Reproduced from Soil Science Society of America Journal. Published by Soil Science Society of America. All copyrights reserved. 7 .SgeR. aio,W 31 S enfed F ignforest. virgin VF, field; bean USA 53711 WI Madison, Rd., Segoe S. 677 © Conservation (2005). & 69:1448–1454 doi:10.2136/sssaj2004.0277 Management J. Water Am. & Soc. Soil Sci. Soil in Published ([email protected]). author *Corresponding 2004. Aug. Yguazu 19 Distrito ceived 45, CETAPAR-JICA, km Horita, 7, T. and Ruta Hoshiba, K. Manila, Bordon, Metro 7777, J. DAPO Philippines; Para- address: mailing CETAPAR-JICA, current of Kubota, experts A. former guay. Ogawa, K. and Kubota A. I soils. Rossa” not “Terra may coarse-textured Paraguay for root eastern suitable in vertical be practiced restrict the currently that could as the suggest system that results on no-tillage These level and seedlings. a germinating drying reached of soil development rain rapid after a with day of associated sixth subsoil with furthermore the compac- compared was Soil yr in MPa). tion (4.72 10 readings high in index extremely became horizon Cone soil Ap coarse-textured soils. their fine-textured of in cm) 11% 7 soils (about Coarse-textured compaction. 34% high lost low and texture, soil stability, texture. coarser aggregate soil with poor with associated were differed rates properties erosion soil long- High of physical Effects on included. no-tillage were over pits term thickness additional several horizon from Ap data in time, changes 2000, evaluate and To was investigated. 1990 con- were hydraulic pit in saturated location deep index, same ( cone 1-m ductivity density, exact A bulk the contents, soil. at clay and site coarse-textured each had at two prepared other different fine-textured “Terra a and had of fields Two in soil fields of 2000. and farmers’ no-tillage 1990 in properties Four studied long-term were texture texture. soil physical of different effect with on soils the objective Rossa” system The clarify world. farming to the in was soybean-based highest study the among this is of that level yield a at max e nalo ato hi ils(epc,19) Soy- 1998). (Derpsch, fields their of ( part bean–wheat sys- or soybean no-tillage all the of on using tem been 65% have about Paraguay in and growers rapidly, expanded tech- This nology Brazil. from system farming no-tillage a duced ai atradageaesaiiy(aabs and moisture, soil (Hajabbasi conserve 2000), stability Rhoton, or- aggregate 2000; soil maintain Hemmat, and to matter help They ganic properties. soil on pacts favorable. are conditions time when farmers the soybeans allowing seed shortening thereby to preparation, by land yields for soybean needed stabilized benefits it additional caused had as 1982 No-tillage in losses. rains topsoil severe heavy exceptionally soil minimize after and to erosion introduced soybean was both No-tillage for crops. wheat tillage system any the without use large-scale farmers continuously Most on Paraguay. pattern eastern in cropping farms predominant the now olSineSceyo America of Society Science Soil h nrdcino otlaefrigsaiie oba [ soybean stabilized farming no-tillage of introduction The h early the n otlaefrigssesuulyhv oiieim- positive have usually systems farming No-tillage hnei hsclPoete f“er os”Sisi aauyudrNo-tillage under Paraguay in Soils Rossa” “Terra of Properties Physical in Change rc,At Parana Alto trict, L)Mr. ilso TraRsa ol fesenParaguay eastern of soils Rossa” “Terra on yields Merr.] (L.) . K sat ,ageaesz itiuin n phrznthickness horizon Ap and distribution, aggregate-size ), rtcmaestivum Triticum 90,asyengoe nYguazu in grower soybean a 1980s, k uoa*JreBro,Kn ohb,TsiuiHrt,adKzoOgawa Kazuo and Horita, Toshiyuki Hoshiba, Kent Bordon, Jorge Kubota,* Aki ´ tt,Prga,scesul intro- successfully Paraguay, State, ABSTRACT ´ et.At Parana Alto Depto. , . obecopn is cropping double L.) Published onlineAugust4,2005 ´ aauy Re- Paraguay. , Glycine ´ Dis- K sat , 1448 n mrv olsrcueadwtriflrto rates infiltration water and 1998), structure soil (Benegas, improve temperatures and soil constant maintain aauy IA aa nentoa oprto gny F soy- SF, Agency: Cooperation International