd indicted moldord plow s the most efficient implement to reduce penetrtion resistnce in the studied soil. This uthor lso ssocited the pssing of trctor to the increment in resistnce to penetrtion nd reduction in plnt growth nd yield. Studies hve demonstrted higher levels of ggregte stility in soil under no-tillge system compred with conventionl tillge (Hickmnn et l., 211) nd significnt reltionship with soil properties, such s texture, moisture, dispersed cly, porosity nd orgnic cron (Vicente et l., 212). Bsed on these properties, soil ggregtes re pointed s good indictors of soil qulity (Tormen et l., 28). The ojective of the present study ws to evlute ltertions in penetrtion resistnce nd ggregte stility due to tillge system in dystrocohesive Ultisol cultivted with sugrcne. Mteril nd Methods The study ws crried out t the Crpin Sugrcne Experimentl Sttion (EECAC/UFRPE), situted in the municiplity of Crpin-PE, Brzil (7º 51 S; 35º 14 W; 178 m). The climte of the region, ccording to Köppen s clssifiction, is As, tropicl riny with dry summer. According to the verge vlues (Tle 1), the soil ws clssified s sndy lom (Lemos & Sntos, 1996). The experimentl re hs rectngulr shpe of pproximtely.88 h, divided into grid of 16 experimentl plots of m, spced y 2. m, nd is locted in dystrocohesive Ultisol, ccording to EMBRAPA (213). Initilly, the studied re hd een for 5 yers under sugrcne cultivtion nd successive trffic of vehicles. Soil smples were collected t two times: T1 - efore soil moiliztion nd T2 - fter soil moiliztion. Soil moiliztion in T2 corresponded to the ppliction of two soil tillge systems: P1 - hrrowing + furrowing; nd P2 - furrowing. Two sugrcne vrieties were selected nd rndomly cultivted in ech tillge system: RB nd RB At two estlished periods, T1 nd T2, nd in the centrl point of ech experimentl plot, soil smples were collected to determine physicl nd chemicl ttriutes. Orgnic cron contents (OC), plsticity limit (PL), liquidity limit (LL) nd plsticity index (PI), nd soil texture, density (Ds) nd moisture (w) were determined ccording to the methodology of EMBRAPA (211). In the comprison with soil moiliztion, the following vriles were quntified: orgnic cron contents (OC), plsticity limit (PL), moisture during soil tillge (w ST ) nd corse snd content. Penetrtion resistnce (PR) test ws conducted t times T1 nd T2, in the centrl point of the plot, using reduced impct penetrometer (model IAA/Plnlsucr-Stolf) with cone ngle of 3. The device s rod penetrtion in the soil (cm per impct) ws trnsformed into penetrtion resistnce, in MP, ccording to Stolf, using Eq. 1: M Mg + mg + M+ m PR = A (1) where: PR - soil penetrtion resistnce, kgf cm -2 (kgf cm = MP); M - hmmer mss, 1.6 kg (Mg kgf); m - mss of the device without hmmer, 1.47 kg (Mg kgf); h - hmmer fll height, 26 cm; x - device s rod penetrtion, cm per impct; nd, A - cone re, 1.35 cm². Moilized re (MA) nd furrow depth were determined using profilometer, ccording to Crvlho Filho et l. (28); digitl photogrphs recorded the distriution of the profilometer s stylus long the soil profile efore nd fter moiliztion. The verticl distnce etween furrow ottom nd soil surfce corresponded to its mximum depth. Aggregte stility ws nlyzed y wet sieving in Yoder pprtus. The results, expressed in the clsses > 2, 2-1, 1-.5,.5-.25, <.25 mm, were used to clculte men weight dimeter (MWD), fineness modulus (FM) nd percentge of ggregtes, t 2. mm (AGRI ), ccording to Freire & Piedde Tle 1. Chemicl nd physicl chrcteriztion of dystrocohesive Ultisol cultivted with sugrcne Cly Fine snd Corse snd Silt Ds W ST θfc K N C Mg g kg -1 g cm -3 % cmol c dm - ³ ph.-.2 m m Ds - Soil ulk density; W ST - Moisture during soil tillge; θfc - Moisture t field cpcity; N - Sodium; K - Potssium; C - Clcium; Mg - Mgnesium R. Brs. Eng. Agríc. Amientl, v.21, n.11, p , 217.