Japan JICA, Paraguay; Abbreviations: reduced ha were Mg 1.81 yields to soybean 1.08 (2000) by where al. Carolina et South Busscher by in profile. made soil were the observations in Similar compaction develop- soil root with poor by associated caused ment was drought yields reduc- of soybean the of that effect concluded tion the and growing fields studied farmers’ the in (2001) yields of on al. end et the at Seki periods period. dry short by affected 1989). al., et Vazquez (Betz 1998; (Be- resistance al., al., permeability penetration soil et et water high low al., Betz and 1994), 1998), et 1998; negas, al., Pierce (Benegas, et 2001; Pierce density al., 1998; et bulk (Seki high soil 1994), surface the nutri- in applied of ents sev- accumulation cause are These also problems. might indicated eral farming studies no-tillage some long-term hand, other that the On 1998). (Gill, rOio codn osi aooy orfres fields farmers’ Four Ultisol either is taxonomy. as Yguazu that soil in classified texture Rossa” to different is with “Terra according It called Oxisol 1). (Fig. soil or basalt clayey from red, derived a is Paraguay farm- no-tillage that confirm to desirable would be It de- furthermore yields. crop undesirable on effects prevent negative with to velopments would important changes be these consequently Monitoring systems. no-tillage sustainability of long-term affect may that factor important index. cone profile ta. 04 lveae l,20;Paoe l,2002). al., et regarding Prado available 2003; is al., information little et (Abreu very Oliviera Brazil However, 2004; in soils farming al., of no-tillage et properties of physical effects per- on the been system investigate have to studies long-term formed Several erosion. soil httpot fgriaigsyen antpenetrate. cannot hardness soybeans of germinating degree of a taproots reaches that monitored soil rain the investi- when after was determine hardness to soil soil in Rossa” changes mois- “Terra and soil gated fine-textured and a of hardness of soil ture thickness between textures. horizon relationship different of The Ap dependence in and soils Rossa” “Terra properties physical system farming on soybean-based a in no-tillage long-term textures. soil different with under vary properties established systems soil well no-tillage in not changes also long-term is any It whether Rossa” Paraguay. “Terra eastern predominate of soils the of properties physical prevent indeed can Paraguay, eastern in practiced as ing, h ihyedo h Yguazu the of yield high The h rdmnn oltp on ntesuyae feastern of area study the in found type soil predominant The an therefore are properties soil physical in Changes betvso hssuyaet lrf h fetof effect the clarify to are study this of Objectives AEIL N METHODS AND MATERIALS EAA,Cnr enlgc goeuroen Agropecuario Tecnologico Centro CETAPAR,

Ϫ 1 o vr P nraei mean in increase MPa every for ´ ititwr tde ndetail in studied were District ´ itithsltl been lately has District Reproduced from Soil Science Society of America Journal. Published by Soil Science Society of America. All copyrights reserved. ieadtocas-etrdsis o 00 iso 9fine 19 of pits 2000, For soils. coarse-textured two include two pits and additional these fine 1990, For included. were pits iei oeta orfed,dt rmsvrladditional several from data fields, four than was more horizons over in thickness Ap horizon time Ap of in thickness changes evaluate the To determined. and were Profiles horizons, detail. in into studies divided fields four the for cm location 20 same and soybeans by for sown cm were 35 Seeds wheat. of wheat. for distances was row at crop with for winter drilling The system yr. farming that 10 farmers no-tillage least by soybean-based managed native was a were between soil fields employed comparisons (VF) All obtain soils. forest to cultivated virgin and study the a in 2000, push- included by In 4 rows hyperthermic and across and regime. regime randomly water SF3 times temperature udic The four and an system. measured by was classification Kandiudox, characterized index soil is U.S. Rhodic soil the as by Paleudult classified Rhodic are as coarse 2 a field and Soybean had intermediate. 1 (SF4) was investigate (SF3) (SF2) 4 3 to 2 field field Soybean and soybean 2000 texture. (SF1) whereas 1 and textured field fine 1990 Soybean are properties. between soil period in changes 10-yr a over Yguazu in sites surveyed of Location 1. Fig. DiiRk oy o,Ld,Jpn.Aps-oesi hard- 12 soil a push-cone with A (Daiki) Japan). meter Ltd., ness Co., Kogyo Rika (Daiki im aewsue odtrietecn ne.Tecn tdpho ,1,ad2 cm. 25 and 15, 5, of depth at cone The index. cone the determine to used was base diam. y5k rdsprmoe nteYguazu the of on lines superimposed intersecting grid those km on of 5 based by was Selection 5 2000 added. a in were sites 27 soils additional coarse-textured 8 and ytosmln ue e oio ihavlm f10cm 100 of volume a with taken horizon were per analysis tubes physical for sampling samples two Soil by bag. plastic mixed a and of horizon Soil in per analyses spots (1998). three distribution, from For collected al. aggregate-size were samples harvest. wet et and soybean Miura distribution after by particle-size 1995 taken in were collected samples data compared the were fields with soybean of thickness investigated horizon continuously Ap were four The 1984). 2000 Gomez, replica- and and unequal for (Gomez 1990 calculated tions as in test LSD thickness the horizon using compared Ap of values mean oba ilsudrn-ilg amn eeslce.The selected. were farming no-tillage under fields soybean n19 n 001mde iswr rprda h exact the at prepared were pits deep 1-m 2000 and 1990 In ,2 ,ad4ae1truh4i h a,respectively. map, the in 4 through 1 are 4 and 3, 2, 1, Њ 40 UOAE L:PYIA RPRISO TRARSA SOILS ROSSA” “TERRA OF PROPERTIES PHYSICAL AL.: ET KUBOTA Ј iclrcn n . cm- 1.8 a and cone circular ´ ititaddsrbto f“er os”si nesenPrga.Lctoso oba il (SF) field soybean of Locations Paraguay. eastern in soil Rossa” “Terra of distribution and district ´ itit Only District. 3 .–.5 .501 and 0.25–0.1, 0.5–0.25, ehd(lt n ike,18)i 00 Wet-aggregate 2000. in 1986) Dirksen, and (Klute method nlzr(oe,13)ta hks3 ie e iue The ( aggregate minute. fraction per size type each times wet of Yoder 30 percentage the shakes weight a that by using 1936) determined (Yoder, 1972) analyzer was (Sato, soil method surface sieving falling-head the the of by distribution meter and 1990, three-phase by in soil measured method was by constant-head conductivity the measured hydraulic samples Saturated (Daiki). core phase solid the of mass in oven-dry from dispersion. estimated physical was for density ultrasonic Bulk used (Three-wave was mixer Shimazu) ultrasonic SUS-103, An cleaner, (Claes- 1997). solution hydroxide al., sodium et after a sen by solution oxide bicarbonate iron samples of phosphate-sodium of removal sodium dispersion pipette chemical a for Kohn-type was used a agent using The 1986), analyzer. Bauder, and (Gee method and presented. horizon, each was at value horizontally mean meter the hardness soil the ing ntle tti et.Tecn ne a esrd6times 6 measured was index be cone not The could depth. type this this at of installed tensiometers because measured not a nlssw rue grgtsit ar-admicro- contrasts General and point. cutoff macro- the into as mm aggregates 0.5 using grouped aggregates we analysis cal eecmue vryasfrfn-etrd(SF1 fine-textured for years over computed were etd h arcwtrptnila h -mdphwas depth 5-cm pre- the were at values mean potential and water cm), matric 25 (Daiki) The tube and mercury (15 sented. a depth using each measured tensiometers, for was water potential soil matric six The by SF2. and was SF1 CETAPAR JICA type to soil identical of at The Agency). Paraguay), Cooperation field International en (Japan experimental Agropecuario an Tecnologico (Centro in mm) (108 determined rainfall after index were cone in change the and potential, oretxue (SF3 coarse-textured olpril-iedsrbto a nlzdb h pipette the by analyzed was distribution particle-size Soil h eainhpbtencn ne n olmti water matric soil and index cone between relationship The ϩ Ͻ )soils. 