3 754 Uilk E. Tvres et l. Júnior (1979), Kemper & Rosenu (1986), nd Wendling et l. (25), respectively. Soil moiliztion times (efore nd fter soil tillge) were evluted sed on covrince nlysis using the SAS sttisticl softwre. The dt otined fter soil tillge were sujected to nlysis of vrince in rndomized lock design in split-plot scheme, nd tretment mens were compred y Tukey test t.5 proility. Plots corresponded to soil tillge systems (P1 - hrrowing + furrowing; P2 - furrowing) nd suplots to two sugrcne vrieties (V1 - RB ; V2 - RB92 579), totlizing 4 tretments (P1V1, P1V2, P2V1, P2V2), with four replictes. Results nd Discussion The results for Ds, w, OC, PR, MWD nd FM re presented in Tle 2. Since the T1 condition (efore moiliztion) hs no tretment, only the overll men nd its stndrd error re presented. PR showed vlue of 2 MP, considered s high y Soil Survey Stff (1993), in oth lyers. The oserved MWD is higher thn tht found y Vicente et l. (212) in oth lyers, ut similr to tht found y Hickmnn et l. (211) in res with lower soil moiliztion. The higher the proportion of lrger ggregtes, the higher the MWD. Hickmnn et l. (211) showed tht the doption of prctices with lower soil moiliztion, such s no-tillge, promoted 3% increse in MWD in soils worked with disc plow + hevy hrrow, for two decdes. Such positive increment in MWD due to the lower soil disturnce cn e oserved in the present study fter soil moiliztion with different implements (Tle 3). After soil moiliztion with the ppliction of soil tillge tretments nd sugrcne vrieties, there ws no interction etween oth fctors nd the isolted effects of soil tillge nd sugrcne vrieties were not significnt on the vriles Ds, w, OC, PR, MWD nd FM, in oth lyers, except for the interction on FM nd MWD in the.2-.4 m lyer nd for soil tillge on w nd PR in the -.2 m lyer (Tle 3). The non-significnt effect on FM nd MWD in the -.2 m lyer in this study corroortes other studies (Vicente et l., 212; Oliveir et l., 21), especilly FM in res cultivted with sugrcne nd without vinsse ppliction (Vicente et l., 212). FM nd MWD were not good indictors to differentite the conditions of ntive forest nd soil fertigted with vinsse in the lyers of -.2 m nd.2-.4 m (Oliveir et l., 21), confirming the etter pplicility of FM to evlute dry ggregte stility. Covrince nlysis showed significnt difference etween T1 nd T2 for PR, MWD nd FM in surfce (men vlues of Tle 2. Soil density (Ds), moisture (W), orgnic cron (OC), penetrtion resistnce (PR), men weight dimeter (MWD), fineness modulus (FM), for the time T1 (efore soil tillge) Ds W OC PR MWD gcm -3 % dg kg -1 MP mm FM -.2 m Men Stndrd error m Men Stndrd error Tle 3. Soil density (Ds), moisture (W) orgnic cron (OC) penetrtion resistnce (PR), men weight dimeter (MWD) nd fineness modulus (FM) for the interction Soil tillge x sugrcne vrieties nd their isolted effects fter soil moiliztion t time T2 Ds W OC PR MWD g cm -3 % dg kg -1 MP mm FM -.2 m P1V P1V P2V P2V Men * 2.66* 3.26* V V P P m P1V P1V P2V P2V Men V V P P Sme lowercse letters in the column for ech P V comintion, V nd P do not differ y Tukey test t.5 proility level; *Significnt y the covrince nlysis of the men of T1 (Tle 2) for T2; T1 - Before soil tillge; T2 - After soil tillge; P1 - Hrrowing + Furrowing; P2 - Furrowing; V1 - RB ; V2 - RB Tles 2 nd 3), in which soil moiliztion with hrrow nd furrower led to reduction in PR, MWD nd FM, nd reduced the percentge of the ggregte clsses. Thus, considering the results found y Vicente et l. (212) nd Oliveir et l. (21), it cn e inferred for the present study tht FM nd MWD cn e good indictors of ggregte stility when the soil hs een recently moilized nd compred with its previous condition of moiliztion, regrdless of orgnic cron contents. According to Medvedev (29), PR ws more sensitive soil ttriute to chrcterize soil tillge thn Ds. The interction etween oth tretments did not led to sttisticl difference in soil physicl or chemicl ttriutes, most likely ecuse of the implements used nd the reduced cultivtion time (one cycle) of oth sugrcne vrieties (Tle 3). In similr study, Vizzotto (214) found tht shnk-type furrowers reduced Ds, incresed totl porosity in the crop row nd cused lrger surfce nd volume of moilized soil. There ws sttisticl difference for the ggregtes (Figure 1). Aggregtes with lrger dimeter (> 2 mm) re found in surfce, nd differences etween tretments were more evident in this lyer. Reduction in this clss of ggregtes, s soil depth increses, my e relted to the reduction in the orgnic mtter content long soil depth, s oserved y Oliveir et l. (21). Aggregtes with smller dimeter previled in susurfce (Figures 1A nd B). At T2, significnt difference occurred for ggregtes > 2 mm nd in the intervl mm, in oth lyers, nd ggregtes <.25 mm in the.2-.4 m lyer. However, the clss of 2-1 mm ggregtes did not present vrition etween tretments, collection times or soil lyers. On the other hnd, in the.2-.4 m lyer, ggregtes <.25 mm showed higher occurrence. This result my e relted to the orgnic cron (OC), which contriuted to soil ggregtion R. Brs. Eng. Agríc. Amientl, v.21, n.11, p , 217.

4 Aggregte stility nd penetrtion resistnce fter moiliztion of Ultisol 755 Stle ggregtes in wter (%) Stle ggregtes in wter (%) A. B. c P1V1 P1V2 P2V1 P2V2 T1 P1V1 P1V2 P2V1 P2V2 T1 > <.25 Clss of ggregtes (mm) Sme lowercse letters do not differ y Tukey test t.5 proility level for the pplied tretments. T1 - Before soil tillge; P1 - Hrrowing + Furrowing; P2 Furrowing; V1 vriety RB ; V2 vriety V2 RB Figure 1. Aggregte distriution efore nd fter soil moiliztion in the lyers of -.2 (A) nd.2-.4 m (B) in surfce fter moiliztion, due to the higher cly content in susurfce, promoting cementing effect on the ggregtes. Soil tillge with hrrow nd furrower (P1) led to reductions in PR of 45% in the -.2 m lyer nd 2% in the.2-.4 m lyer. In soil tillge with only furrower (P2), reductions were equl to 17 nd 12% in the lyers of -.2 nd.2-.4 m, respectively (Tle 4). Considering only soil tillge tretment, the use of hrrow + furrower cused sttisticl difference in PR. Soil tillge using hrrow + furrower ws more efficient in the reduction of PR, sttisticlly differing from the initil conditions nd from the tretment with furrower until the depth of 2 cm. Tle 4. Penetrtion resistnce (kp) efore (T1) nd fter (T2) soil compction, nd moilized re (m²) nd profile depth (m) fter soil moiliztion T1 T2 P1 P2.