4) . m a eemnd o statisti- For determined. was mm) 0.1 Ͼ .,2010 1.0–0.5, 2.0–1.0, 2.0, ϩ )and 2) 1449 Reproduced from Soil Science Society of America Journal. Published by Soil Science Society of America. All copyrights reserved. oba il 25 S 4 field Soybean oba il 25 S 3 field Soybean oba il 25 S 2 field Soybean r rwtsaos hr eid fdogtlasting drought of periods Short seasons. wet pronounced or without mm dry 1803 was rainfall annual Mean oba il 25 S 1 field Soybean w rusaerfre oa ietxue “Terra fine-textured as respectively. to Rossa,” “Terra referred coarse-textured and are Rossa” groups two ly(F n F)(i.3.Truhu hssuythese study this with Throughout 3). fields (Fig. SF4) coarse-textured and (SF3 and clay SF2) and (SF1 ewe ietxue ilswt oeta 0 clay differentiate 40% to than clay used more The with was 1. fields layer Table fine-textured in surface between given the are in study content this soybean in four used the of fields history cropping and Location year. a ihri F n F oprdwt F which VF, with compared SF2 and index SF1 cone in cm in 30 higher and 10 observed was between density were bulk The density. SF1/2 bulk and in- and Differences content m. VF 1 clay of at between Their 80% type reached area. and dominant depth the with the creased in soils represent Rossa” fields “Terra These 3). (Fig. ieLcto ao eeainC†N‡US olclassification soil U.S. NT‡ CT† vegetation Major Location introduced. was cropping. no-tillage no-tillage before annual cropping NT, tillage 25 ‡ conventional S annual CT, † forest Virgin Site sites. studied of Description 1. Table the of time any at occur however, may, weeks several CETA- of temperature air and precipitation average Monthly 2. Fig. 1450 iia atrso lycnettruhu olprofiles soil throughout content clay of patterns similar nFg n i.2 vrg aiu temperatures maximum exceed April) Average to 30 (November 2. season Fig. soybean the and during 1 Fig. in Parana Alto District, enana rcptto a 83mm. 1803 was precipitation annual Mean Yguazu station, experimental PAR codn otesre n20,V,S1 n F had SF2 and SF1, VF, 2000, in survey the to According Њ Yguazu the of data climatic and location Geographic hl iiu eprtrsrmi rud20 around remain temperatures minimum while C ifrnei Compactness in Difference ´ tt,esenPrga r shown are Paraguay eastern State, RESULTS ؇ ؇ ؇ ؇ ؇ 32 24 25 23 28 ؅ ؅ ؅ ؅ ؅ 08.0 48.0 12.4 40.2 31.3 ´ ″ ″ ″ ″ ″ itit aauy(1990–2000). Paraguay District, 055 W 055 W 055 W 054 W 055 W OLSI O.A.J,VL 9 ETME–COE 2005 SEPTEMBER–OCTOBER 69, VOL. J., AM. SOC. SCI. SOIL ؇ ؇ ؇ ؇ ؇ 00 12 03 59 00 ؅ ؅ ؅ ؅ ؅ 50.8 46.9 16.8 15.9 27.7 ″ ″ ″ ″ ″ Ͻ 40% Њ oba-ha 5Roi Paleudult Rhodic 15 3 soybean-wheat oba-ha 0Roi Paleudult Rhodic 10 6 soybean-wheat oba-ha 3Roi Kandiudox Rhodic 13 2 soybean-wheat oba-ha 51 hdcKandiudox Rhodic 18 25 soybean-wheat utoia re hdcKandiudox Rhodic – – trees subtropical C. ´ vryears. over eelwweebl este n oeidcswere indices cone (0.7 and value densities lowest The bulk high. where low were osataogtesi rfl,adS1adS2had SF2 and SF1 and profile, soil higher the along constant hne fteevle eas ifrn measuring different the 1990, because In employed. values compare were methods directly these cannot of no-tillage we of changes although yr 3), 10 (Fig. after farming profiles in tendencies different ubdsi nV Ryod ta. 2000). al., et (Reynolds VF cm in undis- soil 40 the in turbed below measurements affected channels, depth possibly root cracks wormholes, at and as such values factors Other bulk index 3). (Fig. high cone despite and profile, density the remained along and constant fields relatively soybean with compared higher was bandi h td fBngs(98.The (1998). Benegas of study the in obtained dt o hw) hsvlewsmc ihrthan higher much was systems no-tillage 2000 value of studies in other This in reported measured previously shown). were not indices cone content (data water when the higher although occurred was This 2000. in MPa to 15- the index at cone density m and Mg bulk density 1.56 bulk were in highest In increase The observed depths. 