-.2 m A 2.28 B.2-.4 m A 2.56 A Moilized re -.8 A.9 A Profile depth -.31 A.31 A Sme uppercse letters in the row do not differ etween tretments y Tukey test t.5 proility level. Equl lowercse letters do not differ etween times y Tukey test t.5 proility level. P1 - Hrrowing + Furrowing; P2 - Furrowing In the lyer.2-.4 m, there ws no difference in PR etween tretments, proly due to the disc plow, which reches only the first 1 cm of the soil lyer. Likewise, moilized re nd profile depth did not differ sttisticlly (Tle 4). Vizzotto (214) oserved tht furrower shnk reduces soil compction long the crop row until the depth of 16 cm. Crvlho Filho et l. (28) oserved lrger moilized re of the soil lyer using moldord plow, followed y scrifier nd disc plow. Considering the interction Soil tillge x Sugrcne vriety, the efficiency in the reduction of PR followed the order P1V2 > P1V1 > P2V1 > P2V2, respectively with 54.5, 26.3, 23.5 nd 19.1% of PR reduction for ech tretment compred with the initil condition, until the depth of 25 cm (Figure 2). According to Portz et l. (29), the idel moisture for the mesurement of penetrtion resistnce is the moisture content t field A. PR (MP) B. Depth (cm) Depth (cm) P1V2 T Figure 2. Penetrtion resistnce grouped per tretment PR (MP) P1V1 T1 P2V1 T1 C D P2V2 T1 - Before tillge; P1 - Hrrow + furrower nd cultivted; P2 - Furrower; V1 - Soil cultivted with the vriety RB ; V2 - Soil cultivted with the vriety V2 RB T1 R. Brs. Eng. Agríc. Amientl, v.21, n.11, p , 217.

5 756 Uilk E. Tvres et l. cpcity, ecuse this condition provides good correltion with plnt root growth. The grvimetric moisture t field cpcity estimted in the studied Ultisol ws 9% for -.2 m nd 1% for.2-.4 m (Tle 1). Moisture contents t the moment of PR mesurement differed from the moisture t field cpcity in the studied Ultisol, nd high PR vlues were found t moisture contents lower thn 1%. Another fctor tht influenced the result of PR ws the moilized re; ccording to the profilometry, the moiliztion depth cused soil moiliztion until the mximum depth of cm. There ws no sttisticl difference etween the soil tillge systems for the vriles moilized re (.85 m²) nd furrow depth (.31 m) (Tle 4), proly due to the work of the disc plow, which moilized the soil until the depth of 1 cm, which suggests studies using other implements in the evluted Ultisol. In studies with other types of soil, such s criferric Red Ltosol, lrger re ws moilized using moldord plow, followed y scrifier nd disc plow (Crvlho Filho et l., 28). In ddition, the use of the sme implement pplied t different depths or under different covers (Deisi et l., 21), or the use of different implements, ut whose ction is of lower impct on the soil, such s hrrow nd furrower, my not cuse significnt differences in the soil. Significnt correltion ws found etween furrow depth nd fine snd content (R² = -6%), which suggests decrese of moiliztion in susurfce with the increment in fine snd content. Other correltions with furrow depth were oserved with w (R² = 45%), corse snd (R² = 42%) nd OC (R² = 33%); nd the est correltions with MA were oserved with w (R² = 46%), CO (R² = 32%) nd fine snd (R²= -31%), suggesting tht orgnic cron nd soil moisture during tillge positively contriuted to greter soil moiliztion, while cly nd fine snd contriuted negtively, possily ecuse their contents re lower thn those of corse snd, fvoring the reduction of wter vilility in the profile. Conclusions 1. Tillge system reduced soil penetrtion resistnce in the -.2 m lyer. 2. Corse soil frction, moisture nd orgnic cron positively contriuted to greter moilized re nd profile depth. 3. Soil tillge systems nd sugrcne vrieties llowed higher uniformity in the clsses of ggregtes. 4. Penetrtion resistnce chrcterized the soil tillge system etter, compred with soil ulk density. 5. The soil moiliztion promoted.31 m furrow depth. Literture Cited Bott, G. 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