3). an change 30-cm (Fig. was main texture 2000 the SF2, soil in and with SF1 differed fine-textured index cone and soils of contents. of compactness clay rates for cause high uptake usual with water a 0.31, is high This dryness were by as presented). trees SF2 caused not been and (data have SF1, respectively could VF, 0.52, of water and volumetric depth 0.41, The this cm. at 20 content below showed increase VF marked whereas remained profile a hand, the throughout other SF1/2 the in below on low just indices, layer Cone compacted surface. a the of presence the indicated xrml ihcn ne Fg ) nascainof association An 3). (Fig. index cone high extremely Meredith 1989). al., et Vazquez 2000; al., et (Busscher low soil the loosen the to enough compacted, great are not are silt hydration dehydration accompany and and that sand forces shrinking fine in and low in swelling soils high when and that observed clay also (1961) Patrick and tte3-mdphi F,wihcicddwt an with coincided which SF4, in depth 30-cm the at inw eetdabgices ncn ne nSF4 in and from 20 index increased Between index cone 20%. cone about the in cm, of 40 contents increase clay big low addi- a a with in detected But observed SF4). we and was tion (SF3 density soils bulk coarser-textured in with increase similar A tively. ifrnei auae yrui Conductivity Hydraulic Saturated in Difference h auae yrui odciiy( conductivity hydraulic saturated The fet f1 ro otlaefrigo ukdensity bulk on farming no-tillage of yr 10 of Effects K sat K ihhg ukdniyudrn-ilg a also was no-tillage under density bulk high with sat austa F n F.I 2000, In SF4. and SF3 than values aaeet(yr) management uaino land of Duration Ϫ 3 n .8Mai F n20,respec- 2000, in SF1 in MPa 0.98 and ϫ 10 Ϫ 5 ms cm Ͻ K Ϫ n19 o4.72 to 1990 in 1 sat 1 a obtained was ) a relatively was K sat K K showed ) sat sat values fVF of Reproduced from Soil Science Society of America Journal. Published by Soil Science Society of America. All copyrights reserved. i.3 lycnet ukdniy oeidx n auae yrui o ffn-etrdadcas-etrd“er os”sis Gen- soils. Rossa” “Terra coarse-textured and fine-textured of zon hydraulic saturated and index, cone density, bulk content, Clay 3. Fig. macro- of proportion high ( extremely aggregates an had SF2) and aino lymnrl n l n e xds(i tal., et (Six oxides Fe- and Al- and minerals cemen- by clay and of soil the tation of size particle homogeneous caused the probably by was difference This SF4). and (SF3 soils ( aggregates (SF1 soils fine-textured 1990, In 4. Fig. in shown are zon edmto n20 V:vri oet F oba il) at field). soybean SF: forest, virgin (VF: falling- 2000 by in and 1990, method in head method constant-head the by measured was odciiy( conductivity ifrne nageaesz itiuino phori- Ap of distribution aggregate-size in Differences fca otn saalbefrS1adS2i 90 The 1990. in SF2 and SF1 for available is content clay of Ͻ Ͼ grgt-ieDistribution Aggregate-Size K . m eedmnn rcin ncoarse micro- in while fractions dominant layer, were mm) surface 0.5 the in mm) 0.5 sat ftesismaue n19 n 00 odata No 2000. and 1990 in measured soils the of ) UOAE L:PYIA RPRISO TRARSA SOILS ROSSA” “TERRA OF PROPERTIES PHYSICAL AL.: ET KUBOTA K sat au ruswti er n rusoe er.Cagsoe years over Changes years. over groups and years within groups value oe ils amr aeosre ollse from rains. losses heavy ex- soil after and observed particularly large fields have in their wind Farmers strong fields. and posed rain erosion soil heavy to by due caused probably were thickness horizon Ap aantson.Teerslsidct that indicate results These shown). not data phrzndphwsosre,wieS3adSF4 and SF3 while In observed, period. was (clay 10-yr depth horizon the Ap contents over (clay SF2 changed SF1and but completely soils fine-textured had that than horizons soils Ap coarse-textured deeper 1990, slightly In fields 5). soybean (Fig. four all investigated in thickness horizon Ap in decline 1). (Table yr 20 both than although more shown), for not identical farmed (data was been 2000 1990 had in in fields VF SF2 of and that SF1 to aggregate- the of that distribution noted “Terra be size also fine-textured should well- It of of soils. reduction Rossa” stability a prevent aggregate to Rhoton, able developed be 2000; not Hemmat, may it and 2000), (Hajabbasi aggre- stability maintain to gate thought is system farming no-tillage the signifi in was reduction mm the 2.0 than macroaggregates, bigger but of soils aggregates class fine in observed the we macroaggregates within period for 10-yr reduction the slight Over a SF2. and SF1 in 2000) i.4 itiuino grgtsbge hn05m nteA hori- Ap the in mm 0.5 than bigger aggregates of Distribution 4. Fig. fln nS3 sn ukdniyo .2ad11 Mg 1.13 and 1.42 of hectare density bulk per a lost m using was SF3, topsoil in but land of of Mg period We 2280 10-yr shown). for that not the estimated account (data unaltered over to essentially were basis density results weight bulk per in a differences Ap on calculated changes also We horizon 11%). for of not (loss but soils soils fine-textured Rossa” signifi- “Terra statistically in coarse-textured was reduction for yr 34% cant 10 The over thickness 6). horizon (Fig. Ap analysis the were sites in additional included when obtained was result similar A Ϫ eentsgiiat *idctssgiiac ewe olgroups soil between significance indicates ** significant. not were rlcnrs eeue odtriedfeecsbtensoil between differences determine to used were contrast eral a revealed 2000 and 1995, 1990, of survey soil The 3 P smaue n19 n 00 hs hne in changes These 2000. and 1990 in measured as hnei hcns fteA Horizon Ap the of Thickness in Change Ͻ ϭ 0)hdls bu 0 fterA horizon. Ap their of 50% about lost had 40%) .1 ro as D( SD bars: Error 0.01. n Ͼ ϭ 0)a2%rdcinin reduction 20% a 40%) 2). at( cant vnthough even Ϫ 18%, 1451 Reproduced from Soil Science Society of America Journal. Published by Soil Science Society of America. All copyrights reserved. et nrae xoetal hnLog when exponentially increased depth h nraei oeidxa h 5c et talower a m dried at Mg depth (1.42 25-cm soil density the bulk MPa. at the 7 index cone as As in high increase as 2001). The values reached al., index cone et the further, (Sato growth taproot u . P a ece tLog at reached was MPa 1.3 but bu . P)si adessat etitn soybean of restricting index starts (cone hardness soil point MPa) this 1.3 At about 2.0. above rose potential] i.6 hnei phrzntikeso w etr rusof groups texture two of thickness horizon Ap in Change 6. Fig. from yr, 5 in fields soybean of thickness horizon Ap in Change 5. Fig. 1452 fbl est n olmitr odto.A bulk m a At Mg condition. 1.62 moisture of soil density and density bulk of a oepoone fet nsi adesa soil as hardness soil on drier. density effects becomes bulk pronounced that indicates more data has This 2.25. about of tial] fet fBl est n olWtrPotential Water Soil and Density Bulk of Effects rbblt.Nme fsmlswr ,2,4 n 0fo h left the from 10 5% and bars. at 4, right LSD 21, indicate the 4, bars were to vertical samples The of yr. Number 10 probability. in soil Rossa” “Terra (1998). al. thickness et horizon Miura Ap by The measured system. was 1995 no-tillage of under 2000, to 1990 iue7cerysosta olhrns safunction a is hardness soil that shows clearly 7 Figure nSi Hardness Soil on Ϫ 3 Ϫ h oeidxa h 15-cm the at index cone the , 3 a o ssepa t1 cm, 15 at as steep as not was ) 10 [ OLSI O.A.J,VL 9 ETME–COE 2005 SEPTEMBER–OCTOBER 69, VOL. J., AM. SOC. SCI. SOIL Ϫ arcwtrpoten- water matric 10 [ Ϫ arcwater matric rprywsascae ihussanbyhg rates high unsustainably with associated was property oio hne nA oio hcns t5 o10-yr to to 5- intend at accumulate thickness therefore losses horizon We Ap soil time. in as changes of concern monitor periods of longer cause over a be may intervals. oio n1 r i.6.Ti oprswt 11% with compares This 6). Fig. Ap the yr, of cm 10 ( 7 or in (34% erosion horizon to due losses topsoil of fmcogrgts( macroaggregates of h lycneti h osi n eetdmarked detected and on topsoil based the soils in Rossa content Terra between clay textured distinguished the coarse We and 1998). 2000; fine Gill, Hemmat, 2000; and (Hajabbasi Rhoton, sustainable consid- more generally are ered that systems prac- no-tillage in agronomic even current tices evaluating of in sustainability proper- considered long-term be soil the to to needs regard variation This with ties. substantially vary Rossa” can “Terra as soils, to referred commonly Paraguay, eastern cm onl 5 crop after of levels penetrate 25-cm exceeded depth can that a and hardness roots at 15- soil loss high the moisture in resulted at soil rapid constant The stayed while depth. day, index ninth the cone the on started MPa the After depth 7.8 5-cm reached depth. the and shallower at increase to at readings at index indices than cone Cone day, 8). lower fifth (Fig. were cm cm 25 and 25 mm) 5 (108 rain between after depth d 5 at for constant remained field mental osntpoueeog ims o ai ground rapid maintain to for harvest after biomass biomass little wheat enough leaves winter, and cover in produce periods not dry and does erosion cool the to for Due responsible problem. largely been have may itself the between distribution aggregate-size in differences o rprino arageae 3% n this and (30%) macroaggregates of proportion by characterized low were a soils Coarse-textured types. two tv feto obas oee,tewne rpwheat crop winter the however, soybeans; im- of neg- effect that the ative for crop compensate Laflen winter could 1985; stability a aggregate al., rates proves Using et exceed 1979). (Alberts corn Moldenhauer, to as and found such crops were other erosion fields of consequence, soybean a from As nitro- rates of residues. rate soybean decomposition al., rapid gen-rich et the (Fahad of stability a because aggregate have 1982) soil can on Soybeans effect system. negative farming con- with tillage tilled greater been ventional a have would of stability change aggregate the absence that in possibility the in exclude cannot However, we control Paraguay. practiced eastern predominantly scale in large double in soybean–wheat a the system to cropping such the due of likely That conditions is study under 2000). present detected not Rhoton, was 2000; effect positive Hemmat, (Hajab- also structure and aggregate re- could basi for not beneficial trend as if generally of This are soils thought systems No-tillage 2000. halted. fine-textured least at in in or versed 71% rates erosion to increase 1990 in from soils 85% fine-textured in macroaggregates for decline a Ͻ aapeetdhr hw httetpclsisof soils typical the that shows here presented Data experi- CETAPAR the in measured hardness soil The u uvyoe 0y eidfrhroeshowed furthermore period 10-yr a over survey Our m o ietxue ol ihahge proportion higher a with soils fine-textured for cm) 3 olHrns fe Rain after Hardness Soil DISCUSSION Ͼ 0) vnteelwrrates lower these Even 70%). olwn rain. following d 6 y Reproduced from Soil Science Society of America Journal. Published by Soil Science Society of America. All copyrights reserved. htti hlo otsse aepat susceptible short. were plants periods drought made when even system stress drought root to shallow roots this tap- lateral concluded that authors soybean The whereas surface. of the vertically near 50% vigorously elongate grow than not more did of that even roots finding (2001) to the layer, al. explain and et topsoil can ha Seki 5-cm This 200 farming. the as no-tillage past large with elongate as roots areas enough seventh not in have usually the sowing are on days complete six strength exceeded or to Five soil was study. a value our in with this day soil and this penetrate MPa, above not cot- 2.9 index that could d observed roots cone 6 (1969) ton of Ratliff the period and dry increase Taylor of short threshold. to A hardness 2001). sufficient soil al., a was et at (Sato decrease MPa to 1.27 reported taproot was Soybean with data growth potential. hardness our water increasing matric and of soil soil decreasing association fine a clear of a in layer showed MPa content also surface of however, the 4.72 exposure clay were, 1984; in of values increase detected index lowest al., index furthermore cone High cone the would et subsoil. high Plowing the with (Doran tion. extremely temperatures soil an soil showed The high hardness. and soil ratio. ture C-N of wider addition a and through with increas- surface, et as matter structure (Pierce soil such organic problems tillage aggregate the other periodic cause cover produce stabilize may by plowing that rapidly that ture, corrected crops to be manure were biomass problems can green enough results management density, some soil promising with that Recently, obtained suggested crops. alter- been on that winter has focus problem native therefore second It a should climatic soybean- is pattern the stress cropping improve unfavorable drought based to incurring Attempts to of winter. risk in due been conditions not ero- has successful hand, control other to economically the way on a cultivation Wheat as yield. there- sion. feasible is high economically soybeans their not of fore of frequency the cropping because highlight the however, Paraguay Reducing do, cash regards eastern results major with the Our in generalization are solutions. make crop Soybeans tential to problem. this difficult overcome is 2). to it (Fig. study October to April win- from during more months occurs precipitation since ter annual particularly the field). of occurring high, experimental 50% runoff (CETAPAR therefore than cm surface is 25 of wheat and risk 15 under The at layer. measured protective index cone a and potential water matric between Relationship 7. Fig. eodpolmdtce nti td sta fepoutv ntrso rso oto MGeo and (McGregor control erosion of terms in erproductive of that is study this in detected problem second A and texture soil to relate they as particularly erosion, of necessary be may pattern cropping the in change A u otelmtdsml ieue nti initial this in used size sample limited the to Due UOAE L:PYIA RPRISO TRARSA SOILS ROSSA” “TERRA OF PROPERTIES PHYSICAL AL.: ET KUBOTA h olsraet anadwn,wihwudb count- be would which wind, and rain to surface soil the germina- affect negatively can that 1986) al., et Wilhelm mois- soil of loss rapid more control, weed difficult ingly struc- soil for benefits potential some Despite 1994). al., bulk high and hardness soil as such systems, no-tillage of potential. yield high a maintain to addressed associated be to the needs and hardness Soil dangers structure. the on aggregate studies detailed more conduct po- their to and need here described problems of extent the to i.8 hnei oeidxa ifrn etsatrri 18mm) (108 rain after depths different at index cone in Change 8. Fig. P a on orsrc oba aro rwh(aoe l,2001). al., et (Sato at MPa growth 1.27 taproot than soybean *greater restrict to SD found bars: was Error field). experimental (CETAPAR ( 1999 Dec. 14 on n ϭ ϭ 0.01. ) h otdln niae oeidxo .7Ma which MPa, 1.27 of index cone a indicates line dotted The 5). P ϭ .5 *rae hn12 P at MPa 1.27 than **greater 0.05. 1453 Reproduced from Soil Science Society of America Journal. Published by Soil Science Society of America. All copyrights reserved. be,SL,JM ecet n ..Riet 04 Escarificac 2004. Reinert. D.J. and Reichert, J.M. S.L., Abreu, International Japan the an by CETAPAR, Tokyo. (JICA), in run Agency out is Cooperation carried that was institute study fields agricultural This their study. offered We who this farmers appreciated. of for Aureliana greatly support Mrs. the is for by Bogado grateful con- are Santiago provided measurements Mr. assistance and laboratory The Franco and 2000. in surveys ducted soil in support sustainable. magnitude not the are of study losses this soil in as and observed production alike crop into for conservation issue soil variability urgent an soil is This take account. controlled that under them conditions evaluate experimental to crops on experiments manure scientific providing green by augmented also how- be observations, to while need practical soil ever, These the cover. in ground biopores good form and ers oats sativus that ( nus radish manure farmers green whereas system, by root oped observed soil been eastern ( of has In reduction it 1981). on Derpsch, Paraguay effects and (Kemper positive compactness with mass root wheat indi- higher substantially results than crops produce and some winter Brazil that in Several cated evaluated site. been already specific a have the at alleviating of encountered capable problems are that crops winter east- in Paraguay. farming ern no-tillage solving with in associated methods problems mechanical the or physical prefer to therefore We biological 2004). al., et Wilson 1992; Mutchler, 1454 epc,R 98 itrclrve fn-ilg utvto fcrops. of cultivation no-tillage of review Historical 1998. 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